C-130T. FLIGHT MANUAL (2006)

01-75GAL-1

Figure 2-70. Emergency Depressurization Handle

2.17.4.6 Pressurization Test Valves

An isobaric and an atmospheric test valve, labeled NO. 1 and NO. 2 respectively, are located on the left side of the

overhead control panel. These valves, wired in the open position, are intended only for ground use.

2.17.4.7 Differential Pressure Gauge

The differential pressure gauge, located on the air-conditioning and pressurization control panel (see Figure 2-66),

senses both cabin and atmospheric pressures and indicates the pressure differential in inches of mercury.

2.17.4.8 Indicator

The cabin rate-of-climb indicator, which shows the rate of change of cabin altitude in feet per minute, is mounted

on the air-conditioning and pressurization control panel (see Figure 2-66).

2.17.4.9 Cabin Altimeter

The cabin altimeter (see Figure 2-71) in the copilot instrument panel indicates cabin air pressure altitude within the

range of 0 to 50,000 feet.

2.18

ANTI-ICING AND DEICING SYSTEMS

Anti-icing systems, which can be used to prevent the formation of ice on critical areas of the aircraft, and de-icing

systems, which will remove ice after it is formed, are installed on the aircraft. Heat for the systems is obtained either

by the use of electrical heating elements or by heated air drawn from the compressor of each engine.

2-141

ORIGINAL

01-75GAL-1

Figure 2-71. Cabin Altimeter

Anti-icing systems using heated air from the bleed-air system serve thewing and empennage leading edges, thenose

radome, and the engine inlet air and oil cooler scoops. Anti-icing of the engine compressor inlet vanes also is

accomplished by heated air, but this is supplied directly from the engine compressor and not through the bleed-air

system.

Anti-icing systems using heat from electrical sources are installed for the windshield, pitot tubes, and the forward

section and afterbody of the propeller spinner. De-icing of the propeller blades and rear section of the propeller

spinner also is accomplished electrically. An ice detection system may be used to achieve automatic operation of the

following anti-icing and deicing systems:

1. Engine inlet airscoop anti-icing.

2. Compressor inlet vane anti-icing.

3. Propeller spinner forward section and afterbody anti-icing.

4. Propeller blade deicing.

5. Propeller spinner middle and rear section deicing.

6. Propeller spinner plateaus deicing.

2.18.1 Wing and Empennage Leading Edge Anti-Icing System

The leading edge anti-icing system (see Figure 2-72) is divided into six sections, each consisting of a shutoff valve,

ejectors, and control components. The shutoff valves control the flow of air from the bleed-air system to the ejectors,

where it is ejected through small nozzles into mixing chambers. The hot bleed air at approximately 600 _F is mixed

with the ambient air drawn into the mixing chambers. The resultant mixed air at approximately 350 _F flows through

passages next to the leading edge skin. Since some of the air leaving the passages is drawn back in for recirculation,

a lower percentage of bleed air is required for continuous anti-icing. An overheat warning system is installed in the

leading edge area.

When the temperature in the leading edge area reaches approximately 200 _F, the overheat warning light for that area

is energized and the light illuminates.

ORIGINAL

2-142

01-75GAL-1

Figure 2-72. Anti-Icing System (Sheet 2)

2.18.1.1 WING and EMPENNAGE ANTI-ICING Switches

The WING and EMPENNAGE ANTI-ICING switches are two-position (ON, OFF) toggle switches, located on the

anti-icing and deicing system control panel (see Figure 2-73). When the switches are placed in the ON position,

solenoids on theanti-icing shutoffvalves areenergized and thevalves control theflowofbleedairtotheleadingedge

air ejectors. When the switches are in the OFF position, the anti-icing regulators shut off the flow of bleed air.

Electrical power for control of the wing and empennage anti-icing shutoff valves is supplied from the essential dc

bus, through the WING and EMPENNAGE ICE CONTROL circuit breakers on the copilot lower circuit breaker

panel.

2.18.1.2 Leading Edge Temperature Indicators

Six leading edge temperature indicators, one for each section of the anti-icing system, are located on the anti-icing

and deicing system control panel (see Figure 2-73). Each indicator is connected to a resistance bulb located in the

leading edge area. The resistance bulbs are placed so that they sense the temperature of the air in the area aft of the

leading edge skin, not the hot air passing next to the skin. Electrical power for the indicators is supplied from the

essential dc bus, through the WING and EMPENNAGE TEMP INDICATOR circuit breaker on the copilot lower

circuit breaker panel.

