CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

+28 VDC

P/O

R31

# 1 AUDIO TONE

R32

(TO HEADSETS)

(SHEET 1) X

(NOTE 5)

# 1 TONE

R27

R28

R30

LEVEL

R24

R25

R26

Q14

Q15

TONE

# 1 AUDIO

INTERRUPTER

AMPLIFIER

R28

R34

# 2 AUDIO TONE

CR7

R35

P/O

Q13

(NOT USED)

Q12

# 2 TONE

GEN

P/O

TONE

(NOTE 5)

SWITCH

TONE

LEVEL

OSCILLATOR

OFF

CR6

AMPLIFIER

Q16

# 2 AUDIO

(NOTE 4)

AMPLIFIER

AUDIO TONE CIRCUITS

NOTES: (CONT)

REMOVAL OF GROUNDS IN FROM GENERATOR SWITCH DISABLES

ABBREVIATIONS:

AUDIO TONE CIRCUITS.

AMP − AMPLIFIER

AUDIO TONE OF 680−1700 HZ INTERRUPTED AT A RATE OF 150 HZ.

ENG − ENGINE

MAXIMUM OF 3.0−3.5 VOLTS WITH OUTPUT TERMINATED INTO

GEN − GENERATOR

100 OHM LOAD. (VOLTAGE MEASURED WITH RMS AC VOLTMETER.)

OSC − OSCILLATOR

REFER TO ELECTRICAL SYSTEM WIRING DIAGRAM (APPLICABLE PART

P/O − PART OFF

OF HMI) FOR INTERCONNECTION WIRING INFORMATION.

PRESS − PRESSURE

RMS − ROOT MEAN SQUARE

TEMP − TEMPERATURE

XMSN − TRANSMISSION

30−195−2

Figure 17-19, Autronics 2146-5 Warning Audio and Lights Flashing Control

Circuit (Sheet 2 of 2)

When activated, either N₁ or N_R sensing

EPO warning control unit; except as follows:

circuits activate and control the engine out

The unit contains additional circuits for

flashing light, audible warning tones and the

sensing low main rotor (N_R) speed to control

audible warning horn.

engine out flashing light and audible warning

horn indications, and generation of an

Audible warning tones No. 1 & 3 are activated

additional separate audible warning tone No.3

and controlled by either N₁ or N_R sensing.

when low N_R speed is sensed. (For a simplified

internal block diagram of the unit, see

The Autronics 2200−3 is a sealed unit without

Figure 17−5.)

adjustments; an internal defect requires

The unit senses low N_R speed at approximate−

replacement of the unit.

ly 98% N_R rpm (equivalent to tachometer

NOTE: Input, control and output circuits, sig−

generator output ac voltage with a frequency

nals and voltages differ from those of the

of 68.6 ±0.7 Hz), or less. Low N_R speed sensing

2146− 5 unit as described above. Internal

functions incorporate disable and time delay

schematic diagrams of the unit are not pro−

circuits.

vided; internal maintenance is not practical.

A. Autronics 2200-3 EPO Warning Control

Unit Maintenance

23. Autronics 2200-3 EPO Warning Control

Unit

An internal malfunction requires removal and

replacement of the unit. Remove and replace

The autronics 2200−3 EPO warning control

the unit as described for the Autronics 2146−5,

unit is a sealed, solid state device that

except disregard information on adjustment of

functions similarly to the Autronics 2146−5

internal controls. (autronics 2200−3 unit does

Page 17-61

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

not have accessible internal adjustments.) For

B. Negative (Ground) Input Fault Dimming

information on checking operation of the unit,

Circuits

refer to the following data.

(Ref. Figure 17−21) Negative input fault

dimming circuits function when a ground is

(1). For information on troubleshooting the

applied from external sensing switches to the

unit installed in the helicopter, refer to

dimmer unit.

Table 17−2 and Table 17−3.

When the ground fault is applied, a current

(2). For additional maintenance informa−

path is completed from the external ground

tion on the unit, refer to Table 17−4.

through the associated external caution lamps,

diode CR9, and normally closed contacts of

dimming relay K1 to +28 Vdc for bright lamp

24. Grimes 70-0054-1 Indicator Lights

indication.

Dimmer Assembly (Panel Type A)

For a dim lamp indication, the dim−bright

switch completes a current path from ground

The Grimes 70−0054−1 indicator lights

through the winding of dimming relay K1 and

dimmer assembly is a solid state device that is

diode CR1 to +28 Vdc. This selects a current

used with the EPO warning unit for caution

path or the fault indicator lamps through

and warning lights dimming and dims

zener diode VR1 to +28 Vdc.

instrument panel lights when the option night

lighting system is installed.

When selected, zener diode VR1 introduces a

constant voltage drop to reduce lamp voltage

The indicator lights dimmer assembly is

for simultaneous dim lighting of all caution

installed at the lower left interior of the

light indicators that are illuminated.

instrument panel console.

The dim−bright circuit is common to and

functions identically for all negative input

A removable cover permits access to two

fault dimming circuits. is common to and

circuit boards and components of the indicator

functions identically for all negative input

lights dimmer assembly for maintenance and

fault dimming circuits.

repair.

C. Positive (+28 Vdc) Input Fault and

The indicator lights dimmer assembly contains

Function Dimming Circuits

the following internal circuits.

(Ref. Figure 17−21) Each of the two positive

(+28 Vdc) input fault dimming circuits, and

A. Indicator Lights Dimming Assembly

the one +28 Vdc input function dimming

Circuits

circuit, control illumination of separate

external warning light indicators on the

The indicator lights dimming assembly

instrument panel.

contains components for use in for use in four

When a +28 Vdc input is applied to diode

negative input signal fault dimming indicator

CR15, a current path is completed from

circuits for the four caution light indicators,

ground, through transistor Q3, the external

three positive input fault and function

START PUMP lamp and diode CR15 to the

indicator circuits for three warning light

+28 Vdc applied for a bright lamp indication.

indicators and a panel light dimming circuit (d

below) for panel lamps. In addition, test

The + 28 Vdc applied through dimming relay

circuits are included for all the circuits.

K1 contacts to resistor R4 at the base of

transistor Q3 forward biases Q3, so that the

Figure 17−20 is a schematic diagram of the

lamp current path is through Q3, bypassing

dimming assembly.

parallel resistor R3. For a dim lamp indication,

the dim−bright switch energizes K1 removing

Figure 17−21 is a partial breakdown of the

the positive voltage applied to the base of Q3;

indicator lights dimming assembly overall

Q3 ceases conduction and lamp current must

schematic diagram with associated circuits

flow through resistor R3. The resulting voltage

and shows typical circuits separately by

drop across R3 reduces lamp voltage and dims

functions.

the lamp.

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

The circuit for the XMSN OIL TEMP &

(4). Connect electrical plug to dimmer

PRESS lamps functions identically, except a

assembly. Turn on power, push−to−test

pulsating positive dc voltage input is provided

switch for the indicator lights and check

by the transmission oil and temperature light

for proper functioning of the lights.

flasher circuit of the EPO warning unit, to

flash the associated lamps.

(5). Reinstall instrument panel fairing.

The circuit for the ENG OUT warning light

25. Autronics 2245-1 Indicator Lights Dimmer

functions in the same manner as the XMSN

Assembly (Panel Type B)

OIL TEMP & PRESS dimming circuits, except

resistor R1 is directly switched in the lamp

The Autronics 2245−1 dimmer assembly is a

current path for lamp dimming by dimming

solid state device associated with the caution

relay K1.

and warning indicator lights of the type used

in instrument panel type B. The unit contains

D. Panel Lights Dimming Circuit

28 Vdc and ground test circuits, with isolation

(Ref. Figure 17−21) When the night lighting

diodes, which are part of the PRESS−TO−

system is installed, a variable positive voltage

TEST circuit for the lights. The unit also

from the panel and instruments light dimming

contains a switching regulator to regulate

potentiometer R113 is applied to the base of

voltage for instrument panel and instrument

transistor Q1. The variable voltage varies

light dimming. Caution and warning indicator

external panel lamps current flowing through

lights may be dimmed by pressing the face of

transistor Q2 to control panel and instrument

each indicator. See Figure 17−22 for a sche−

lamp illumination.

matic diagram of the dimmer assembly. The

unit contains components used in the following

E. Grimes 70-0054-1 Indicator Lights

circuits.

Dimmer Assembly Repair

A. Dimmer Assembly Associated Circuits

Replace circuit component as necessary in the

indicator lights dimmer assembly. Refer to the

The unit contains 16 diodes and other circuit

functional information and troubleshooting

components used in: six negative fault input

data for the indicator lights dimmer assembly

indicator circuits for six caution light indica−

to locate and isolate defective internal compo−

tors; two negative fault input signal indicator

nents.

circuits for main transmission (XMSN) oil

F. Grimes 70-0054-1 Indicator Lights

temperature (TEMP) and pressure (PRESS)

Dimmer Assembly Replacement

warning light indicator; a positive input signal

indicator for the START PUMP light indicator;

(Ref. Figure 17−3)

a circuit for an engine (ENG) OUT warning

light indicator; and a panel and instrument

(1). Check that all electrical power is OFF

lights dimming circuit.

and remove left instrument panel

fairing.

In addition, internal components permit

simultaneous press−to−test checking of all the

(2). Disconnect the electrical plug from the

circuits and light indicators.

dimmer assembly, remove the mounting

screws and washers, and lift out the

Figure 17−22 is a partial breakdown of the

dimmer assembly.

dimmer assembly overall schematic diagram

(3). Position replacement dimmer assembly

with associated light circuits and shows typical

and install attaching hardware.

circuits separately by functions.

Page 17-63

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 17-4. Input/Output Signals - Autronics 2200-3 EPO Unit

Input

Output

Connector

Name

Signal or Control

Name

Signal

J21 Pin

J22 Pin

N₁ tach gen

Ac voltage, 36.75

Eng out light flasher

Pulsating 28 Vdc with

±1.75 Hz, or less

and audible warning

3-5 Hz flash rate, 0.2A

horn

max., 28 Vdc present

for min. 25% - max.

75% of flash rate

period.

Xmsn oil & temp

Same as for J21, Pin F

flasher

Audio warning tone

Interrupted 680 to 1700

No. 1

Hz, 0.9 ±1 Vac into 16K

ohm load; interrupted

120 ±40 times/minute,

ac voltage present for

min. 25% -max. 75% of

interrupt rate period.

Audio warning (not

Same as J21, pin C.

used)

Audio warning tone

Same as J21, pin C;

No. 3

except 18.5 ±2 Vac into

100 ohm load.

Audio tone

Airframe ground

Presence of this input is required for outputs

enable ground

at J21, pins C and D.

Supply input

+28 Vdc

voltage

Presence of these inputs required for all EPO unit outputs.

Ground

Airframe ground

NR tach gen

Ac voltage, 68.6

Same as above

±0.7 Hz, or less

Same as above

Audio warning tone

Same as J21, pin C;

No. 3

except 18.5 ±2 Vac into

100 ohm load.

Same as above

N_R sensing

Airframe ground

Presence of this input is required to prevent

and audio

outputs at J21, pins F, K and M with input at

tone No. 3

pin L. (3)

disable

NOTE:

(1) All ac voltage levels are peak-to-peak on calibrated oscilloscope.

(2) N₁ and N_R sensing inputs produce all associated outputs listed, when other required indicated inputs are

present.

(3) At removal and reapplication of input at pin G, output at G, outputs occur 3.5 seconds after reapplication

due to internal time-delay circuits.

Page 17-64

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

PRESS−TO−TEST SWITCH

+28 VDC IN

GND IN

CR14

START PUMP

ON LAMP

CR15

GROUND

START PUMP IN

CR3

CR4

(+28 VDC)

+28 VDC IN

CR1

BRIGHT−

CR2

ENG OUT

DIM RELAY

LAMPS DIM GND

LAMPS

K−1

CONTROL IN

START PUMP

LAMPS VARIABLE

ON LAMP

DIM CONTROL IN

CR6

CR7

CR5

ENGINE OUT

PULSATING

XMSN OIL TEMP

+DC V IN

AND PRESS

LAMPS

XMSN OIL TEMP

AND PRESS

CR8

PULSATING

+DC V IN

*XMSN OIL TEMP

AND PRESS IN

VR1

CR10

CR11

CR12

CR13

CR9

*ENG CHIP

CHIP DET LAMP

DETECTOR IN

*FUEL LOW HI

FUEL LOW LAMP

*FUEL FILTER IN

FUEL FILTER LAMP

*GEN OUT IN

GEN OUT LAMP

LAMPS

PANEL LAMPS

(CHIP DET,

V OUT

FUEL LOW,

FUEL FILTER

NOTES:

AND GEN OUT)

REFERENCE DESIGNATORS ASSIGNED FOR REFERENCE

COMMON

ONLY AND ARE NOT ON COMPONENTS.

ASTERISK ( * ) INDICATES NEGATIVE (GROUND) FAULT INPUT.

ALL CONNECTOR PINS ARE PART OF SINGLE CONNECTOR

ON UNIT.

30−196

Figure 17-20. Grimes 70-0054-1 Indicator Dimming Assembly Schematic Diagram

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

P/O

FAULT

CR9

P/O

INPUT

BRT

CHIP DET

VR1

+28 VDC

PRESS−TO−TEST

DS3 (NOTE 7)

DIM

CR1

CR10

NEG TEST

P/O

CR2

NOTE 1

BRT

DIM

NEGATIVE (GRD) FAULT INPUT CAUTION INDICATOR LIGHTS

(TYPICAL FOR CHIP DETECTOR, FUEL LOW, FUEL FILTER AND GENERATOR OUT)

P/O

(DIM)

+28 VDC FROM

FUEL PUMP CB

START PUMP

CR15

ON DS7

(BRT)

PRESS−TO−TEST

(NOTE 7)

+28 VDC

POS

CR14

TEST

BRT

+28 VDC

DIM

CR1

P/O

CR2

NOTE 1

BRT

DIM

POSITIVE (+28 VDC) INPUT WARNING LIGHTS

(TYPICAL FOR START PUMP ON AND XMSN OIL TEMP AND PRESS)

P/O

PULSATING +VDC

INPUT FROM EPO UNIT

BRT

P/O

CR6

ENG OUT DS1

PRESS−TO−TEST

P/O

(NOTE 7)

DIM

+28 VDC

POS

CR3

TEST

+28 VDC

CR1

BRT

CR2

NOTE 1

DIM

POSITIVE (+28 VDC) INPUT WARNING ENG OUT LIGHT

P/O

+28 VDC

P/O

+28 VDC

BRT

R113

CR16

(NOTE 7)

CR5

OFF

NOTE 1

EXTERNAL

PANEL LAMPS

(NOTE 1)

PANEL LIGHTS DIMMING

NOTES:

DIM−BRT SWITCH AND R113 ARE MECHANICALLY LINKED. PANEL LAMPS,

EACH CIRCUIT SHOWS ONLY COMPONENTS USED FOR

DIM−BRT SWITCH AND R113 ARE PART OF OPTIONAL NIGHT LIGHTING

FUNCTION INDICATED.

SYSTEM.

ALL COMPONENTS WITH REFERENCE DESIGNATORS ARE PART

REFER TO ELEC SYSTEM SCHEMATIC AND WIRING DIAGRAMS (REF. SEC 20)

OF DIMMER ASSY UNLESS OTHERWISE INDICATED.

FOR FAULT AND FUNCTION INPUT SOURCES, INTERCONNECTING WIRING

REFERENCE DESIGNATORS ARE FOR REFERENCE ONLY AND

INFORMATION AND DIMMER ASSY SCHEMATIC DIAGRAM.

ARE NOT ON COMPONENTS.

DASHED LINE WITH ARROWHEAD ( − − − ) INDICATES CURRENT PATH

NOT PART OF DIMMER ASSY.

(OPPOSITE OF VOLTAGE) THROUGH INDICATOR LAMPS.

30−167A

Figure 17-21. Caution and Warning Indicating Light System Dimming Circuits

(Instrument Panel Type A)

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Negative (Ground) Input Fault Caution

E. Engine Out warning Light and Horn

Light Indicator Circuits

Circuit

(Ref. Figure 17−23) The ENG OUT warning

(Ref. Figure 17−23) Negative input fault

light and audible horn functions when the

caution light indicator circuits function when a

engine out frequency sensor circuit in the

ground is applied from external sensing switch

engine power out waning control unit is

to the dimmer assembly.

actuated by a decrease of engine speed to a

specific value of N₁ rpm.

When the ground is applied, a current path is

completed from the external ground through

When this occurs, a pulsating dc voltage input

the associated external caution lamps and

from the sensor circuit is applied through

PANEL LT circuit breaker CB104 to the +28

diode CR 7 to and flashes the ENG OUT

Vdc source.

lamps. Simultaneously, the pulsating dc

voltage is applied to and activates the audible

A diode (CR11 or other diode, as applicable) is

warning horn DS105 by means of the circuit

provided for each individual negative input

through part of the closed generator (GEN)

fault circuit for use in the press−to−test

switch S4.

circuits.