ORIGINAL

2-144

01-75GAL-1

2.18.1.3 Leading Edge Over Temperature Warning Lights

Six OVERTEMPERATURE WARNING lights, one for each section of the leading edge anti-icing system, are

located below the temperature indicators on the anti-icing and deicing system control panel (see Figure 2-73). When

the temperature in the leading edge reaches approximately 200 _F, the warning light for that area illuminates.

Electrical power for the lights is supplied from the essential dc bus through the WING and EMPENNAGE

OVERHEAT LIGHTS circuit breaker on the copilot lower circuit breaker panel.

2.18.1.4 Normal Operation of Leading Edge Anti-Icing System

The wing and empennage leading edge anti-icing system is turned on or off by the ANTI-ICING switches on the

anti-icing and deicing system control panel. Regulation of temperatures within the leading edges is achieved

automatically by thermostatic control of the valves permitting entry of bleed air to the system ejectors. The

temperature indicators on the control panel, however, should be monitored while the system is operating since an

emergency condition will exist if either the associated indicators or the warning lights show an overheated condition

in any section.

CAUTION

The leading edge anti-icing system must not be used to remove ice from

surfaces when the aircraft is on the ground. With no airflow over the

surface, the air within the leading edge area quickly rises in temperature and

the excessive heat damages fuel tank sealants, paint, structure, and other

equipment. If the system is operated for testing, constant monitoring of the

temperature indicators must be maintained and the system must not remain

on for more than 30 seconds.

2.18.2 Radome Anti-Icing System

Deactivated.

2.18.3 Engine Inlet Air Duct Anti-Icing Systems

Two systems (see Figure 2-72) are provided for engine inlet air duct anti-icing. One system routes bleed air from the

bleed-air system to passages in the engine inlet airscoop and oil cooler scoop to heat the scoops.

The other system routes air from the compressor diffuser section of the engine to passages in the compressor inlet

vanes. The scoop anti-icing airflow is shut off by a solenoid valve that is energized closed. The air flows when the

valve is deenergized open. The vane anti-icing airflow is controlled by two pressure-actuated valves, which are

controlled by a single solenoid valve. When the solenoid valve is energized, the pressure-actuated valves shut off

the airflow, and, when thesolenoid valveis deenergized, the pressure-actuated valves open. Both thescoop and vane

anti-icing systems are termed fail-safe, meaning that anti-icing is provided when the system power supply is lost.

The electrical control circuits are interconnected with the ice detection system so that the duct anti-icing can be turned

on automatically when the detection system senses icing.

2.18.3.1 ENGINE INLET AIR DUCT ANTI-ICING Switches

Four ENGINE INLET AIR DUCT ANTI-ICING switches are located on the anti-icing and deicing systems control

panel (see Figure 2-73). Each switch has ON and OFF positions. If a switch is in the ON position, the scoop and vane

anti-icing systems for that engine are turned on if the PROP & ENG ANTI-ICING MASTER switch is in MANUAL.

If the master switch is in the AUTO position, anti-icing is turned on when the ice detection system detects ice. When

an ENGINE INLET AIR DUCT ANTI-ICING switch is in the OFF position, both scoop and vane anti-icing valves

for that engine close to shut off the anti-icing airflow.

2.18.4 Propeller Anti-Icing and Deicing Systems

The propeller spinner and blades are equipped with heating elements for anti-icing and deicing (see Figure 2-74).

ORIGINAL

2-146

01-75GAL-1

2.18.4.1 Propeller Anti-Icing System

The forward section of the spinner and the propeller afterbody are covered by electrical-resistance heating elements

to provide anti-icing. Phase A primary ac power is applied to the heating elements to warm the surface of thespinner

and prevent the formation of ice. The ac power is applied by relays controlled by dc control circuits that are protected

by the SPINNER ANTI-ICING circuit breakers on the pilot upper circuit breaker panel. The control circuits are

interconnected with the ice detection system so that the propeller anti-icing can be turned on automatically when the

detection system senses icing. The propeller anti-icing is a continuous-heating-type system.