When open, GEN switch, GEN switch S4

C. Negative (Ground) Input Fault Warning

disables the audio warning horn. Diode CR3 is

Light Indicator Circuits

provided for use in the press−to−test circuits.

(Ref. Figure 17−23) Negative input fault

F. Panel and Instrument Lights Dimming

warning light indicator circuits for the XMSN

Circuit

high OIL TEMP and/or low OIL PRESS lamps

(Ref. Figure 17−23) When the night lighting

function when a ground is applied from the

system is installed, a variable positive dc

associated sensor switch to the dimmer

voltage (0 to +28 Vdc) from the external

assembly.

FLIGHT instrument light potentiometer R110

is applied to the input of the switching

When the ground is applied, a current path is

regulator in the dimming assembly.

completed through the external warning

indicator lamps and a diode CR5 (or CR6) to

The variable input voltage causes the switch−

the transmission oil and temperature light

ing regulator to vary the positive dc output

flasher circuit of the engine power out warning

voltage applied to and current panel and

control unit. A pulsating dc voltage is applied

instrument cluster lamps.

to and flashes the warning indicator lamps. A

diode CR9 (or CR10) is provided for each of the

The control panel and instrument internal

two negative input fault circuits for use in the

illumination.

press−to−test circuits.

Minimum regulator output voltage is +2.5 Vdc

D. Positive (+28 Vdc) Input Start Pump

with an input o 0 Vdc and +26 Vdc with an

Warning Light Circuit

input of +28 Vdc.

G. Caution and Warning Lights

(Ref. Figure 17−23) The START PUMP

Press-T o-T est Circuits

warning light circuit functions when an

external +28 Vdc input is applied through

(Ref. Figure 17−23) Diodes are incorporated in

diode CR8 to the external START PUMP

the dimmer assembly for all of the caution and

warning lamp.

warning light circuits to provide either a

required ground or +28 Vdc input for the

The input is applied when the start pump is

associated circuit when the external PRESS−

energized by the START PUMP circuit breaker

TO−T est switch is depressed.

CB 118 on the instrument panel.

Lamp illumination is constant during press−

Diode CR4 is provided for use in the press−to−

to−test operation; none of the lamps flash

test circuits.

during the check.

Page 17-67

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

H. Autronics 2245-1 Dimmer Assembly Test

26. Engine Power Out (EPO) Audio Amplifier

and Repair

(Used with Vapair EPO Warning Control

Unit)

(Ref. Figure 17−22)

The EPO audio amplifier is a solid state

amplifier that amplifies the audio signal from

(1). Test diodes, using an ohmmeter at

the EPO warning unit for application to radio

electrical connector pins. Check for low

headset(s).

forward resistance with positive lead

applied to the anode and negative lead

The amplifier is a sealed in a cylindrical

applied to the cathode. Read very back

container, with a wiring harness and attached

resistance when leads are reversed.

connector secured to each end.

(2). Test switching regulator by applying

The early type amplifier is an Autronics

+28 Vdc at electrical connector pin V

2037−1 two−transistor, dual channel amplifier;

and ground at pin W. Check output at

however, only one channel is used. The power

pin d for 2.5 Vdc minimum. Apply +28

gain ratio of the dual channel amplifier is 3 to

Vdc at pin d for 26 Vdc minimum.

1 greater, when used with the EPO warning

unit.

(3). Replace faulty internal components.

For the current type, two−transistor, single

I. Autronics 2245-1 Dimmer Assembly

channel amplifier, a 2 milliwatt input input

Replacement

produces a 100 milliwatt minimum output.

Refer to the electrical system wiring diagram

(Ref. Figure 17−22)

(Ref. Sec. 20) for inter−connecting wiring

information.

(1). Check that electrical power is OFF.

A schematic diagram for both early and

(2). Locate dimmer assembly mounted

current type units is provided in Figure 17−24.

forward of the ash tray in the lower

Both the single and dual channel amplifier

switch/circuit breaker panel box.

interconnect with the electrical system

identically.

(3). Disconnect plug at the front of the

dimmer assembly.

The amplifier also contains straight through

circuits, not interconnected to the internal

(4). Remove four screws attaching dimmer

amplifier circuit, that transfer all inputs and

to lower surface of panel box and

outputs to and from the EPO warning unit.

remove dimmer.

The EPO audio amplifier is installed with the

EPO warning unit at the lower right interior of

(5). Install replacement dimmer by essen−

the instrument panel console.

tially reversing the above procedure.

A. EPO Audio Amplifier Replacement

(6). Connect electrical power and check

caution and warning light PRESS−TO−

(Ref. Figure 17−3) Accomplish replacement of

TEST operation.

the audio amplifier according to the instruc−

tions in Replacement of Vapair 26530332M

NOTE: If any single caution or warning light

EPO Warning Control Unit except disconnect

does not illuminate and N₁ sensing equip−

both electrical plugs of the amplifier and

ment is used, try pressing the legend face of

remove only the upper aft screw from the

the indicator to be sure that the internal

engine power out control unit case to release

switch and lamps are not defective.

the amplifier.

(7). Check instrument panel lights for

NOTE: The single channel amplifier is used for

proper dim and bright operation. Turn

replacement and is one− way interchange−

off electrical power.

able with the dual channel amplifier.

Page 17-68

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

J12

+28 VDC

CR1

CR2

CR3

CR4

CR5

CR6

PRESS. AND TEMP WARN. SIGNAL

XMSN OIL TEMP LT/SW HI

XMSN OIL PRESS. LT/SW HI

CR7

ENGINE OUT WARN. SIGNAL

ENGINE OUT LT/SW HI

CR8

START PUMP HI

START PUMP LIGHT HI

XMSN OIL TEMP SWITCH

CR9

XMSN OIL TEMP LT/SW LO

XMSN OIL PRESS. SWITCH

CR10

XMSN OIL PRESS. LT/SW LO

ENGINE CHIPS LT/SW LO

CR11

ENGINE CHIP DETECTORS

GEN OUT LT/SW

CR12

GEN OUT ALARM

FUEL LOW LT/SW LO

CR13

FUEL LOW SWITCH

FUEL FILTER LT/SW LO

CR14

FUEL FILTER SWITCH

M/R XMSN CHIPS LT/SW LO

CR15

M/R XMSN CHIP DETECTOR

T/R XMSN CHIP LT/SW LO

CR16

T/R XMSN CHIP DETECTOR

DC GROUND TEST

DC GROUND

28 VDC

SWITCHING

REGULATOR

DIMMER POT ARM

PANEL LIGHTING, VARIABLE DC

NOTES:

TERMINALS NOT DESIGNATED WITH LIGHT SWITCH (LT/SW) ARE INPUTS

FROM SENSOR/SENDER UNITS, UNLESS OTHERWISE INDICATED.

TERMINALS DESIGNATED WITH LIGHT SWITCH (LT/SW) ARE OUTPUTS

TO CAUTION AND WARNING LIGHTS.

TERMINALS DESIGNATED DC GROUND TEST AND +28 VDC ARE INPUTS

FROM PRESS−TO−TEST SWITCH.

TERMINAL DESIGNATED DIMMER POT ARM IS INPUT FROM PANEL

LIGHTS DIMMING CONTROL.

TERMINAL DESIGNATED PANEL LIGHTING, VARIABLE DC IS OUTPUT

TO PANEL AND INSTRUMENT LIGHTS.

DIODES CR5 THRU CR8 USED IN WARNING LIGHTS FLASHING CIRCUITS.

ALL OTHER DIODES USED ONLY IN PRESS−TO−TEST CIRCUITS FOR LIGHT INDICATORS.

30−187A

Figure 17-22. Autronics 2245-1 Dimmer Schematic Diagram (Instrument Panel Type B)

Page 17-69

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ROTOR OIL

TEMP SWITCH P/O

P/O

FAULT

S202

P9J

P12

INPUT

PULSATING +VDC IN

3 URLLULLR

FROM EPO UNIT

XMSN OIL TEMP

P/O ENG OUT

LT/SW DS12

PRESS−TO−TEST

LT/SW DS14

(NOTE 2)

SWITCH

CR9

P/O

TB6

NEGATIVE (GND) FAULT INPUT WARNING INDICATOR LIGHTS

P/O GEN OUT

+28 VDC

(TYPICAL FOR MAIN XMSN OIL TEMP AND OIL PRESS)

LT/SW DC18

PANEL LT

CB104

T/R XMSN

P/O

PANEL LT

CHIP DET P402J

P9J

CB104

J12

T/R XMSN

CHIPS

+28 VDC

LT/SW DS20

P/O M/R

P/O ENG

P/O GEN

XMSN

CHIPS

OUT

P/O ENG

CR11

CHIPS

LT/SW

OUT LT/SW

LT/SW

DS15

DS18

DS14

DS19

P/O

NEGATIVE (GND) FAULT INPUT CAUTION INDICATOR LIGHTS

TB6

PRESS−TO−TEST

(TYPICAL FOR ENG CHIPS, GEN OUT, FUEL LOW, FUEL FILTER,

SWITCH

M/R XMSN CHIPS AND T/R XMSN CHIPS)

START

PUMP

P/O

PUMP

P/O

CB118

J24P

LT DS7

P23J

TB6

P12

+28 VDC

CR8

TO START

PUMP

+28 VDC

PANEL LT

CR4

CB104

P/O GEN

P/O

OUT LT/SW

PRESS−TO−TEST

DS18

SWITCH

POSITIVE (+28 VDC) INPUT WARNING LIGHT (START PUMP)

NOTES:

CIRCUITS SHOWN ARE TYPICAL. VARIATIONS MAY EXIST

COMPONENTS CONNECTED BETWEEN CONNECTOR P12 PINS

FROM THAT SHOWN ACCORDING TO HELICOPTER MODEL

ARE PART OF DIMMER ASSEMBLY.

AND SERIAL NO. (REF. NOTE 5).

FOR FAULT AND FUNCTION INPUT SOURCES NOT SHOWN AND

FOR INTERNAL CIRCUITS OF ALL LIGHT/SWITCHES, SEE

INTERCONNECTING WIRING INFORMATION, SEE APPLICABLE

CIRCUIT FOR XMSN OIL TEMP LT/SW DS12. IT IS TYPICAL

ELECTRICAL SYSTEM SIRING DIAGRAM (REF. SEC. 20).

FOR ALL LIGHT/SWITCHES. LIGHTS WITHOUT SWITCHES

FOR COMPLETE CIRCUIT INFORMATION ON DIMMER ASSEMBLY,

DIFFER (REF NOTE 5).

SEE SCHEMATIC DIAGRAM FOR DIMMER ASSEMBLY IN THIS

EACH CIRCUIT SHOWS ONLY COMPONENTS USED FOR

SECTION.

FUNCTION INDICATED.

30−197−1A

Figure 17-23. Caution and Warning Indicating Lights System Circuits

(Instrument Panel Type B) (Sheet 1 of 2)

Page 17-70

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

P/O GEN

P/O

SW S4

P12

PULSATING DC V IN

FROM EPO UNIT

−

AUDIBLE WARNING

HORN DS105

P/O

P12

TB6

CR7

P/O GEN OUT

PANEL LT

ENG OUT

LT/SW DS18

CB104

CR3

LT/SW DS14

+28 VDC

P/O

PRESS−TO−TEST

SW S1

ENGINE OUT WARNING LIGHT AND HORN

P/O

PANEL LTS

P12

TB502−6

TB502−7

+28 VDC

PANEL LT

CB104

SWITCHING

REGULATOR

+28 VDC

(NOTE 9)

INSTRUMENT

P/O

CLUSTER LTS

TB6

P/O

TB6

PANEL AND INSTRUMENTS LIGHT DIMMING

NOTES: (CONT)

ABBREVIATIONS:

BRT − BRIGHTNESS

LL − LOWER LEFT

LR − LOWER RIGHT

LT − LIGHT

M/R − MAIN ROTOR

P/O − PART OF

SW − SWITCH

T/R − TAIL ROTOR

UL − UPPER LEFT

UR − UPPER RIGHT

XMSN − TRANSMISSION

DASHED LINES WITH ARROWHEAD ( − − ) INDICATES CURRENT

PATH (OPPOSITE OF VOLTAGE) THROUGH CIRCUITS.

INPUT (P12−X):

0 − +28 VDC.

OUTPUT (P12−d): +2.5 VDC MINIMUM WITH 0 VDC INPUT.

+26 VDC MINIMUM WITH +28 VDC INPUT.

30−197−2A

Figure 17-23. Caution and Warning Indicating Lights System Circuits

(Instrument Panel Type B) (Sheet 2 of 2)

Page 17-71

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

P13

AR500 AUDIO AMP

(P7)

XMSN HI OIL TEMP K

WHT

GEN SW GND H

BLK

ENG OUT LAMP F

YEL

*C1

0.1

*HEADSET AUDIO D

*BLU

2N697

#2 IN

(2N3053)

R1 (R3)

1.5 K

GROUND E

ORN

R3 (R1)

C3 (C1)

1.5 K

0.1

HEADSET AUDIO C

GRN

2N697

#1 IN

R4 1K (530)

+28 VDC OUT B

RED

R2 1K

N1 TACH GEN V A

VIO

*C2

C4 (C3)

(C2) (0.1)

0.47

(6.8)

VIO

RED

*GRN

ORN

BLU

YEL

BLK

WHT

(GRN)

D (C)

+28 VDC

*HEADSET

GROUND

HEADSET

ENG

GEN

XMSN

TACH

AUDIO #1

AUDIO #2

OUT

HI OIL

GEN V

OUT

LAMP

GND

TEMP

(HEADSET

AUDIO #1

OUT)

NOTES:

ASTERISK ( * ) INDICATES ITEM APPLIES ONLY TO DUAL CHANNEL AMPLIFIER.

UNLESS OTHERWISE NOTED, SOLID LINES APPLY TO BOTH DUAL AND

SINGLE CHANNEL AMPLIFIERS.

DASHED CIRCUIT LINES ( − − − ) AND ITEMS IN PARENTHESIS ( ) APPLY ONLY

TO SINGLE CHANNEL AMPLIFIER.

RESISTANCE VALUES IN OHMS AND CAPACITANCE VALUES IN MICROFARADS.

30−169A

Figure 17-24. Audio Amplifier (Dual and Single Channel) Schematic Diagram

Page 17-72

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

27. Engine Power Out (EPO) Audible Warning

(7). Install replacement horn, housing and

Horn

fairing in reverse order of removal. For

electrical wiring interconnect informa−

The EPO audible warning horn is an electro−

tion, refer to Section 19.

mechanical warning unit that produces an

audible ‘‘beeping" sound in the pilot’s compart−

(8). Perform an operational check of the

ment when engine N_l speed decreases below

audible warning horn.

approximately 55% N_l rpm, or N_R speed

decreases to 98% rpm or less for N₁/N_R sensing

28. N_R Disable Switch

equipment.

(Ref. Figure 17−25) N_R disable switch S199 is

The audible warning horn is installed at either

mounted on the inboard collective stick socket

the upper left or right side of the instrument

on those helicopters with the N₁/N_R engine

panel (model difference only).

power out warning system.

On instrument panel type A and early type B,

The switch disables N_R (main rotor) speed

mounting of the original audible warning horn

sensing and prevents engine out warning

(Figure 17−1) is changed to that of the current

indications when the pilot’s collective pitch

instrument panel type B shown in

stick is in the full down position and the

Figure 17−2, due to required installation of

throttle is at idle.

battery temperature sensing equipment.

The audible warning horn is mounted in a

These control positions are normal during

lights/switch and horn housing on the side of

engine starting, idling, autorotation flight and

the raised top of the center instrument panel

engine shutdown when an engine out warning

fairing, with two battery temperature caution

is not desired.

and warning light/switch indicators.

NOTE: On helicopters originally equipped with

An early type audible warning horn installa−

N₁ sensing equipment that has been modi−

tion uses a modified Edwards 319 horn;

fied to N₁/N_R sensing equipment, N_R disable

current type incorporates a modified Mallory

switch installation may differ slightly from

SC628 ‘‘Sonalert’’ unit.

that shown. (Refer to CSP−3 for differences

and for instructions for modification of such

A. Edwards Audible Warning Horn

an installation to the current type N_R dis−

Replacement

able switch installation.)

(1). Check that all electrical power is off.

A. N_R Disable Switch Replacement

(2). Remove instrument panel side fairings

(1). Remove center seat cover and controls

as necessary for access to internal

access door.

wiring.

(2). Check that electrical power is off.

(3). Loosen and remove attachment hard−

Disconnect wire E105B20N at ground

ware securing instrument panel center

terminal and wire E105A20 at splice.

fairing to free it sufficiently for partial

Cut all tie straps attaching wires to

access.

inboard collective stick socket

(Figure 17−25).

(4). As necessary, remove attaching hard−

ware and disconnect electrical wiring to

(3). Remove the switch by removing the two

permit removal of the lights/switch and

screws and the threaded attach plate.

horn housing (Figure 17−24).

(5). Remove lights/switch and horn housing

(4). Remove the switch attaching bracket by

from center fairing.

loosening the two upper bolts in the

inboard collective stick socket housing

(6). Disassemble horn housing; remove horn

cap and slipping out the slotted attach−

from housing as shown in Figure 17−1.

ing bracket.

Page 17-73

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(5). Remove the switch actuating arm by

(4). If CHIPS indicator light does go on,

loosening the bolt in the gas producer

check that jumper is properly grounded.

bellcrank and slipping out the slotted

If so, check circuit components for

actuating arm. Remove the actuating

continuity and replace defective parts.

cam used in current installation by

removing the bolts in each end of the

30. Fuel Pressure Switch

gas producer bellcrank.

A. Fuel Pressure Switch Operational Check

(6). Install replacement components in

essentially reverse order of removal;

(1). Check that all electrical power is OFF;

adjust N_R disable switch.

disconnect battery.

B. N_R Disable Switch Adjustment

(2). Gain access to engine accessory section;

locate fuel filter (bypass) pressure

(1).

Check that pilot’s collective pitch stick

switch on front of engine driven fuel

is in full down position and throttle grip

pump.

rotated to idle position.

(3). Remove protective sleeving and

(2).

Position switch so that it activates

disconnect knife splice on bypass switch

(clicks) when the switch roller contacts

wiring.

the actuator cam.

(4). Disconnect and cap bypass hose

(3).

Note switch position at point of actua−

assembly at bushing.

tion and move switch toward actuator

cam an additional 0.030 inch (0.762

(5). Remove switch (with bushing fitting

mm). Tighten switch mounting screws

intact) from the after filter port (AF)

to secure switch in position and

engine driven fuel pump.

safetywire.

(6). Perform function test of bypass switch

(4).

Check that pilot’s throttle grip will

as follows:

rotate to cutoff position. Check pilot’s

collective pitch stick operation through

(a). Remove bushing and O−ring from

full range to determine that switch

bypass switch.

wiring does not interfere with move−

ment.

(b). Fabricate test set up (Figure 17−26).

(5).

Perform operational check of N_R disable

NOTE: Switch actuation (closing) pressure

switch and audible warning horn with

should be 24.5−35.0 inches (62.23−88.9 cm)

collective pitch stick full down and

of fuel.

throttle at idle position.

(c). Pressurize inlet port of switch by

NOTE: Audible warning horn should not be ac−

adding fuel to the tub; watch ohmme−

tivated when throttle is at idle.

ter or continuity tester for indication

of switch actuation.

29. Chip Detector Circuits Operational Check

(1). Turn on electrical power; use an

(d). Check switch diaphragm for leakage.

external power supply when possible.

Replace switch if leakage is noted.

(2). Disconnect electrical wiring and

(e). Reinstall bushing with new O−ring

temporarily connect a jumper wire from

on bypass switch.

detector connector plug pin or wire

terminal to an unpainted (grounding)

(7). Perform operation check of switch as

surface of the airframe or engine.

follows:

(3). Observe CHIPS indicator light. If light

(a). Remove cap from bypass hose and

is on, circuit tests properly; remove

reconnect bushing (with switch) in

jumper wire and reinstall wiring.

hose fitting.

Page 17-76

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

PRESSURE METHOD:

APPLY 8−9 PSIG (16.3−18.3 IN. HG.) TO CLOSE SWITCH. BLEED

OFF TO 4 PSIG (8.1 IN. HG.) TO OPEN SWITCH.

PORT A

36 IN. (91.5 CM)

SCALE

NOTE 2

OHMMETER

36 IN.

PORT B

3/8" TYGON TUBING

(91.5 CM)

CONTINUITY TESTER

(OR EQUIV.)

VACUUM METHOD:

APPLY 8−9 PSIG (16.3−18.3 IN. HG.) TO CLOSE SWITCH. BLEED

OFF TO 4 PSIG (8.1 IN. HG.) TO OPEN SWITCH.

PORT A

369D28144 FUEL FILTER

PRESSURE SWITCH

NOTE 1

FUEL FILTER

PRESSURE SWITCH

OHMMETER

PORT B

CONTINUITY TESTER

NOTES:

369H8144 FUEL FILTER

CONNECT GROUND TEST LEAD TO ONE OF

PRESSURE SWITCH

THREE SCREW HEADS ON THE HOUSING BODY.

CONNECT GROUND TEST LEAD TO ONE OF

SIX SCREW HEADS ON THE HOUSING BODY.

G28−0010A

Figure 17-26. Fuel Pressure Switch Test Set-Up

Page 17-77

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Plug adapter fitting with AN 814−2

filter bypass caution light when start

in after filter (AF) port. Connect

pump is activated.

jumper wire to ground bypass switch

B. Fuel Pressure Switch Replacement

to aircraft ground (E12).

(Ref. Figure 17−7)

(c). Have assistant hold switch clear;

connect battery or electrical power

(1). Disconnect Knife splice in electrical

supply and activate start pump.

wire at switch.

(d). Check caution indicator light (fuel

(2). Remove interconnect tube, fuel pres−

bypass) for illumination.

sure switch and O−ring from engine

fuel pump filter.

NOTE: If fuel filter bypass caution indicator

does not light, perform electrical trouble

(3). Install replacement switch and service−

shooting of caution and warning lights.

able O−ring in the after filter port of

the pump filter. Torque the switch to 40

(e). Check switch diaphragm through

−

50 inch−pounds (4.52 − 5.65 Nm),

open port for leakage. Replace switch

reinstall interconnect tube and connect

if leakage is noted.

knife splice.

(f). Shut off electrical power, start pump,

(4). Operate engine starting pump and

battery switch; disconnect battery or

check for fuel leakage.

power supply and jumper wire.

NOTE: If fuel filter bypass caution indicator

31. Running Time Meter

did not light and electrical system is not

The running time meter is basically an electric

faulty, install new fuel filter pressure switch

clock that provides an accurate record of

(with new O−ring) at bushing, and repeat

engine and/or transmission operating time in

operational check of switch.

hours and tenths of hours.

(8). Remove plug from adapter fitting fuel

The meter operates whenever an oil pressure

filter port (AF); install bypass switch

switch in the main transmission is closed by

with new O−ring on adapter fitting.

transmission operating oil pressure.

Torque switch to 40 − 50 inch−pounds

(4.52 − 5.65 Nm).

The meter receives 28 Vdc power from the

instrument 5 ampere circuit breaker. The

(9). Remove plug from bypass hose; recon−

circuit is completed to ground through the

nect bushing at bypass hose. Torque

normally open contacts of the transmission

bushing to 40 − 50 inch−pounds (4.52

pressure switch (S203).

− 5.65 Nm).

A second set of normally closed contacts in the

(10). Reconnect knife splice on switch and

switch operates the XMSN oil pressure

reinstall protective sleeving.

warning light when below normal operating

(11). Bleed fuel filter housing (Ref. Sec. 12

pressure exists.

for fuel system bleeding instructions).

The running time is installed in a cover panel

(12). Run up engine and perform operational

on the left side of the instrument panel

check of engine and fuel system; check

structure just below floor level and is visible

for leaks and non−activation of fuel

from outside the helicopter.

Page 17-78

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 18

HEATING AND VENTILATING SYSTEM

1. Heating System

Before high speed flight is per−

CAUTION

formed, ensure that all door

ventilator cutouts are positioned up, aft, or

The heating system is not installed as stan−

down (in the aft 120 degree arc). Door dam−

dard equipment. Refer to CSP−H−3 for

age and vibrations could occur if vent cut

information on the Cabin Heating Installation.

outs face airstream.

3. Ventilating Valve Control

2. Ventilating System

(Ref. Figure 18−1) The ventilating valve cable

is a flexible, coaxial−wire type that incorpo−

(Ref. Figure 18−1) The main fresh air source

rates a push−button locking device in the

for the cabin interior is a cable−actuated vent

control housing. This feature allows locking of

control valve located on the fuselage center−

the ventilating valve in the open, closed, or

line, recessed in the canopy panel forward of

any intermediate position.

the instrument panel.

The control assembly is not repairable. Failure

of the internal locking device is cause for

The vent control valve has a circular 4 inch

replacement.

(10.16 cm) inlet that supports the valve shaft

and control matching valve vane assembly.

A. Ventilating Valve Control Replacement

(1).

Ensure that electrical power is OFF.

The valve vane assembly is actuated by a

(2).

Disconnect cable wire from valve arm

push−pull control cable mounted in the right

swivel.

center of the instrument panel. The control

cable knob marked PULL FOR AIR is a

(3).

Remove screws, nuts washers and clip

friction catch type that locks the cable in any

securing cable to support bracket.

selected position throughout the full stroke

(4).

Remove instrument panel right side

when the knob plunger is released.

fairing.

(5).

Loosen and remove hex nut and

The vent control valve housing is formed of

lockwire securing cable knob to instru−

polycarbonate plastic.

ment panel and with drawn cable from

panel.

A single cylindrical duct on the rear of the vent

(6).

Route new cable through instrument

control valve directs air outward from both

panel and secure knob in place with

sides of the valve.

lock washer and nut.

(7).

Fasten cable sleeve to support bracket

On the early configuration, two polycarbonate

on valve and secure with clip, screws,

plastic ducts, attached to the rear of the valve,

washers and nuts.

direct inlet air through holes in sides of

console fairings for circulation through−out the

(8).

Actuate control knob to align cable wire

cabin interior.

with hole in valve arm swivel; push

knob to cable panel fitting stop.

Each pilot’s and cargo/passenger compartment

(9).

Position valve to full closed and tighten

door window contains adjustable ventilators

swivel on cable wire. Install cotter pin.

that can be opened, closed, and positioned by

rotation of the vent cutout, to supplement

(10).

Check swivel for free rotation by

fresh air intake or provide an air circulation

actuating control knob through full

exhaust outlet as desired.

stroke.

Page 18-1

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(11). Inspect valve assembly for complete

with 90 degree spacing to attach valve

closure of inlet opening when control

to duct. On the early configuration, if

knob is pushed forward against cable

rivet holes are elongated or over−size,

panel fitting stop.

install next larger size rivets (5/32 inch

diameter).

(12). Check valve door for looseness on shaft

(3).

Fasten cable sleeve to valve bracket

and deformation; valve door must be

with clip.

flat, and a firm, snug fit in the inlet.

(4).

Install swivel assembly loosely in arm

(13). Reinstall right side fairing on instru−

of shaft.

ment panel.

(5).

Insert control wire into swivel assem−

4. Cabin Ventilating Valve

bly.

(6).

Position shaft arm so that valve door is

(Ref. Figure 18−1) The cabin ventilating valve

fully closed.

is made of polycarbonate plastic and incorpo−

rates a valve vane assembly to control ventilat−

(7).

Push control knob all the way in then

ing air flow.

tighten swivel assembly on wire. Install

cotter pin.

The vane assembly consists of a seal bonded

around a circular aluminum vane.

(8).

Operate valve through several open−

close cycles to assure ease of operation

The valve assembly is attached by four screws,

and to determine that valve locks in

washers, and nuts to a duct molded into the

any position when control knob is

fiberglass canopy panel.

released.

(9).

On early configuration, install ducts on

On the early configuration, the valve is

rear of vent control valve.

attached with four rivets.

(10).

Install instrument panel left and right

A. Ventilating Valve Removal

side fairings

(1). Remove instrument panel left and right

C. Ventilating Valve Inspection

side fairings.

(1). Inspect plastic walls for cracks, secure

(2). On the early configuration, remove

attachment to the canopy panel and

ducts from rear of vent control valve.

separation of bonded joints. (Very small,

widely separated spots or voids in the

(3). Remove cable clip.

plastic joints are not separation but air

pockets produced during the solvent

(4). Pull cable control to open valve door.

bonding process.)

(5). Loosen swivel assembly and disconnect

(2). Inspect for bent shaft or valve vane

control cable.

assembly and excessive shaft wear in

the pivot areas.

(6). Remove four screws, washers and nuts

(3). Inspect seal on vane assembly for wear.

that attach valve to canopy panel duct.

On the early configuration, drill out the

D. Ventilating Valve Disassembly

four rivets.

(1). Remove two screws from shaft and vane

(7). Remove valve assembly.

assembly. Slide vane assembly from

shaft.

B. Ventilating Valve Installation

(2). Remove cotter pin and washer and slide

(1). Position valve on canopy panel duct and

shaft from valve body.

align screws or rivet holes, as applica−

E. Ventilating Valve Reassembly

ble

(1). Install cotter pin in hole at control arm

(2). Install four screws, washers and nuts

end of shaft. Install washer on shaft to

(or MS20470A rivets, as applicable)

bear on cotter pin.

Page 18-2

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(2). Insert shaft in body of valve.

5. Door Window Ventilators (Snapvents)

(3). Insert valve vane assembly into slot in

(Ref. Figure 18−1) Plastic snapvents are

shaft.

installed in each of the four door windows.

These units may be rotated in their reinforced

(4). Install two screws through vane and

window holes for intake or exhaust of ventilat−

shaft using loctite (29, Table 2−4).

ing air or may be pulled in ward for completed

(5). Install washer on end of shaft and

closure. Damaged snapvents should be

insert cotter pin.

replaced; repair is not practical.

(6). Operate valve several times to assure

A. Window Snapvent Replacement

freedom and positive closing.

(1). Push snap vent outward in window

F. Ventilating Valve Repair

(open position).

(1). Repair polycarbonate valve body cracks

(2). Grasp the open side of the snapvent

by binding a patch according to the

and gently squeeze it into an elliptical

criteria and methods specified for

shape.

acrylic plastic in FAA AC 43.13−1,

Aircraft Inspection and Repair. Use

(3). Slip snapvent out of window hole at

dichloromethane (38, Table 2−4) or

about a 30 degree angle to surface of

ethylene dichloride as the bonding

window.

agent.

(4). Hold the open end of the replacement

(2). Repair small areas of rib or seam

snapvent and gently squeeze it into an

separation by injecting ethylene

elliptical shape.

dichloride (39) into the void area and

clamping together under light pressure.

(5). Slip snapvent flange into window hole

(3). Replace unserviceable seal, using

at an angle of about 30 degrees to the

adhesive (69) according to container

surface of the window. Be sure the ends

instructions.

of wire stiffener are inside window hole.

Page 18-3

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 19 Electrical System .

19−1

Power Supply and Distribution

19−1

Power Supply and Distribution System Troubleshooting . .

19−1

Electrical System Load Chart

19−1

Figure 19−1. Arrangement of Electrical System Switches and

Circuit Breakers

19−2

Table 19−1. Basic Equipment Electrical Load Analysis Chart .

19−3

Table 19−2. Optional Equipment Electrical Load Analysis Chart .

19−6

Figure 19−2. Electrical System Load Analysis

19−9

Table 19−3. Troubleshooting Dc Power Distribution

19−11

Wiring Harnesses

19−13

A. Wire Harness Replacement

19−13

Electrical Connectors

19−13

A. Plug/Socket Connector Repair or Replacement

19−13

Figure 19−3. Repair or Replacement of Rectangular Electrical Connectors .

19−14

B. Disconnection/Connection of Wire Mate Connectors

19−15

C. Minilok and Modulok Terminal Block Contact Tip Replacement .

19−15

Figure 19−4. Identification and Replacement of Burndy Terminal Block

Modules

19−16

D. Minilok and Modulok Terminal Block Replacement

19−17

E. Electrical Bonding Connector Maintenance

19−17

Figure 19−5. Typical Requirement for Electrical Bonding Connections .

19−18

F. External Power Receptacle Replacement

19−19

Electrical Equipment

19−19

Voltage Regulator

19−19

A. Voltage Regulator Replacement

19−19

Figure 19−6. Electrical Equipment (Cabin Locations)

19−20

B. Installed Voltage Regulator Adjustment

19−21

Figure 19−7. Voltage Regulator Test Points

19−21

Table 19−4. Recommended Voltage Setting

19−21

C. Voltage Regulator Bench Testing

19−22

Overvoltage Relay

19−22

A. Overvoltage Relay Replacement

19−22

Figure 19−8. Test Hookup for Voltage Regulator

19−23

Figure 19−9. Electrical Equipment Locations (Instrument Panel Type A) .

19−24

Figure 19−10. Electrical Equipment Locations (Instrument Panel Type B) .

19−25

Circuit Breaker Panel

19−26

A. Circuit Breaker Replacement

19−26

Page 19−i

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

10. Control Switches

19−26

A. Control Switch Replacement

19−26

Table 19−5. Resistor Reference Designator

19−27

11. Voltage Reduction and Calibration Resistors

19−27

A. Voltage Reduction and Calibration Resistor Replacement .

19−27

12. Start Relay

19−27

A. Start Relay Replacement

19−27

Figure 19−11. Replacement of Engine Compartment Relays .

19−28

13. Reverse Current Relay

19−29

A. Reverse Current Relay Replacement

19−29

14. Battery Relay

19−29

A. Battery Relay Replacement

19−29

B. Battery Relay Troubleshooting

19−29

15. APU Relay

19−29

A. APU Relay Replacement

19−29

B. APU Relay Troubleshooting

19−30

16. Collective Pitch Stick Switches

19−30

A. Collective Pitch Stick Switch Replacement

19−30

Figure 19−12. Replace of Collective Pitch Stick Switches .

19−31

17. Battery Temperature Sensing Equipment

19−32

A. Battery Temperature Sensing Equipment Maintenance . .

19−32

B. Battery Temperature Sensing Equipment Operational Check .

19−32

Figure 19−13. Battery Temperature Sensing Equipment .

19−33

18. Battery

19−34

A. Battery Maintenance

19−34

B. Battery Replacement

19−34

Figure 19−14. Replacement of Battery Components

19−35

C. Battery Inspection

19−36

D. Testing of Battery Temperature Sensing Switches

19−36

E. Repair of Battery

19−36

19. Starter/Generator

19−38

A. Starter/Generator Removal

19−39

B. Starter/Generator Inspection

19−39

Figure 19−15. starter/generator Replacement and Repair . .

19−40

Figure 19−16. Starter/Generator Bushing Wear Limits

19−41

C. Starter/Generator Repair

19−41

Figure 19−17. Test Hookup for Starter/Generator and Brush Run−in

19−43

Page 19−ii

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SECTION 19

ELECTRICAL SYSTEM

1. Power Supply and Distribution

equipment enclosure to the structure. Current

path return and static charge bonding jumpers

The electrical system consists of all electrical

are also installed at appropriate locations.

power supply, distribution and control equip−

ment, wiring and miscellaneous associated

NOTE: On all current models of the 500 Series

equipment supplied as standard on the

helicopters, electrical systems are standard

helicopter.

and essentially identical, except in instru−

ment/electrical controls console area for dif−

The electrical system is supplied by a 28−volt

ferent models. (Electrical components, com−

direct current, 150−ampere, engine−driven

ponent locations, installation, wiring, etc.

generator in conjunction with a 24−volt

throughout the helicopters are basically

nickel−cadmium battery and incorporates an

identical, except for those areas specified.)

external power receptacle. The system is a

Any differences that exist in these areas

nominal 28 Vdc, single−wire type installation

from the electrical system outlined in this

with helicopter structure used as the ground

section are described in the applicable HMI

return.

Supplement for that specific model helicop−

ter.

Control of the electrical system, exclusive of

optional intercom controls, is provided by the

2. Power Supply and Distribution System

switches and circuit breakers on the instru−

Troubleshooting

ment panel (Ref. Figure 19−1). All circuits of

the electrical system are protected by push−to−

(Ref. Table 19−3)

reset or switch−type circuit breakers. All

electrical or electronic units or components

3. Electrical System Load Chart

that produce electromagnetic energy (rf

potential) are bonded to the adjacent structure

Refer to Table 19−1, Table 19−2 and

to ensure a continuous, negligible radio

Figure 19−2 for electrical system load analysis

frequency (rf) impedance path from the

data.

Page 19-1

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-1. Basic Equipment Electrical Load Analysis Chart

PRE−START

START TURBINE

TAKEOFF & CLIMB

AMPS

DAY

NIGHT

EQUIPMENT

PART

PER

OPER

AVG. AMPS.

BASIC SHIP

DESIGNATION

UNITS

UNIT

TIME

SYS

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

FLIGHT CONTROLS

ACT−CYCLIC TRIM

(LONG. / LAT.)

369A7001

1.0

(6)

INSTRUMENTS

(OTHER THAN ENG. / FLT.)

HOUR METER

369H90027

0.1

INSTRUMENTS ENGINE

(3 PACK)

FUEL QUANT.

OIL TEMP.

( 2 )

369H6417

SYS

0.5

AMMETER

ENGINE−OUT WARNING SYSTEM

369H4540−BSC/−3

0.5

ENGINE−OUT WARNING LTS.

ENG. OUT

1041HS7−3

0.04

( 6/10 )

XMSN OIL PRESS.

( 14 )

1041HS7−4

0.04

( 6/10 )

XMSN OIL TEMP.

( 14 )

1041HS7−5

0.04

( 6/10 )

CHIP DET. ENG.

( 15 )

1041HS7−6

0.04

( 6/10 )

CHIP DET. T/R

( 15 )

1041HS7−7

0.04

( 6/10 )

CHIP DET. M/R

( 15 )

1041HS7−8

0.04

( 6/10 )

FUEL FILTER

1041HS7−11

0.04

( 6/10 )

GEN. OUT

1041HS7−10

0.04

( 6/10 )

FUEL LOW

1041HS7−9

0.04

( 6/10 )

INSTRUMENTS − FLIGHT

SEE OPTIONS

HEATING & VENTILATION

SEE OPTIONS

EXCITER (ALLISON)

6870058

1.0

2 ( 6 )

1.0

ENGINE CONTROLS

ACTUATOR − N₂ GOV.

369A7002

1.2

STARTER (GENERATOR)

369H4550

SYS

−

( 12 )

(12)

LIGHTING

ANTI−COL (STROBE) LTS.

369H90062−519

SYS

2.8

POS. LTS. (L, R & TAIL)

369H90062

SYS

3.0

INSTR. & PNL LTS. (327)

369H90062

SYS

( 17 )

LANDING LT. (MS25241−4581)

369H90062

SYS

16.0

MAP LT (HE/HS),

UTILITY LT (HM)

( 1309 )

369H90062

0.3

CONVENIENCE LT. (REAR)

( 1309 )

369H90062

0.3

DIMMER (AUTRONICS)

369H6425

SYS

2.5

CIGAR LIGHTER (C75Z1505A2 FORD)

369H6508

7.7

( 6 )

POWER

369H4115

BATTERY CHARGING

( 18 )

369A4540

( 4 )

40.0

30.0

40.0

30.0

OVER VOLTAGE RELAY

369A4557

0.2

( 5 )

REVERSE CURRENT RELAY

A700xA HARTMAN

0.5

VOLTAGE REGULATOR

369A4552

−

( 5 )

GENERATOR (STARTER)

369A4550

−

( 1 )

START PUMP

369A8143

SYS

3.5

BASIC SHIP AMPERES

2.8

9.3

8.3

44.4

34.4

66.5

56.5

Page

19-3

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-1. Basic Equipment Electrical Load Analysis Chart (Cont)

HOVER

CRUISE

DAY

NIGHT

DAY

NIGHT

EQUIPMENT

PART

AVG. AMPS.

BASIC SHIP

DESIGNATION

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

FLIGHT CONTROLS

ACT−CYCLIC TRIM

(LONG. / LAT.)

369A7001

INSTRUMENTS

(OTHER THAN ENG. / FLT.)

HOUR METER

369H90027

0.1

INSTRUMENTS ENGINE

(3 PACK)

FUEL QUANT.

OIL TEMP.

( 2 )

369H6417

0.5

AMMETER

ENGINE−OUT WARNING SYSTEM

369H4540−BSC/−3

0.5

ENGINE−OUT WARNING LTS.

ENG. OUT

1041HS7−3

XMSN OIL PRESS.

( 14 )

1041HS7−4

XMSN OIL TEMP.

( 14 )

1041HS7−5

CHIP DET. ENG.

( 15 )

1041HS7−6

CHIP DET. T/R

( 15 )

1041HS7−7

CHIP DET. M/R

( 15 )

1041HS7−8

FUEL FILTER

1041HS7−11

GEN. OUT

1041HS7−10

FUEL LOW

1041HS7−9

INSTRUMENTS − FLIGHT

SEE OPTIONS

HEATING & VENTILATION

SEE OPTIONS

EXCITER (ALLISON)

6870058

ENGINE CONTROLS

ACTUATOR − N₂ GOV.

369A7002

STARTER (GENERATOR)

369H4550

LIGHTING

ANTI−COL (STROBE) LTS.

369H90062−519

2.8

POS. LTS. (L, R & TAIL)

369H90062

3.0

INSTR. & PNL LTS. (327)

369H90062

LANDING LT. (MS25241−4581)

369H90062

16.0

MAP LT (HE/HS),

UTILITY LT (HM)

( 1309 )

369H90062

0.3

CONVENIENCE LT. (REAR)

( 1309 )

369H90062

0.3

DIMMER (AUTRONICS)

369H6425

2.5

CIGAR LIGHTER (C75Z1505A2 FORD)

369H6508

POWER

369H4115

BATTERY CHARGING

( 18 )

369A4540

30.0

23.4

17.0

30.0

23.4

17.0

30.0

23.4

17.0

30.0

23.4

17.0

OVER VOLTAGE RELAY

369A4557

REVERSE CURRENT RELAY

A700xA HARTMAN

0.5

VOLTAGE REGULATOR

369A4552

GENERATOR (STARTER)

369A4550

START PUMP

369A8143

BASIC SHIP AMPERES

34.4

27.8

21.4

56.5

49.9

27.5

34.4

27.8

21.4

40.5

33.9

27.5

Page 19-4

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-1. Basic Equipment Electrical Load Analysis Chart (Cont)

LANDING

EMERGENCY − GENERATOR OUT

DAY

NIGHT

DAY

NIGHT

EQUIPMENT

PART

AVG. AMPS.

BASIC SHIP

DESIGNATION

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

FLIGHT CONTROLS

ACT−CYCLIC TRIM

(LONG. / LAT.)

369A7001

INSTRUMENTS

(OTHER THAN ENG. / FLT.)

HOUR METER

369H90027

0.1

INSTRUMENTS ENGINE

(3 PACK)

FUEL QUANT.

OIL TEMP.

( 2 )

369H6417

0.5

AMMETER

ENGINE−OUT WARNING SYSTEM

369H4540−BSC/−3

0.5

ENGINE−OUT WARNING LTS.

ENG. OUT

1041HS7−3

XMSN OIL PRESS.

( 14 )

1041HS7−4

XMSN OIL TEMP.

( 14 )

1041HS7−5

CHIP DET. ENG.

( 15 )

1041HS7−6

CHIP DET. T/R

( 15 )

1041HS7−7

CHIP DET. M/R

( 15 )

1041HS7−8

FUEL FILTER

1041HS7−11

GEN. OUT

1041HS7−10

0.2

FUEL LOW

1041HS7−9

INSTRUMENTS − FLIGHT

SEE OPTIONS

HEATING & VENTILATION

SEE OPTIONS

EXCITER (ALLISON)

6870058

ENGINE CONTROLS

ACTUATOR − N₂ GOV.

369A7002

STARTER (GENERATOR)

369H4550

LIGHTING

ANTI−COL (STROBE) LTS.

369H90062−519

2.8

POS. LTS. (L, R & TAIL)

369H90062

3.0

INSTR. & PNL LTS. (327)

369H90062

LANDING LT. (MS25241−4581)

369H90062

16.0

MAP LT (HE/HS),

UTILITY LT (HM)

( 1309 )

369H90062

0.3

CONVENIENCE LT. (REAR)

( 1309 )

369H90062

0.3

DIMMER (AUTRONICS)

369H6425

2.5

CIGAR LIGHTER (C75Z1505A2 FORD)

369H6508

POWER

369H4115

BATTERY CHARGING

( 18 )

369A4540

OVER VOLTAGE RELAY

369A4557

REVERSE CURRENT RELAY

A700xA HARTMAN

0.5

VOLTAGE REGULATOR

369A4552

GENERATOR (STARTER)

369A4550

START PUMP

369A8143

BASIC SHIP AMPERES

4.4

26.5

4.1

26.2

10.2

Page

19-5

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-2. Optional Equipment Electrical Load Analysis Chart

PRE−START

START TURBINE

TAKEOFF & CLIMB

NO.

AMPS

DAY

NIGHT

EQUIPMENT

PART

PER

OPER

AVG. AMPS.

OPTIONS

DESIGNATION

UNITS

UNIT

TIME

SYS

MIN

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

ARMAMENT

SYS.

GYRO

ATTITUDE

369H90041−501

0.7

DIRECTIONAL

369H90042−BSC

0.7

DIRECTIONAL

369H90042−501

1.8

ANTI−COL−LTS

(QTZ IODINE 2 LTS)

369H90062

1.5

BOOM (QTZ 1 LT)

369H90062−515

1.5

POS−LTS BOOM

369H90062−513

1.8

CARGO HOOK

369H90065

14.0

( 6 )

HOIST

( 13 )

369H90070

35.0

( 6 )

RE−IGNITION−ENGINE

369H90118−501/−505

( 6 )

EMERGENCY FLOATS

369H92557

2.2

15 ( 7 )

HEATED PITOT TUBE

369H90034

1.3

HEATING − CABIN

369H90020

1.1

( 6 )

HEATING − ANTI−ICE

369H90020

0.3

( 6 )

VHF COMM (TRANS) RT−221AE−28

369H90064−3

3.9

( 8 )

VHF COMM (REC) RT−221BE−28

369H90064−5

1.1

VOR−VHF (NAV) RN−222AE−28

369H90064−7

0.3

DME

NARCO 001−4

369H90064−11

3.5

TRANSPONDER TR611B−28ATC

369H90064−81/−151

0.5

NAV RCVR RCA−AVN−211

REC

369H90066−503

0.2

TRANSCEIVER RCA−AVC−110 TRAN

369H90066−BSC

4.5

( 8 )

NAV/COM KING KX170A

REC

369H90071

1.0

TRANS

5.0

( 8 )

ADF KING

KR80

369H90064−9

0.4

KR85

369H90067

1.0

SSB SUNAIR ASB/125/60

REC

369H90144

2.5

TRANS

7.5

( 8 )

P.A. UNIVERSITY SOUND

IDLE

369H90146

0.1

PEAK

8.0

( 8 )

ICS INTERCOM

369H6426 ADP

369H90068

0.2

369H94008 ADP

369H90064

SYS.

0.2

INSTALLED OPTIONS AMPS

BASIC SHIP AMPS

2.8

9.3

8.3

44.4

34.4

66.5

56.5

TOTAL SHIP AMPERES

Page 19-6

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-2. Optional Equipment Electrical Load Analysis Chart (Cont)

HOVER

CRUISE

DAY

NIGHT

DAY

NIGHT

EQUIPMENT

PART

AVG. AMPS.

OPTIONS

DESIGNATION

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

ARMAMENT

GYRO

ATTITUDE

369H90041−501

0.7

DIRECTIONAL

369H90042−BSC

0.7

DIRECTIONAL

369H90042−501

1.8

ANTI−COL−LTS

(QTZ IODINE 2 LTS)

369H90062

1.5

BOOM (QTZ 1 LT)

369H90062−515

1.5

POS−LTS BOOM

369H90062−513

1.8

CARGO HOOK

369H90065

HOIST

( 13 )

369H90070

RE−IGNITION−ENGINE

369H90118−501/−505

EMERGENCY FLOATS

369H92557

2.2

HEATED PITOT TUBE

369H90034

1.3

HEATING − CABIN

369H90020

HEATING − ANTI−ICE

369H90020

VHF COMM (TRANS) RT−221AE−28

369H90064−3

VHF COMM (REC) RT−221BE−28

369H90064−5

1.1

VOR−VHF (NAV) RN−222AE−28

369H90064−7

0.3

DME

NARCO 001−4

369H90064−11

3.5

TRANSPONDER TR611B−28ATC

369H90064−81/−151

0.5

NAV RCVR RCA−AVN−211

REC

369H90066−503

0.2

TRANSCEIVER RCA−AVC−110 TRAN

369H90066−BSC

NAV/COM KING KX170A

REC

369H90071

1.0

TRANS

ADF KING

KR80

369H90064−9

0.4

KR85

369H90067

1.0

SSB SUNAIR ASB/125/60

REC

369H90144

2.5

TRANS

P.A. UNIVERSITY SOUND

IDLE

369H90146

0.1

PEAK

ICS INTERCOM

369H6426 ADP

369H90068

0.2

369H94008 ADP

369H90064

0.2

INSTALLED OPTIONS AMPS

BASIC SHIP AMPS

34.4

27.8

21.4

56.5

49.9

27.5

34.4

27.8

21.4

40.5

33.9

27.5

TOTAL SHIP AMPERES

Page 19-7

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-2. Optional Equipment Electrical Load Analysis Chart (Cont)

LANDING

EMERGENCY − GENERATOR OUT

DAY

NIGHT

DAY

NIGHT

EQUIPMENT

PART

AVG. AMPS.

OPTIONS

DESIGNATION

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

SEC.

MIN.

ARMAMENT

GYRO

ATTITUDE

369H90041−501

0.7

DIRECTIONAL

369H90042−BSC

0.7

DIRECTIONAL

369H90042−501

1.8

ANTI−COL−LTS

(QTZ IODINE 2 LTS)

369H90062

1.5

BOOM (QTZ 1 LT)

369H90062−515

1.5

POS−LTS BOOM

369H90062−513

1.8

CARGO HOOK

369H90065

HOIST

( 13 )

369H90070

RE−IGNITION−ENGINE

369H90118−501/−505

EMERGENCY FLOATS

369H92557

2.2

HEATED PITOT TUBE

369H90034

1.3

HEATING − CABIN

369H90020

HEATING − ANTI−ICE

369H90020

VHF COMM (TRANS) RT−221AE−28

369H90064−3

VHF COMM (REC) RT−221BE−28

369H90064−5

1.1

VOR−VHF (NAV) RN−222AE−28

369H90064−7

0.3

DME

NARCO 001−4

369H90064−11

3.5

TRANSPONDER TR611B−28ATC

369H90064−81/−151

0.5

NAV RCVR RCA−AVN−211

REC

369H90066−503

0.2

TRANSCEIVER RCA−AVC−110 TRAN

369H90066−BSC

NAV/COM KING KX170A

REC

369H90071

1.0

TRANS

ADF KING

KR80

369H90064−9

0.4

KR85

369H90067

1.0

SSB SUNAIR ASB/125/60

REC

369H90144

2.5

TRANS

P.A. UNIVERSITY SOUND

IDLE

369H90146

0.1

PEAK

ICS INTERCOM

369H6426 ADP

369H90068

0.2

369H94008 ADP

369H90064

0.2

INSTALLED OPTIONS AMPS

BASIC SHIP AMPS

4.4

26.5

− − −

4.1

26.2

10.2

TOTAL SHIP AMPERES

Page 19-8

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

BATTERY CHARGING GRAPH

FACTOR VS. TIME

3.0

ENGINE STARTING REQUIREMENTS DATA

2.5

2.0

1.5

1.0

0.5

TIME (SECONDS)

0.1

0.2

0.5

1.0

2.0

5.0

100

POSSIBLE SYSTEM PEAK, 369 AMPS

ELAPSED TIME IN MINUTES

PROBABLE SYSTEM PEAK, 360 AMPS

LIGHT OFF

TYPICAL CHARGING CURVE

FOR BATTERY

350

300

150

250

200

AT 75°F (24°C)

150

100

SEVERELY DISCHARGED BATTERY

TIME (SECONDS)

MODERATELY DISCHARGED BATTERY

STARTING TRANSIENT CURVE

TIME IN MINUTES

TO CIRCUIT BREAKERS AND LOADS

VOLTAGE

REGULATOR

STARTER

GENERATOR

REVERSE

CURRENT

RELAY

EXT. PWR.

BATTERY

−

28 V

BATTERY EXT. PWR.

SWITCH

30−188−1

Figure 19-2. Electrical System Load Analysis

Page 19-9

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE:

(1) The power source consists of:

A. Generator (369A4550) regulated at 26-28.5 Vdc (Ref. Generator Output table).

B. Battery (369A4530) (NI-CAD) 13 AH (19 CELL) Hi-Rate.

Generator Output

Operating

Speed

Amp Output

Volts

Altitude

Ambient Temp. Max.

Period

7500

26.0

Sea Level

Cont.

250°F (121°C)

8100

150

28.5

Sea Level

10 Min.

250°F (121°C)

8100

100

28.5

Sea Level

Cont.

160°F (71°C)

8300 - 12000

150

30.0

Sea Level

Cont.

104°F (40°C)

14000

Over−Speed

5 Min.

----

(2)

Ships with 369H4560 type console use a 4-Pack which includes an electrical engine oil pressure meter (6).

(3)

Manual controls replace electrical controls effective with production ships 0391HS, 0216HE and 0222HM.

(4)

Battery charging formula:

Avg. AMPS - (I) = AH X C;

I = Battery charging current;

AH = Ampere-hour capacity of battery, based on the 2-hour discharge rate;

C = Charging factor from the graph above.

(5)

This load is considered negligible.

(6)

This load is intermittent and is considered negligible.

(7)

Valves remain electrically energized after inflation of floats.

(8)

Duty cycle is 10% of maximum time interval.

(9)

Idle current 1 ampere maximum. average current 5-8 amperes, peak current 18 amperes.

(10)

Warning lights are operative during alarm conditions only.

(11)

Solenoid valves remain energized during time floats are inflated.

(12)

See starting load chart.

(13)

The maximum duty cycle for the hoist is 3 complete cycles (approximately 15 minutes total) and then rest

40 minutes before repeating cycle.

(14)

Ships with 369H4260 type console have one light only for engine oil pressure and temperature.

(15)

Ships with 369H4260 type console have one light only for engine oil, main rotor and tail rotor chip

detectors.

(16)

Time interval of 15 minutes or over is considered as continuous.

(17)

Instrument and panel lights are included with dimmer system.

(18)

For longer duration, see typical charging curve. Accumulate time for different operating conditions.

Page 19-10

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-3. Troubleshooting Dc Power Distribution

Symptom

Probable Trouble

Corrective Action

WARNING: Before removing or installing components of the electrical systems, check that all electrical

power is OFF. If units are not immediately replaced, ensure that all electrical connectors are suitably

capped and stowed and all loose cable ends are properly insulated and stowed to prevent the

possibility of shorting. Serious injury or death could result from voltages present in the electrical

system.

Battery fails to energize electrical

Defective power selector switch

Replace switch.

circuits

Defective battery relay

Replace battery relay.

Battery discharged

Install serviceable battery.

Discharged battery

Charging rate incorrectly set

Adjust voltage regulator.

Battery idle too long

Install serviceable battery.

Excessive corrosion on battery

Exposure to water or corrosive fluids

Clean terminals, coat with

terminal

non-corrosive grease.

Battery overheats and/or

Charging rate too high

Adjust voltage regulator.

discharges smoke

Loose battery terminal links, straps

Repair battery as necessary.

or screws

Damaged or defective battery

Repair or replace battery.

Starter/generator fails to function

Circuit breaker out

Reset circuit breaker.

when START switch pressed

Start relay defective

Replace start relay.

Battery relay defective

Replace battery relay.

APU relay defective

Replace APU relay.

Discharged battery

Install serviceable battery.

APU, reverse polarity diode open

Replace diode.

Start/generator defective

Replace starter/generator.

START switch or wiring defective

Replace switch or repair defective

wiring.

Page 19-11

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-3. Troubleshooting Dc Power Distribution (Cont.)

Symptom

Probable Trouble

Corrective Action

Starter/generator fails to supply

Circuit breaker out

Reset circuit breaker.

charging current with engine

Reverse current relay defective

Replace reverse current relay.

operating

Starter/generator defective (Check

Replace sheared drive shaft.

for sheared armature drive shaft

through air inlet screen)

Voltage regulator defective

Replace voltage regulator.

Voltage regulator incorrectly adjusted

Adjust voltage regulator.

Overvoltage relay defective

Replace overvoltage relay.

GEN-OFF switch defective

Replace switch.

Defective wiring

Repair or replace defective wiring.

Ammeter indication off-scale below

Defective reverse current relay

Replace reverse current relay.

zero; engine not operating and

GEN-OFF switch is on

GEN OUT indicator light on;

Weak generator field

Replace starter/generator.

voltage lower than normal when

Defective voltage regulator

Replace voltage regulator.

engine operating

Defective starter/generator

Replace or repair starter/generator.

Incorrectly adjusted voltage regulator

Adjust voltage regulator.

Fluctuating current indication on

Unstable voltage regulator

Replace voltage regulator.

ammeter

Brushes excessively worn

Replace starter/generator brushes.

Defective starter/generator

Replace or repair starter/generator.

Loose ammeter circuit wiring or

Check ammeter circuit connections

defective resistor R3

and resister R3. Repair as

necessary.

Excessively high or low current

Incorrectly adjusted voltage regulator

Adjust voltage regulator.

indication on ammeter, engine

Defective voltage regulator

Replace voltage regulator.

operating; GEN OUT indicator light

not on

Defective starter/generator

Replace or repair starter/generator.

Defective ammeter

Replace instrument cluster (three

pack).

Incorrect connection of ammeter

Check shunt wire connection and

shunt wire, or defective resistor R3

resistor R3. Repair as necessary.

Adjustment of voltage regulator has

Defective voltage regulator

Replace voltage regulator.

no effect on voltage indication

Page 19-12

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

4. Wiring Harnesses

NOTE: Observe method of wiring harness rout−

ing, clamping and tying prior to removal to

Components of the electrical system are

facilitate reinstallation.

connected by wiring harnesses, with wire

identification as shown in the applicable

(7).

Cut tying twine and cut or loosen nylon

wiring diagrams.

straps as necessary to permit removal

of harness.

Wires in a harness are terminated with

(8).

Route replacement harness into

terminal lugs, electrical connectors (plugs and

position.

receptacles), Wire Mate locking type pin

connectors, knife splices or snap−in contacts.

(9).

Install harness connectors (receptacle,

plug or inserts).

Wiring harnesses are held in place by nylon

self−clinching loop straps and nylon tying

(10).

Connect any harness single−terminal

twine. Nylon caterpillar−type grommets

leads.

provide insulation where harnesses pass

(11).

Replace tying twine (30, Table 2−4) and

through structural openings.

reinstall nylon straps, if available.

(Substitute tying twine if nylon straps

Each electrical wire of a harness is identified

unavailable.)

by a letter−number code (with the exception of

a few color−coded lengths that are integral to a

(12).

Install component(s) removed to gain

specific component or assembly). The letter−

access.

number code identifies the function of the

circuit of which the wire is a part, the wire

(13).

Close panels and reinstall fasteners.

number, segment and wire size (gage),

(14).

Install access door, where removed.

respectively. A description of the wire code is

included in Section 20.

(15).

Connect battery and external power

source.

NOTE: Electrical wiring that interconnects the

optional integrated interphone control unit

(16).

Check operation of all circuits affected

and terminal blocks for the optional inter−

by harness replacement. (Refer to

phone control system is installed in all heli−

applicable wiring diagrams.)

copters on which the electrical system is

5. Electrical Connectors

standard.

Plugs, receptacles, terminal block snap−in type

A. Wire Harness Replacement

contacts, locking type pin connectors, knife

splices and terminal lugs provide the means by

(1). Check that all electrical power is OFF.

which wiring and electrical harness assemblies

Accomplish the following steps as

are connected to individual panels and

applicable.

electrical components.

(2). Remove access doors.

Each plug−receptacle combination is secured

with lockwire or otherwise mechanically

(3). Open panel by removing the fasteners

locked, to prevent opening of the connection

that secure panel to structural support.

due to vibration.

(4). Remove component(s) blocking access.

Terminal block snap−in type contacts physical−

(Refer to component coverage in

ly and electrically connect individual harness

appropriate section of HMI.)

leads (wires) to terminal block modules.

(5). Disconnect and tag−identify wire

A. Plug/Socket Connector Repair or

terminal(s) at applicable panel.

Replacement

(6). Disconnect wiring harness connectors

(Ref. Figure 19−3)

(plugs or receptacles), Wire Mate

(1). Check that all electrical power is OFF.

connections and/or knife splices and

tag−identify any single terminal

(2). Remove any connector bonding or

connections

lockwire.

Page 19-13

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

MOUNTING PLATE

LEVER

(BULKHEAD INSTL)

PIVOT

LOCK TAB

FEMALE INSERT

NOTE 2

FIXED JACKSCREW

(NOTE 1)

NOTE 2

HOOD

FIXED JACKSCREW

EXPLODED VIEW

(NOTE 1)

OF RECEPTACLE

SELF−LOCKING

MALE INSERT

NOTE 2

JACKSCREW AND

JACKSCREW KNOBS

MALE INSERT

NOTE 2

FACE GASKET

ASSEMBLED VIEW OF MATING

(TYP) (NOTE 4)

SELF−LOCKING

CONNECTOR HALF WITH

HOOD AND TURNABLE LONG

JACKSCREWS WITH KNOBS

HOOD

EXPLODED VIEW OF PLUG

NOTE 3

REMOVABLE CONTACT

REMOVAL TOOL

(107R1001)

ASSEMBLIES

NOTES:

PLUG OR RECEPTACLE INSERTS WITH 26 OR FEWER CONTACTS

ARE ASSEMBLED WITH, AND HELD IN HOOD, OR IN MOUNTING PLATE

CROSS−SECTION VIEW

BY ONLY THE TURNABLE OR FIXED JACKSCREW AND JACKSOCKET.

OF CONNECTOR

MACHINE SCREWS (4−40 OR 6−32 UNC THREAD SERIES) ARE USED TO

ASSEMBLE PLUG OR RECEPTACLE INSERTS HAVING 34 OR MORE

CONTACTS.

REMOVABLE CONTACTS INSTALLED ON WIRES WITH HAND−OPERATED

CRIMPING TOOL.

NOT INSTALLED ON ALL CONNECTORS.

30−101B

Figure 19-3. Repair or Replacement of Rectangular Electrical Connectors

Page 19-14

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). Disconnect electrical connector from

B. Disconnection/Connection of Wire Mate

mating plug or receptacle by using the

Connectors

applicable following steps:

Wire Mate locking type pin con−

CAUTION

nectors will be damaged if

(a). Loosen strain−relief clamp on

pulled apart and disconnected without use

connector hood or adapter.

of appropriateconnector insertion/extrac−

tion tool.

(b). On circular type connectors, loosen

hood and disengage plug lock spring

(1). Disconnect Wire Mate pin connectors as

from receptacle lock ring by rotating

follows:

lock spring in either direction.

(a). Slide white end of insertion/extrac−

tion tool (42 or 43, Table 2−2) on wire

(c). Disassemble shell or hood from

with tip end toward male contact

electrical connector to expose termi−

terminal.

nals.

(b). While holding connector female half,

(d). Disconnect crimp−type removable

slide tool along wire and fully insert

contacts by using the appropriate

tool around male contact terminal

contact removal tool (33 or 36,

into female half. This disengages

Table 2−2).

retaining clip tines from male contact

terminal shoulder.

(4).

Slide insulation sleeves back over wires

and unsolder wires from contact

(c). Pull wire and male contact from

inserts, or cut off crimp−type contacts

female half while holding tool in

place.

as necessary.

(2). Connect Wire Mate pin connectors as

(5).

Solder or crimp electrical wires to insert

follows:

contacts and remove identifying tags, if

used. Use a tin−alloy solder (48,

(a). Slide colored end of insertion/extrac−

Table 2−4) for all soldering operations,

tion tool (42 or 43) on wire with tip

and the appropriate crimping tool (34 or

end behind male contact terminal

35, Table 2−2) for replacement of

shoulder.

removable crimp−type contacts.

(b). Insert and push male contact termi−

nal straight into connector female

(6).

Install crimp−type contacts by using

half, using tool end. A click will occur

the appropriate contact insertion tool

when contact terminal seats and

(33 or 36).

retaining clip tines snap in place

behind terminal shoulder.

(7).

Check for short circuits. Ensure that

resistance between pins is infinite

(c). Remove insertion−extraction tool and

except where pins are interconnected.

gently pull on connected wires to

(Refer to applicable wiring diagrams.)

ensure firm seating.

C. Minilok and Modulok Terminal Block

(8).

Join connector halves and secure.

Contact Tip Replacement

(a). On circular type connectors, rotate

(Ref. Figure 19−4)

plug lock spring to engage receptacle

lock ring.

(1). Check that all electrical power is OFF.

(2). Use a Burndy insertion/extraction tool

(b). Tighten hood or adapter strain−relief

(33, Table 2−2) to pull a HYTIP contact

clamp on connector and tighten

from a MINILOK module.

clamp screws.

(3). Strip either 0.17 or 0.20 inch (4.37 or

(c). Use lockwire and attach connector

5.16 mm) of insulation from end of wire,

bonding, as applicable.

as applicable.

Page 19-15

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SIDE FEED MODULE TYPE AMM 20−1

TRACK TYPE AMM 3600T−1 (POLYVINYL CHLORIDE)

TOP FEED MODULE TYPE AMM 20T−1

NOTE

BURNDY

MINILOK

SIDE FEED

MODULE

BUSSING

(TYP)

BUSSING

(TYP)

TOP FEED

MODULE

SCREW

A6SMM20T−1

(ALL RECEPTACLES BUSSED)

UPPER HALF

A4SMM20−1

A22DMM20−1

A23DMM20T−1

(ALL TIERS

(TWO TOP TIERS BUSSED)

(TWO SETS OF THREE

BUSSED)

(TWO BOTTOM TIERS BUSSED)

MINILOK

BASE

RECEPTACLES BUSSED)

A32DMM20T−1

(THREE SETS OF TWO

A4DMM20−1

11/64 IN.

RECEPTACLES BUSSED)

(ALL TIERS

(4.3656 MM)

INSPECTION

INDIVIDUAL)

HOLE

PCM 22M−HIF3 (AWG 24−22) USE HYTOOL M8ND WITH DIE SET N22PCT−1

MINILOK

PCM 22M−HIF3 (AWG 20) USE HYTOOL M8ND WITH DIE SET N22PCT−2

HYTIP

TYPICAL INSTALLATION OF MINILOK TERMINAL BLOCK MODULES

(REF. TB1, TB5, TB7 AND TB502)

13/64 IN.

TRACK, AM0750T−1 (NOTE) (CADMIUM−PLATE STEEL)

(5.1594 MM)

TRACK

HEADLESS

2 TIER MODULE

MODULOK CONTACT TIP

SETSCREW

AYH 14−H (AWG 20−14)

4 TIER MODULE

USE HYTOOL M8ND

WITH DIE SET N14HCT

AMC−1 CLAMP

NOTE: THE FOUR MIDDLE NUMERICAL

DIGITS IDENTIFY LENGTH IN INCHES.

AMM TRACK COMES IN 36 IN. (914.4 MM)

BUSSING

LENGTHS AND IS CUT TO SIZE: AM

(TYP)

TRACK CAN BE ORDERED IN ANY

A2SM14−1

PRECUT LENGTH UP TO 32 IN. (812.8

MM) (EG. 0750 = 7.50 IN. (190.5 MM).

A2DM14−1

A22DM14−1

A4DM14−1

A4SM14−1

TYPICAL INSTALLATION OF MODULOK TERMINAL BLOCK MODULES

(REF. TB3)

30−102A

Figure 19-4. Identification and Replacement of Burndy Terminal Block Modules

Page 19-16

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(4).

MODULOK modules have either

NOTE: To facilitate reassembly, tag and identi−

two−tier or four−tier spring−loaded

fy all wires that are to be disconnectedfrom

connectors. Using a standard screw−

terminal block module to be replaced.

driver for recessed head screws, twist

the locking screw counterclockwise to

(2).

Remove contact tips (Ref. Minilok and

the quick−disconnect position of the

Modulok Terminal Block Contact Tip

Screw and spring mechanism to release

Replacement).

the contact tips. Pull tips from spring−

loaded socket connectors.

(3).

Loosen the screw that secures the end

clamp holding the modules on the

(5).

Insert stripped end of wire into snap−in

track. Slide the end clamp away from

contact. On HYTIP (MINILOK)

the modules and separate the module to

contacts, check that stripped end of

be replaced by unsnapping it from

wire extends past the inspection hole.

adjoining modules.

Make sure the stripped end of the wire

is inserted as far as possible into the

(4).

With modules separated for clearance

contact tip and that the wire insulation

from one another, remove the module

extends approximately one−sixteenth of

by turning it 90 degrees and unsnap−

an inch into the contact shoulder

ping it from the track.

(MINILOK) or to end of the contact

shoulder notch (MODULOK).

(5).

Insert the replacement module into

mounting position between or next to

(6).

Using the Burndy manual crimping tool

the correct adjoining modules, rotate it

and correct die−set (34, Table 2−2),

90 degrees and snap into place. Press

crimp contact on the wire.

modules together.

(7).

Visually inspect contact tip on the wire;

(6).

Slide the end clamp into place against

check that it is firmly attached to the

the outside module. While pressing and

wire and that the stripped end of the

holding the clamp against the outside

wire blocks inspection hole in HYTIP

module, tighten the end clamp screw.

contacts.

(7).

Install contact tips.

(8).

Use a Burndy insertion/extraction tool

(33) to push HYTIP snap−in contact

(8).

Remove identifying tags from wires.

into the proper terminal block module

of the terminal block assembly. (Refer

E. Electrical Bonding Connector

to applicable wiring diagrams.)

Maintenance

(9).

Plug MODULOK contact tips into

(Ref. Figure 19−5)

spring−loaded socket connectors and

twist locking screw clockwise to the

(1). When replacing a bonding jumper, use

locked position (spring fully com−

solvent (1, Table 2−4) to remove all

pressed).

traces of grease, oil or other nonconduc−

NOTE: MODULOK modules may be set in ei−

tive film from the mating surfaces.

ther the quick− disconnect position or the

Nonsoluble films should be removed by

locked position; the spring− loaded socket

sanding and polishing with grade 400

connectors exert uniform pressure in either

abrasive paper (20), using care to

position. The quick− disconnect position

remove only a minimum of the base

should only be used to facilitate circuit ring−

metal. The polished area should be

out.

brushed clean.

D. Minilok and Modulok Terminal Block

(2). After polishing aluminum alloys, apply

Replacement

a brush coating of Iridite No. 14−2,

Class 3, chemical film protection (8) to

(1). Check that all electrical power is OFF.

the mating surfaces.

Page 19-17

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

CADMIUM−PLATED OR

CRES SCREW OR BOLT

STEEL SPRING

ALUMINUM OR MAGNESIUM

LOCKWASHER

STRUCTURE

CADMIUM−PLATED

OR CRES WASHER

JUMPER

(LIGHT SERIES)

AL ALY WASHER ( # )

AL ALY WASHER

(LIGHT SERIES)

SCREW/BOLT CONNECTION (TYP)

STANDARD OR LOW HEIGHT

STEEL LOCKNUT

AL ALY OR MAGNESIUM STRUCTURE

STEP 3

STEPS 1 AND 2

CADMIUM−PLATED OR

CADMIUM−PLATED OR CRES PLAIN HEX NUT

CRES SCREW OR BOLT

CLEANING, CORROSION

AL ALY WASHER (LIGHT SERIES)

PROTECTION AND FINISHING

STANDARD OR LOW HEIGHT

STEEL LOCKNUT

STUD CONNECTION (TYP)

AL ALY WASHER

(LIGHT SERIES)

JUMPER

STEPS 1 AND 2

STEEL SPRING

STEP 3

LOCKWASHER

BONDING JUMPER TO STRUCTURE ( * )

CADMIUM−PLATED OR CRES SHORT

THREAD SCREW OR BOLT

CLAMP ( * * )

CADMIUM−PLATED OR

CRES WASHERS

STANDARD OR THIN LOCKNUT

BONDING JUMPER TO TUBE ( * )

STEP 1. CLEAN TO BASE METAL: AREA 1−1/2 DIA. OF

( # )

NOT USED ON PLATED OR CRES STRUCTURE.

WASHER; AREA 1−1/2 CLAMP WIDTH AND INSIDE

( * )

USE CADMIUM−PLATED PARTS BELOW 300°F (149°C)

SURFACE OF CLAMP. (CLEAN CLAMP

USE CRES PARTS ABOVE 300°F (149°C); USE

EAR−TO−TERMINAL MATING SURFACE.)

WASHERS AGAINST STRUCTURE AS APPLICABLE TO

STEP 2. BRUSH COAT THE CLEANED AREA OF ALUMINUM

THE STRUCTURE MATERIAL.

WITH CHEMICAL FILM (8, TABLE 2−4).

( * * )

ALCLAD CLAMP FOR PLATED STEEL, AL ALY FOR MAG

STEP 3. APPLY CLEAR LACQUER (47) TO 1−1/2 DIA. OF

ALY STRUCTURE. CADMIUM−PLATED STEEL CLAMP

CLEANED AREA.

FOR NON−PLATED STEEL STRUCTURE (CRES CLAMPS

FOR CRES TUBE).

30−103A

Figure 19-5. Typical Requirement for Electrical Bonding Connections

Page 19-18

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). When removed bonding jumpers are

A voltage regulator, overvoltage relay and

reconnected, check that the clear

reverse current relay function with the

lacquer finish, originally applied to the

starter/generator to monitor, regulate and

cleaned mating surfaces, will not act as

control generator dc output voltage, the

an insulator between the mating

nominal 28 Vdc voltage for the electrical

surfaces. Restore mating surfaces to the

system, charging of the battery and protect

cleaned condition, as necessary,

from overvoltage. The starter/generator both

according to steps (1). and (2). above.

starts the engine and generates dc electrical

power.

(4). After connecting a bonding jumper,

apply clear lacquer (47) to the exposed

Battery temperature sensing equipment

area of the cleaned surface.

monitors and provides a visual indication of

excessive battery temperature.

(5). Ensure that bonding jumpers do not

Voltage reduction and calibration resistors are

impede the operation of movable

used for certain instruments and associated

components.

equipment.

F. External Power Receptacle Replacement

Miscellaneous switches provide for application

(Ref. Figure 19−6)

of dc power and control of related equipment.

The night lighting system is part of the

(1). Check that all electrical power is OFF.

electrical system on a helicopter with instru−

(2). Remove the two attaching screws and

ment panel type B. Information is provided in

pull receptacle outward.

Section 17 on electrically actuated instru−

ments, caution and warning indicator lights,

NOTE: It may be necessary to disconnect the

engine power out warning equipment, the

ground cable to gain sufficient slack for re−

associated sending units, and the other

ceptacle removal. If so, open right access

components installed directly in the instru−

door of pilot’s compartment floor for access

ment panel, excluding the control switches and

to cabling.

circuit breakers.

(3). Disconnect cables and remove recep−

Refer to system coverage for information on

tacle.

the engine starting pump (Section 12), the N2

trim actuator (Section 11), and cyclic trim

(4). Attach cables to terminals of replace−

actuators (Section 7). Maintenance data for

ment receptacle and secure with

optional electrical equipment items such as

terminal nuts.

night lighting kit on a helicopter with instru−

NOTE: The aft terminal is the negative (−) or

ment panel type A, heated pitot tube, inter−

ground terminal, the center terminal is the

communication systems, etc., can be found in

positive (+) terminal, and the forward(small

CSP−H−3, HMI Appendix A.

polarity pin) terminal is not used.

7. Voltage Regulator

(5). Install receptacle with two screws.

(Ref. Figure 19−6) The static voltage regulator

maintains a constant generator output voltage

(6). Reconnect any cabling disconnected to

under varying speed and load conditions. The

obtain slack for receptacle removal.

regulator has a voltage adjustment range of

26−30 volts and contains an overvoltage

6. Electrical Equipment

circuit.

Electrical equipment consists of the basic

A. Voltage Regulator Replacement

power supply, distribution and control compo−

nents, and other electrical items installed as

(1). Check that all electrical power is OFF.

standard equipment, in all configurations of

(2). Open pilot’s compartment floor left

the 500 Series helicopter.

access door, disconnect electrical

Such equipment includes the battery, starter/

connector, remove four mounting

generator, control switches, circuit breakers

screws and washers, and lift out voltage

and power supply and control relays.

regulator.

Page 19-19

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

MINILOK MODULE

TERMINAL BLOCK

PILOT’S COMPARTMENT FLOOR

(TB7)

VOLTAGE

REGULATOR

RESISTOR BOARD

UTILITY RECEPTACLE (J103)

(TB8) (R1, R2)

RESISTOR BOARD (R9)

(NOTE 2)

R10

ARMAMENT RECEPTACLE (J200)

R11

R12

BATTERY

EXTERNAL RECEPTACLE (J100)

( − ) NEGATIVE

MODULOK

TERMINAL PIN

(TYP) (2 PLCS)

TERMINAL

BLOCK (TB3)

POLARITY PIN

MINILOK MODULE

(NOT USED)

TERMINAL BLOCK

(TB1)

( + ) POSITIVE

TERMINAL PIN

MINILOK MODULE

FWD

TERMINAL BLOCK

(TB5)

HEAT DUCT AND

VNE CARD COVER

CABIN HEAT SWITCH

(OPTIONAL)

SIDE−MOUNTED

SWITCH

FACE−MOUNTED

SWITCH

SPACER

ENG. DE−ICE

SWITCH

(NOTE 1)

HEAT DUCT AND

BEZEL

VNE CARD COVER

NOTES:

SWITCH INSTALLED AT RIGHT SIDE OF COVER WHEN PILOT

SEAT AT RIGHT POSITION.

FWD AND AFT CIGAR LIGHTER RESISTOR INSTALLATION

SHOWN, USED WITH INSTRUMENT PANEL TYPE A.

30−104E

Figure 19-6. Electrical Equipment (Cabin Locations)

Page 19-20

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). Install replacement voltage regulator

Table 19-4. Recommended Voltage Setting

with four screws and washers, and

Battery Ambient Temperature

attach electrical connector.

in Degrees

F (C)

Voltage Setting

(4). Perform an operational check of the

Up to 80 (26.9)

28. 5

new regulator and make adjustment, as

necessary.

81 - 100

(27.4

- 38.1)

28.O

101 - 130

(38.6

- 54.9)

27. 5

B. Installed Voltage Regulator Adjustment

131 - 140

(55.5

- 60.5)

27.0

NOTE: Figures in Voltage Setting column

(Ref. Table 19−4) The voltage regulator is to be

represent recommended constant potential

adjusted for a specific generator output voltage

charging voltages to which voltage regulator

according to prevailing ambient temperature.

is to be adjusted for listed temperatures.

(1). Connect a precision voltmeter to the

voltage regulator test jacks (Ref.

(4).

Increase N_l rpm to 68−70% and check

Figure 19−7).

voltmeter reading. If reading is not as

shown in Table 19−4, open the adjust−

NOTE: The voltmeter must be capable of mea−

ment screw cover, and on the connector

suring voltage within 0.25% full scale accu−

end of the voltage regulator, insert a

racy in the 0−50 Vdc range. A Weston Model

small screwdriver, and turn adjustment

931, or equivalent, is recommended. Com−

screw slowly for incremental voltage

monly available multimeters have a much

increase or decrease as necessary.

broader accuracy tolerance and are there−

Increments of 0.5 volt are possible.

fore unsatisfactory for use in setting the

(5).

While maintaining full down collective

voltage regulator.

pitch, increase N_l rpm to approximately

77−80 percent.

(2). Start engine, keep collective pitch full

(6).

Check voltmeter to see if voltage

down and allow N_l idle speed to

stabilize.

remains within the applicable tolerance

range. If necessary, readjust voltage to

remain within limits at engine speeds

(3). Turn off all unnecessary electrical

specified in steps (4). and (5). above.

loads.

(7).

Rapidly increase electrical loads by

turning on all radio and electrical

equipment possible. Except for momen−

tary fluctuations, the regulator must

maintain generator output at voltage

listed in Table 19−4 as indicated on

meter. If the electrical loads cause

voltage to vary outside this range,

replace voltage regulator and repeat

VOLTAGE

TEST JACKS

steps (1).thru (6).

(8).

Turn off electrical loads, reduce N_l rpm

CONNECTOR

to 68−70 percent, and repeat step (7).

Replace regulator if voltage setting

varies from that specified for an

ADJUSTMENT

SCREW COVER

increase in electrical load.

VOLTAGE ADJUSTMENT

SCREW

(9).

Shut down engine.

30−105

(10).

Disconnect and remove voltmeter, close

Figure 19-7. Voltage Regulator Test Points

voltage regulator adjustment screw

Page 19-21

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

cover, and tighten cover retaining

This should occur at 32.0 ±1.0 volts

screw.

indicated on meter M1. Return poten−

tiometer to full CCW position.

C. Voltage Regulator Bench Testing

(11). Reset the overvoltage relay by switch−

(Ref. Figure 19−8 for test equipment and

ing Sl OFF and then ON.

wiring hookup)

(12). Turn switches OFF in the following

(1).

Mount generator on vari−drive.

order: S1, S3, S5, and S4, Disconnect

the voltage regulator.

(2).

Connect voltage regulator into test

circuit.

8. Overvoltage Relay

(3).

Adjust potentiometer R2 fully CCW

(Ref. Figure 19−9) The overvoltage relay

while the load bank is off (switch S5

protects the 28 Vdc system from an overvol−

OFF). Set switch Sl OFF and S3 and S4

tage condition. With the GEN OFF switch on,

ON.

the normally closed contacts of the overvoltage

relay apply generator output to the SW

(4).

Hold momentary contact switch S2 ON,

(switch) circuit of the reverse current relay.

start vari−drive and adjust to bring

When an overvoltage occurs in the range of

generator speed to 7200 rpm or above.

32.0 ±1.0 volts, the overvoltage relay ener−

Voltage shown on meter M1 must not

gizes, removing power from the switch circuit

exceed 10.75 volts; this indicates that

of the reverse current relay to remove genera−

the voltage regulator is in the simu−

tor output from the electrical system.

lated start mode.

No attempt should be made to

CAUTION

(5).

Release switch S2. Regulator must

adjust the overvoltage circuit in

regulate voltage to between 26.0−30.0

the helicopter. Adjustment is performed

Vdc as indicated on meter M1.

only during bench test of the voltage regula−

tor.

(6).

Check that full range of voltage

A. Overvoltage Relay Replacement

adjustment potentiometer on voltage

regulator is 26.0−30.0 Vdc as indicated

(1).

Check that all electrical power is OFF.

on meter M1.

(2).

Gain access to overvoltage relay on

(7).

Adjust generator speed to 10,750 rpm.

instrument panel structure by remov−

Switch Sl ON and adjust the potentiom−

ing fairing from left side of instrument

eter on the voltage regulator to 28.5

panel.

±0.3 Vdc as indicated on meter M1.

(3).

Remove two screws, washers, and nuts

(8).

Switch S5 ON and adjust the load bank

that attach relay.

to a 100−ampere load as indicated on

meter M2; then switch S1 ON and then

(4).

Unsolder electrical wiring from relay

OFF. The voltage regulator shall

terminal lugs.

regulate voltage under load surge

conditions.

(5).

Be sure insulation sleeving is used over

wires and solder wires to terminal lugs

(9).

Decrease generator speed to 7200 rpm

of replacement relay. Slide insulation

and apply a 100−ampere load; then

sleeving over relay solder terminals.

switch Sl ON and OFF. The voltage

Remove identifying tags if used.

regulator shall regulate voltage under

load surge conditions.

(6).

Locate overvoltage relay on mounting

panel and secure with screws, washers

(10).

Adjust load bank to 10−20 ampere load.

and nuts.

Switch S4 OFF. Adjust potentiometer

R2 CW until overvoltage relay operates.

(7).

Reinstall instrument panel fairing.

Page 19-22

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

0−50 VDC

VOLTMETER

RHEOSTAT R2

CONNECTOR

25 OHMS, 1000 W

MS3106E14S−6S

E−

VOLTAGE

REGULATOR

(UNDER TEST)

A+

B+

GEN

E D F

FUSE

0−200 A

50 MV.

A AMMETER

200A

SHUNT

SWITCH

S3 SPST

R1, 1W, 5%

120 OHMS

RESISTOR

BATTERY

SWITCH

GENERATOR

BATTERY

24 VDC

S4 SPST

S1 SPST

TERMINAL

SWITCH

−

SWITCH

TERMINAL

LOAD

BANK

TERMINAL

S2 SPST

MOMENTARY SWITCH

REVERSE CURRENT RELAY

OVERVOLTAGE RELAY

ITEM

EQUIPMENT DESCRIPTION

NO.

VARI−DRIVE, 3,000−12,000 RPM (U.S. TYPE VEU−GSTD OR

EQUIVALENT).

DC GENERATOR, 28 VOLT (369A4550 OR EQUIVALENT).

NI−CAD BATTERY, 24 VOLT (369A4530 OR EQUIVALENT).

0−200A DC AMMETER (M2), 50 MV FULL SCALE (WESTON MODEL

931 WITH 50 MV, 200 AMPERE SHUNT, OR EQUIVALENT).

0−50 VDC VOLTMETER (M1), CALIBRATED WITHIN 0.25%, AT

0−50 VOLTS (WESTON MODEL 931 OR EQUIVALENT).

LOAD BANK, 0−150 AMPERES (SUN ELECTRIC COMPANY MODEL

GBL OR EQUIVALENT).

OVERVOLTAGE RELAY (369A4557 OR EQUIVALENT).

REVERSE CURRENT RELAY (HARTMANN A700XA OR EQUIVALENT).

SWITCHES AND WIRING AS REQUIRED.

30−106C

Figure 19-8. Test Hookup for Voltage Regulator

Page 19-23

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

UPPER INSTRUMENT PANEL

SUPPORT ASSEMBLY

R303 OIL PRESSURE

GAUGE ADJUSTMENT

(NOTE 3)

MINILOK MODULE

ASSY (TB502)

TERMINAL BLOCK (TB501)

RUBBER INSULATOR

COVER

KEY SWITCH

(NOTE 1)

OVERVOLTAGE RELAY (K103)

(NOTE 2)

ENGINE POWER OUT WARNING UNIT

AUDIO AMPLIFIER

INDICATOR LIGHTS DIMMER ASSY

TERMINAL BLOCK (TB6)

LOWER INSTRUMENT PANEL

SUPPORT ASSY

NOTES:

WHEN REPLACING KEY SWITCH, USE AN3066−6 NUT

AND SHAKEPROOF WASHER IN PLACE OF NUT SUPPLIED

WITH KEY SWITCH.

COVER RELAY SOLDER TERMINALS WITH ELECTRICAL

INSULATION SLEEVING (31, TABLE 2−4).

PART OF CURRENT CONFIGURATION OIL PRESSURE

GAUGE CIRCUIT.

30−107C

Figure 19-9. Electrical Equipment Locations (Instrument Panel Type A)

Page 19-24

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

POST LIGHT

WIRE SPLICES

LIGHT AND

HORN HOUSING

(NOTE 1)

TB104

POST LIGHT

INSTRUMENT PANEL

TB105

CAUTION AND

(TYP) (NOTE 2)

STRUCTURE

WARNING LIGHT

(TYP) (NOTE 1)

HOOD

INDICATING LIGHTS

DIMMER DS11

(NOTE 1)

TB106

(NOTE 4)

EPO WARNING

UNIT DS10

TB501

(NOTE 1)

TB502

LOWER SWITCH AND

CIRCUIT BREAKER

PANEL

OVERVOLTAGE

RELAY K103

OVERVOLTAGE

RELAY K103

(NOTE 3)

TB101

J11

TB6

J10

CIGAR

R10

LIGHTER

R11

RESISTORS

R12

ACCESS PANEL

RELAY MOUNTING

PROVISIONS (TYP)

PEDISTAL

STRUCTURE

NOTES:

REFER TO SECTION 17.

REFER TO CSP−H−3.

EARLY CONFIGURATION ONLY.

NOT ON CURRENT CONFIGURATION.

30−186B

Figure 19-10. Electrical Equipment Locations (Instrument Panel Type B)

Page 19-25

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

9. Circuit Breaker Panel

corner of the instrument panel in the basic

configuration. Mounting holes for four optional

(Ref. Figure 19−1) The circuit breaker panel,

equipment control switches are also provided

located on the lower right side of the instru−

at this panel location. The basic control

ment panel, is a removable assembly with

switches are one key type, two circuit breaker

provisions for mounting 14 pushbutton−type

type, one pushbutton type, and two toggle

circuit breakers; 7 breakers are used in the

type.

basic configuration.

Control functions are apparent from adjacent

The circuit breakers are normally depressed

legends; the UTILITY and START PUMP

(button in) when the associated circuits are

switches are the circuit breaker type that will

energized.

snap to the off position if the circuit is over−

loaded. The switch marked UTILITY controls

When a circuit is overloaded, the circuit

power to the two−wire receptacle at the lower

breaker button pops out and de−energizes the

left corner of the forward canted bulkhead

circuit.

(Ref. Figure 19−6).

A. Circuit Breaker Replacement

A. Control Switch Replacement

(1). Check that all electrical power is OFF.

If the main power selector

CAUTION

(2). Remove the three screws that attach

switch is to be replaced, be sure

circuit breaker panel to instrument

to disconnect the battery and external pow−

panel. Pull panel out to expose wiring

er.

to circuit breakers.

NOTE:

When key switch (Ref. Figure 19−9) is

NOTE: Check the orientation of installed cir−

replaced, an AN3066− 6 nut and a shake−

cuit breakers. Observe that each column of

proof washer are to be used in place of nut

breakers has a staggered installation; one

supplied with replacement switch.

horizontal, then one vertical. This orienta−

(1). Check that all electrical power is OFF.

tion is required for installation clearance be−

tween breakers and should be maintained.

(2). Remove the two rectangular blank

panels and left side fairing from the

(3). Disconnect wiring from circuit breaker

instrument panel to gain access to the

to be replaced; then remove hex nut and

switch to be replaced (Section 17).

breaker.

(3). Remove hex nut or screws and washers

(4). Remove and discard the key washer

as applicable; then remove switch far

supplied with a new circuit breaker.

enough to permit the wiring to be

(5). Position the replacement breaker for

disconnected from the switch.

correct orientation and secure with hex

nut. Reconnect wiring and reinstall the

(4). Position replacement switch and

circuit breaker panel.

reconnect wiring; install attaching

hardware.

(6). Check operation of the new circuit

breaker.

(5). Check operation of the new control

switch.

10. Control Switches

(6). Reinstall the left side fairing and blank

(Ref. Figure 19−1) Six individually removable

panels on the instrument panel (Section

control switches are installed in the lower left

17).

Page 19-26

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 19-5. Resistor Reference Designator

Circuit

Purpose

Location

Instrument cluster power

R1 (reduce voltage)

Part of TB8 terminal board mounted

supply

on structure beneath pilot’s

compartment floor, left side

(Figure 19-6).

Voltage regulator/overvoltage

R2 (calibrate sensing circuit sensitivity Same as R1 (mounted on TB 8,

relay sensing circuit

for correct tripping of overvoltage relay

(Figure 19-6).

when overvoltage condition occurs)

Ammeter

R3 (calibrate low voltage output for

Engine compartment right side oleo

indicator deflection proportional to

support fitting (Figure 19-11).

main output)

TOT indicator

R4 (calibration)

Part of the resistor board TB9 on aft

end of TOT indicator in instrument

console.

Cigarette lighter

R9, R10, R11, R12 (reduce voltage)

Approximately the same as R1 and R2

(near TB8, Figure 19-6), or in the left

side of panel type B mounting

structure (Figure 19-10)

Instrument cluster lighting

R112 (reduce voltage)

Mounted on back of instrument cluster

(current 3-pack only)

in instrument panel.

Oil pressure gage circuit

R303, R304, R305 (calibration)

Forward of instrument cluster on panel

(current 4-pack only)

structure.

11. Voltage Reduction and Calibration

(4). Restore wiring security where nylon

Resistors

straps have been cut; use nylon twine

(30) if straps are not available.

(Ref. Table 19−5) Resistors are installed in

various circuits of the electrical system to

(5). Check repaired circuit for correct

reduce the nominal supply voltage from 24

operation.

volts to 12 volts (dropping resistor), and to

12. Start Relay

adjust circuit voltage for proper circuit

performance (calibration resistor). These

(Ref. Figure 19−11) The start relay, mounted

resistors may be identified and located by the

aft of the reverse current relay on the oleo

following:

support fitting at the right side of the engine

compartment, is a single−pole, single−throw,

A. Voltage Reduction and Calibration

normally open relay with enclosed contacts.

Resistor Replacement

The relay connects battery or external power

to the starter when the START switch on the

(1). Check that all electrical power is OFF.

pilot’s collective pitch stick is pressed. Refer to

CSP−H−3, HMI Appendix A for information

(2). Gain access to resistor location. Cut

optional engine automatic reignition compo−

nylon straps if necessary to get wire

nent used with the start relay.

slack, disconnect wiring and remove

defective resistor.

A. Start Relay Replacement

NOTE: Terminal board TB8 should be removed

(1). Check that all electrical power is OFF.

from the structure when replacementof ei−

ther resistor R1 or R2 is necessary.

(2). Slide back insulating boots and discon−

nect cable terminal attaching hardware

(3). Use a pencil type soldering iron and tin

and wiring from relay. Separately

alloy solder (48, Table 2−4) when

insulate and tie back cable terminals to

installing replacement resistor.

prevent an inadvertent short circuit.

Page 19-27

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). Remove relay mounting hardware and

14. Battery Relay

remove start relay.

The battery relay, mounted aft of the battery

(4). Check bonding surfaces for good

at Sta. 64.37, is a single−pole, single−throw,

condition. Position replacement relay

normally open relay with enclosed contacts.

on mounting surface and secure with

The relay connects the battery to the main

attaching hardware.

power bus when power selector switch is in

battery position.

(5). Connect wiring to terminals with

A. Battery Relay Replacement

washers and nuts. Slide insulating

boots over studs.

(1). Ensure all electrical power is OFF.

(6). Apply a coating of lacquer (47,

(2). If installed, disconnect and remove

Table 2−4) to all exposed electrical

battery.

studs, terminals, and associated

connecting hardware.

(3). Disconnect wires and mark wires for

reinstallation.

13. Reverse Current Relay

(4). Remove hardware (two screws, two

nuts and two washers) from relay

(Ref. Figure 19−11) The reverse current relay,

mount.

mounted on the oleo support fitting at the

right side of the engine compartment, serves to

(5). Replace relay.

isolate the battery and the 28 Vdc bus from the

generator. The relay will isolate the generator

(6). Reinstall hardware and reconnect

from the 28 Vdc bus (and battery) when the

wires.

generator switch is off, an overvoltage condi−

(7). Reinstall battery, if required.

tion exists, or when the battery voltage is

greater than the generator voltage and current

B. Battery Relay Troubleshooting

flows in the reverse direction.

(1). Connect battery. Insure instrument

A. Reverse Current Relay Replacement

panel circuit breaker is in.

(1).

Check that all electrical power is OFF.

(2). Turn power selector switch to BATT

position.

(2).

Remove terminal nuts and washers,

and disconnect electrical wiring from

(3). Check instrument panel for lights.

reverse current relay. Reinstall termi−

15. APU Relay

nal nuts and washers.

The APU relay, mounted under the right fwd

(3).

Insulate cable terminals to prevent

seat on the right hand bulkhead, is a single−

inadvertent short circuit.

pole, single−throw, normally open relay with

(4).

Remove mounting hardware and

enclosed contacts.

reverse current relay.

A. APU Relay Replacement

(5).

Check that case bond surfaces are clean

(1). Ensure all electrical power is OFF.

on replacement reverse current relay

and on mounting surface. Secure relay

(2). Remove right hand passenger footwell.

with screws, washers and nuts.

(3). Disconnect wires and mark for reinstal−

(6).

Connect electrical wiring to terminal

lation.

studs of reverse current relay. Secure

(4). Remove hardware (2 bolts, 2 nuts and 4

with washers and nuts.

washers) from relay mount.

(7).

Apply a coating of lacquer (47,

(5). Replace relay.

Table 2−4) to all exposed electrical

studs, terminals and associated

(6). Reinstall hardware and reconnect

connecting hardware.

wires.

Page 19-29

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(7). Reinstall passenger footwell.

(c).

Solder wires to replacement switch

and remove tags.

B. APU Relay Troubleshooting

(d).

Clean solder terminals and wiring

(1). Connect auxiliary power source. Ensure

adjacent to terminals with MEK (22,

instrument panel circuit breaker is in.

Table 2−4).

(2). Turn power selector switch to APU

(e).

Brush or spray switch terminals and

position.

adjacent wiring with adhesive (122)

to provide bond for potting com−

(3). Check instrument panel for lights.

pound.

(f).

Form potting mold with electrical

16. Collective Pitch Stick Switches

tape (123); Position mold around

switch terminals and attach wires as

(Ref. Figure 19−12) The collective stick

shown; then fill mold with potting

contains the START, N₂ GOV and LDG LT

compound (124). Allow potting

switches. Wires from the switches are routed

compound to cure for eight hours

through the center of the collective pitch stick

minimum.

and out through two exit holes just aft of the

stick friction gear train. The wires from the

(g).

Place check washer on replacement

collective pitch stick switches are connected to

switch and attach switch to switch

an electrical connector to facilitate removal of

plate with lockwasher and panel nut.

the complete stick assembly.

Install knob on switch and secure in

place by tightening setscrew.

A. Collective Pitch Stick Switch

Replacement

(h).

Attach switch plate to stick housing

with four washers and screws.

(1). Check that all electrical power is OFF.

(6). To replace START switch:

(2). Cut twine or nylon strap securing

wiring to collective pitch stick, and

disconnect grounding terminals.

(a). Loosen self−tapping screw in front

half of switch, unthread front half of

(3). Loosen two setscrews that secure grip

switch from switch body, and remove

switch housing to stick. Feed wire slack

switch from stick housing.

into stick while sliding switch housing

from end of stick.

(b). Unsolder electrical wires attached to

switch terminals and tag−identify to

(4). Remove four screws and washers to

facilitate reconnection.

detach switchplate.

(c). Solder wires to replacement switch

(5). To replace either N₂ governor switch or

and remove tags.

landing light switch:

(d). Position switch body in stick housing

(a). Use a small knife to cut and remove

and secure to housing by threading

potting compound from wires and

front half of switch onto switch body.

terminals at the base of the switch.

Tighten self−tapping screw to pre−

Avoid cutting wires and terminals.

vent loosening of front half of switch.

Unsolder wires and tag−identify to

facilitate reconnection.

(7). Assemble grip switch housing, stop

release spring and ring on collective

(b). Loosen knob setscrew and remove

pitch stick. Carefully draw slack wire

knob, panel nut, lockwasher, check

from stick, then tighten two housing

nut and switch.

setscrews.

Page 19-30

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(8). If nylon strap is not available, secure

The light/switches are mounted in a light/

wiring to collective pitch stick at a point

switch and horn housing installed on the hood

approximately one inch from holes with

of the instrument panel.

twine (30).

NOTE:

At intervals specified in CSP−H−4, an

(9). Connect electrical connector and attach

operational check of the battery tempera−

grounding terminal.

ture sensing equipment is to be performed.

(10). Check replacement switch for proper

A. Battery Temperature Sensing Equipment

operation by performing the engine

Maintenance

starting procedure in the Owner’s

Manual.

NOTE: For view of light/switches and wiring

inside light/switch and horn housing, refer

17. Battery Temperature Sensing Equipment

to Section 17.

(Ref. Figure 19−13) Battery temperature

(1). As required, perform an operational

sensing equipment provides a monitoring

check of battery temperature sensing

system with visual caution and warning light

equipment.

indicators that illuminate at battery over−tem−

peratures.

(2). For information on low and high

temperature switch limits, Ref. Testing

The battery temperature sensing equipment

of Battery Temperature Sensing

consists of two temperature indicator light/

Switches

switches and horn housing, interconnecting

wiring and associated attaching and mounting

(3). Troubleshoot battery temperature

hardware. The equipment provides an amber

sensing equipment according to

caution light indication when battery tempera−

information on troubleshooting caution

ture reaches 140°F, and a red warning light

and warning light indicators.

indication at 160°F. Both indicator light/

B. Battery Temperature Sensing Equipment

switches contain a built−in press−to−test

Operational Check

switch for testing internal lamps.

NOTE: This operational check is required at in−

The indicator light/switches are electrically

tervals specified in CSP−H−4.

interconnected to low and high temperature

sensing switches installed on a buss bar of the

(1). Remove battery from helicopter.

ni−cad battery (Ref. Figure 19−14). The

switches are part of and are furnished with the

(2). Check low and high temperatures

battery.

sensing switches on battery bus bar for

correct operation at specified tempera−

A rise in battery temperature to 140°F causes

tures.

the low temperature switch to close and apply

+dc voltage from the battery to illuminate the

(3). Install battery in helicopter.

amber caution light. An increase of battery

temperature to 160°F causes the red warning

(4). Inspect electrical wiring for security,

light to illuminate in the same manner.

physical damage and continuity.

When depressed, the press−to−test switch on

(5). With electrical power ON and PNL LT

each indicator applies +28 Vdc from the panel

circuit breaker CB104 ON, alternately

lights circuit breaker CB104 to the associated

depress and check that both 140°F and

light indicator for testing internal lamp

160°F light indicators illuminate.

illumination.

Replace any defective lamps.

Page 19-32

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

RED 160° WARNING

AMBER 140° CAUTION

LIGHT SWITCH

LIGHTS/SWITCH AND

HORN HOUSING

HOUSING

PLATE

INSTRUMENT PANEL

CENTER FAIRING

ENGINE OUT

WARNING HORN

LIGHT INDICATORS IN HOUSING

BATTERY CONNECTOR

(NOTES 5, 7)

LOW TEMPERATURE (140°F)

XDS24

SWITCH

(NOTE 3)

J529

P529

140°F

YELLOW

E559AA22

140° CAUTION

(NOTE 1)

LIGHT−SWITCH

160°F

BUS BAR

RED

E559AC22

AMBER

(NOTES 5, 6)

(NOTE 1)

160° WARNING

LIGHT−SWITCH

HIGH TEMPERATURE

RED

(160°F) SWITCH (NOTE 4)

XDS25

BATTERY

E559AB22

E559A22

E508A22 (NOTE 2)

+28 VDC FROM

PANEL LIGHTS

CIRCUIT BREAKER

E559AD22N

E510A22

WIRING DIAGRAM (NOTE 4)

NOTES:

PART OF WIRING HARNESS: ROUTE WITH EXISTING WIRING.

APPLIES ONLY TO 500S WITH TYPE A INSTRUMENT PANEL

(REF. SEC. 17) AND INCREASED GROSS WEIGHT CAPABILITY.

HIGH TEMPERATURE SWITCH IDENTIFIED BY RED MARK ON BUS BAR;

LOW TEMPERATURE SWITCH BY YELLOW MARK.

THIS WIRING DIAGRAM SHOULD BE USED WITH APPLICABLE ELECTRICAL

SYSTEM WIRING DIAGRAM IN SECTION 20 FOR COMPLETE CIRCUIT

IDENTIFICATION.

PART OF BATTERY.

WHEN SWITCH CLOSES, +VDC IS APPLIED FROM BUS BAR FOR LIGHT.

ON LATER BATTERIES, YELLOW CONNECTS TO J108−D AND RED

CONNECTS TO J108−B.

30-204A

Figure 19-13. Battery Temperature Sensing Equipment

Page 19-33

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

18. Battery

A. Battery Maintenance

(Ref. Figure 19−14) The battery is a recharge−

Handling, servicing precautions, servicing,

able, nominal 24−volt, 13−ampere−hour,

charging and cleaning instructions for the

l9−cell, nickel cadmium battery capable of

battery are provided in Section 2.

starting the engine in temperatures from

−25 ° F (−32°C) to +130° F (+54°C).

B. Battery Replacement

Early batteries are connected to the electrical

(1). Check that all electrical power is OFF.

system by a two−pin keyed female connector

receptacle located at the inboard end of the

(2). Raise pilot’s floor left access door. For

battery case; the connector is provided with a

better access, hand−press access door

smaller key pin to prevent polarity reversal

pivot pins from hinge points and

between the mating halves of the connector.

remove door.

Later batteries have a five−socket receptacle

connecting the battery to the electrical system

If corrosion is present be−

and temperature sensors to the battery

WARNING

tween the plug and recep−

temperature warning lights. The arrangement

tacle, the plug will be difficult to re−

of pins in this receptacle prevents improper

move. If excessive force is used to turn

connection of the connector halves.

the plug on the hex nut−secured recep−

tacle (Figure 19−14), it may rotate and

The 19 identical and individually replaceable

cause the internal leads to short. When

battery cells are contained in separate molded

normally required hand−pressure will

nylon cases and interconnected by bus bars.

not release the plug, apply hydraulic

oil or equivalent, to the threaded con−

nection. Allow enough time for the cor−

The cells are equipped with removable filler

rosion deposits to soften so that plug

cap vent plugs that allow gasses from the cell

can be removed.

to escape through the vent when the battery is

in, or near, the up−right position. The filler cap

(3). Disconnect battery plug and tempera−

vent plugs also prevent electrolyte spillage

ture sensing connector, or single plug if

when the battery is tipped or inverted.

single connector is used.

A mixture of potassium hydroxide and water is

(4). Remove four screws and washers that

used as the electrolyte; however, only pure

secure battery to mounting flanges.

distilled water is used for replenishment

purposes.

Avoid tilting the connector end

CAUTION

of the battery downward during

The battery case, cover and end plates are

the removal and handling after removal.

constructed from epoxy−impregnated fiber−

Any water or electrolyte in the battery case

glass.

will collect at the connector leads and short−

ing may occur.

The battery is secured to brackets on the

pilot’s compartment floor structure by four

(5). Lift battery and cover from the under−

screws and washers installed through the

floor compartment. Using suitable

cover and battery case.

hardware, secure the cover to the

battery case, Place battery in a pro−

Gases generated within the battery are vented

tected area away from any lead−acid

from the cells to the inside of the cover and out

type battery.

through the ventilation gap between each

upper side edge of the case and cover. Refer to

(6). Install serviced battery and secure

CSP−H−3, HMI Appx A for installation

battery and cover to mounting brackets

instructions of a battery compartment ventila−

with four mounting screws and wash−

tion scoop.

ers.

Page 19-34

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

HI−LIMIT SWITCH

COVER

NOTE 1

FIBERGLASS

CELL HOLD−

SLEEVING

DOWN BAR

FILLER CAP

VENT PLUG

LOW−LIMIT

TERMINAL SCREW

SWITCH

(NOTE 2)

BAFFLE

TERMINAL WASHER

BUS BAR

HIGH TEMPERATURE SWITCH

(RED PAINT MARK)

FILLER

TERMINAL

VENT

RECEPTACLE

CELL

BUSS WIRE

(NOTE 3)

NOTE 4

VENTILATION CAP

(BOTH SIDES)

BENDIX 10−87324−9S

RECEPTACLE (NOTE 6)

NOTE 1

NYLON

SEALANT

SEPARATOR

(NOTE 6)

COVER WITH

CASE

SEALANT

(NOTE 7)

RECEPTACLE BUS STRIP

(NOTE 5)

GUSSET

(OPT)

CONNECTOR SEPARATOR

(VINYL PLASTIC−COVERED

CORROSION RESISTANT

STEEL SHEET)

NOTES:

SCREW, WASHER AND NUT SHOULD NOT BE USED FOR

BENDIX 10−87324−9S

SHIPMENT, HANDLING AND STORAGE.

RECEPTACLE (NOTE 5)

SCREW TORQUE:

MARATHON (SONOTONE); 15−18 IN.−LBS. (1.69−2.03 NM).

GULTON; 26−30 IN.−LBS. (2.94−3.39 NM).

CAUTION: COMPLETE SET OF EITHER GULTON CELLS

OR MARATHON (SONOTONE) CELLS MUST BE USED. mIXING

PLASTIC

OF GULTON AND MARATHON (SONOTONE) CELLS IS NOT

WASHER

ALLOWED. REFER TO THE APPLICABLE MANUFACTURER’S

PUBLICATION.

RECEPTACLE

CELLS ARE SHOWN NUMBERED FOR REFERENCE ONLY.

NUT

CONNECTOR BUS STRIPS AND BACK OF CONNECTOR

COVERED TO WITHIN 0.62 IN. (15.748 MM) OF CELL

NOTE 7

TERMINALS WITH 0.060 IN. (1.524 MM) THICK COATING OF

SEALANT (3, TABLE 2−4).

LOCKWIRE HOLES

CONNECTOR BACK FILLED AND CONNECTOR BUS WIRES

COVERED 0.25 IN. (6.35 MM) BEYOND ENDS OF RECEPTACLE

TERMINALS WITH SEALANT (3). INSULATION SLEEVING

REMOVED FROM CONNECTOR BUS LEADS UNDER SEALANT.

COVER WITH SEALANT (3).

30−110E

Figure

19-14. Replacement of Battery Components

Page 19-35

Revision 15

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(7). Apply a generous coating of dielectric

(2). Remove the bus bar equipped with

compound (185, Table 2−4) to the male

sensors (sensors and connecting wires

and female connector pins and sockets

attached).

and also the connector plug and

(3). Using a container, oil or water, ther−

receptacle threads. All surfaces should

mometer and heat source, submerge

be coated, Connect battery plug and

sensor bus bar and check at battery

temperature sensing connector or single

sensor connector plug, or single connec−

plug if used; then wipe away excess

tor receptacle pins A and C, for proper

compound.

heat range.

(8). Reinstall floor access door.

(a). Low temperature switch −

Closes on temperature rise at

C. Battery Inspection

140° ±8°F.

Opens on temperature decrease at

(1). Check that all electrical power is OFF.

100° ±8°F.

(2). Remove screws and washers that

(b). High temperature switch −

secure battery to mounting brackets

Closes on temperature rise at

and remove cover.

160° ±8°F.

Review the general battery

Opens on temperature decrease at −

WARNING

130° ±8°F.

handling and servicing pre−

cautions outlined in Section 2 before

(4). Clean the bus bar with MEK (22,

performing the following operations.

Table 2−4) and reinstall.

(3). Inspect tops of cells for dust, dirt, white

NOTE: The sensors may be removed from the

powder (potassium carbonate) or

bus bar for testing or replacement by remov−

spewed electrolyte. Refer to Section 2

ing the sealant and un−soldering wire con−

for cleaning instructions.

nections.

(4). Inspect receptacle bus strips, bus bars

(5). Reinstall battery in helicopter.

and screws for security and evidence of

(6). Inspect electrical wiring for security,

damage.

physical damage and continuity.

(5). Inspect cells for cracks, evidence of

(7). Perform a power ON operational check

overheating or other physical damage.

of battery temperature sensing equip−

Inspect cell bus bars for greenish color

ment.

indicating acid contamination. Replace

E. Repair of Battery

battery if any such damage is detected.

NOTE: Complete disassembly and reassembly

Electrolyte level inspection

of battery is covered in the following proce−

CAUTION

should be accomplished only

dures. Follow the procedures, in sequence,

when the battery has been fully charged and

until the part or parts requiring repair or re−

then allowed to rest for a period of 1 to 2

placement have been removed and rein−

hours after charging. If the helicopter has

stalled. Refer to battery manufacturer’s

operated for a minimum of one hour or more

maintenance instructions (Ref. Table 2−15)

of continuous flight, the battery may be con−

for repairs not covered in the procedures

sidered charged.

Discharge the battery before

(6). Reinstall cover and secure with four

WARNING

attempting disassembly. If

screws and washers.

the battery bas not been discharged,

serious personal burns may result and

D. Testing of Battery Temperature Sensing

damage to the battery may occur. Refer

Switches

to Deep Cycling of Battery, Section 2.

NOTE: This test is required at intervals speci−

(1). Removing Bus Bars.

fied in CSP−H−4, HMI Appendix B.

(a). Remove the terminal screw and

(1). Remove the battery from helicopter.

washer from each end of the bus bar.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: Refer to Figure 19−14 and note the loca−

(e). For batteries with a dual connector,

tion of the bus bar with temperature sensing

cut and remove the lockwire from the

switches. If required, remove sealant, un−

receptacle nut. Remove the receptacle

solder wire connections and remove

with attached receptacle bus wires or

switches, according to step (7).

strips from the case.

(b). Lift the bus bar from the cell.

(f). For batteries with a single connector,

remove the four nuts, washers, and

(c). Clean bus bar with methyl−ethyl−ke−

screws that secure the receptacle to

tone (22, Table 2−4).

the battery case and pull the recep−

tacle forward to gain access to

(2). Removing Cells.

attached wires.

NOTE: Each cell is removed from the battery

(g). Remove sealant, if used, and unsold−

case with a cell puller. Two battery bus bars

er wires attached to the receptacle

and a piece of cord may be used to fabricate

terminals.

a puller. Attach the cord to the hole at one

end of each bus bar. Initial removal of either

(4). Replacing Battery Case

cell No. 5 or No. 6 will aid in the removal of

(a). Disassemble the battery, steps (1).

other cells.

thru (3).

(a). Remove screws and washers that

(b). Using a stiff nylon brush and a

secure hold−down bars to battery

3−percent boric acid solution, wash

case.

the replacement battery case; then

flush with clean water (cold if

(b). Remove the battery bus bars and/or

possible) to ensure that the case is

bus wires or strips from the cells.

clean. Dry the case with a clean

cloth, and then air−dry in a warm

(c). Remove nylon separator when

area for at least 1 hour.

required to permit removal of cells.

(c). Reassemble battery components into

(d). Attach the cell puller to the cell

the new case, steps (5). and (6).

terminals; use the terminal screws

and washers to secure the puller to

(d). Deep cycle the battery (Section 2).

the cell.

(5). Installing Receptacle

(e). Lift the cell from the battery case. If

Observe correct polarity when

necessary, slightly rock the cell from

CAUTION

connecting the receptacle bus

side to side to work it loose.

wires or strips to the receptacle. Reversed

NOTE: Observe the polarity of the removed cell

connections can damage the battery when it

to prevent reinserting the cell in reverse po−

is connected to the helicopter electrical sys−

larity.

tem.

(a). Using a tin−alloy solder (48), solder

(3). Removing Receptacle

the two receptacle bus wires or strips

(a). Loosen and remove the two terminal

and the two temperature sensor

screws and washers that secure the

wires (single connector) to the

two receptacle bus wires or strips to

terminals at the back of the recep−

adjacent cells.

tacle.

(b). Remove the bus bar that connects

(b). For dual connector batteries, insert

cells No. 1 and No. 2.

the receptacle into the battery case

and securely tighten the receptacle

(c). Remove the cell hold−down bar from

nut. Using lockwire (2), safety the

the same side of the battery as the

nut to the holes in the case.

connector separator.

(c). For single connector batteries, secure

(d). Remove the nylon separator and cell

the receptacle to the battery case

No. 1.

with four screws, washers and nuts.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(d).

For dual connector batteries, fill

(e). Spray a thin film of WD−40 (101)

receptacle back and cover bus wires

over entire top surface of battery and

or strips with sealant (3). For recep−

inside connector receptacle or coat all

tacle with bus wires, the receptacle

exposed metal parts with petrolatum

back and wires are covered 0.250

(34).

inch (6.35 mm) beyond rear of

(f). Deep cycle the battery (Section 2),

receptacle terminals. Insulation

before returning the battery to

sleeving must be removed from wires

service.

under sealant. For receptacle with

bus strips, receptacle back and strips

(7). Replacement of Temperature Sensing

are covered to within 0.62 inch

Switches

(15.748 mm) of cell terminals with

0.060 inch (15.24 mm) thick sealant

(a). Remove sealant covering switches

coating.

and unsolder wire connections,

remove switch.

(e).

Position the connector separator

(b). Install correct replacement switch in

inside the battery case so that open

location shown in Figure 19−14 and

end butts against end of case, enclos−

torque to 5 − 15 inch−pounds (0.56

ing the two receptacle bus wires or

− 1.69 Nm).

strips and the receptacle.

(c). Install fiberglass sleeving and solder

(f).

Install the nylon separator and

wire connections; red wire to high

removed cells, step (6).

temperature switch and yellow to low

temperature switch.

(6). Installing Cells

(d). Cover the switch connections with

sealant (3).

Do not intermix Gulton and

CAUTION

Marathon (Sonotone) cells. Re−

(e). Check that high temperature switch

fer to the applicable manufacturer ’s publi−

is identified by a red paint mark on

cation.

the bus bar and renew, if required.

19. Starter/Generator

(a). Obtain a new or serviceable cell to

replace a defective cell.

(Ref. Figure 19−15) A combined starter and

generator is used to start the engine and to

(b). Check that the cell is clean and

provide primary 28−volt, direct−current power

position it in the battery case for

for operation of the electrical system.

correct polarity orientation.

The starter/generator, a self−cooled unit, is

clamp−attached to a quick−disconnect mount−

NOTE: When replacing a complete set of cells,

ing flange on the engine power and accessory

install cells in order, No. 1 thru No. 9, the

gearbox.

nylon separator, No. 19. and then No. 10

thru No. 18.

A shear point is incorporated in the generator

drive shaft to protect the engine drive from

(c). Connect the bus bars and/or bus

excessive torque loads.

wires or strips with terminal screws

The starter system consists of the starter/gen−

and washers; the cup side of the

erator, start relay, voltage regulator and a

washer must be down. Torque screws

START switch located in the pilot’s collective

to 15 − 18 inch−pounds (1.69 − 2.03

pitch stick.

Nm) for Marathon/ Sonotone or 26 −

30 inch−pounds (2.94 − 3.39 Nm)

When pressed, the START switch energizes

for Gulton.

the solenoid of the start relay and supplies

power from the power selector switch bus

(d). Install the hold−down bars on the

through the BAT terminal of the reverse

case.

current relay and start relay to the start

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CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 11