2.18.4.2 Propeller Deicing System

The aft portion of the front spinner section, the rear rotating spinner section, the spinner plateaus, and the leading

edges and fairing of the propeller blades contain heating elements for deicing the surfaces. The aft portion of the front

spinner section, along with the forward part of the rear rotating spinner section and the spinner plateaus, use phase

B p rimary ac power and are protected by the SPINNER DE-ICING circuit breaker on the upper main ac distribution

panel. The aft portion of the rear rotating spinner section and the leading edges and fairing of the propeller blades

use phase C primary ac power and are protected by the BLADE DE-ICING circuit breaker on the upper main ac

distribution panel. The heating elements are supplied with 115-Vac power from the RH ac bus through the BLADE

and SPINNER DE-ICING circuit breakers on the upper main ac distribution panel. The control circuits for the

propeller deicing, like the control circuits for the propeller anti-icing system, are connected to the ice detection system

so that they may be turned on automatically. The application of spinner and blade deicing power to the heating

elements is controlled by the deicing timer. The timer receives 28-Vdc power from the essential dc bus through the

PROPELLER DE-ICING TIMER circuit breakeron thecopilot lowercircuit breakerpanel. Thetimer applies power

to theheating elements ofonly onepropellerat atime; theelements of each propellerareenergized15 secondsduring

each 1-minute cycle.

2.18.4.3 PROPELLER ICE CONTROL Switches

Four PROPELLER ICE CONTROL switches are located on the anti-icing and deicing systems control panel (see

Figure 2-73). These two-position (ON, OFF) toggle switches control the propeller anti-icing and deicing systems.

When a switch is placed in the ON position and the PROP & ENG ANTI-ICING MASTER switch is in the MANUAL

position, the anti-icing and deicing systems for the corresponding propeller are energized. If a switch is positioned

to ON while the PROP & ENGINE ANTI-ICING MASTER switch is in the AUTO position, the anti-icing and

deicing systems are energized only when the ice detection system detects icing. When a switch is placed in the OFF

position, the anti-icing and de-icing systems for the corresponding propeller are deenergized.

2.18.4.4 Anti-Icing and Deicing Ammeters

Three ammeters located on the anti-icing and deicing systems control panel (see Figure 2-73) indicate the amperage

of the various phases of primary ac power drawn for the propeller anti-icing and deicing systems. The SPINNER

ANTI-ICING ammeter indicates the amperage of phase A power drawn for anti-icing; the SPINNER DE-ICING

ammeter indicates the amperage of phase B power drawn for deicing; and the BLADE DE-ICING ammeter indicates

the amperage of phase C power drawn for deicing.

2.18.5 Ice Detection System

The ice detection system is used as an automatic control for turning on the radome anti-icing, engine inlet air duct

anti-icing, and propeller anti-icing and deicing systems. The detection system consists of a PROP & ENG

ANTI-ICING MASTER switch, two sets of detector units, indicator lights, a test switch, and control relays. Each

set of detection units has a detector and an interpreter. Each detector includes a probe: one is mounted in the No. 2

engine inlet air duct, and the other is in the No. 3 engine duct. The detection units are armed by dc power applied

through theenginestarting circuits, and they areoperativewhen theNo. 2 orNo. 3 engines arerunning and thePROP

& ENG ANTI-ICING MASTER switch is in AUTO. If either probe becomes iced over while the engine in which

it is installed is running, and if the PROP & ENG ANTI-ICING MASTER switch is in the AUTO position at that

ORIGINAL

2-148

01-75GAL-1

time, the detection units trigger a control relay. This relay turns on the anti-icing and deicing systems if the switches

for those systems are in the ON or AUTO positions. The relay also turns on an indicator light. The ice detection system

does not turn off the anti-icing and de-icing systems automatically when icing conditions no longer exist, but the

master switch can be held at the RESET position to turn them all off simultaneously. Timers in the ice detection

systemoperateaftertheNo.2andNo.3enginesareshutdownanddisarmthedetectionsystem.Ifanyoftheanti-icing

or deicing systems have been left in automatic operation, they are turned off upon disarming of the detection system

at engine shutdown.

2.18.5.1 PROP & ENGINE ANTI-ICING MASTER Switch

The PROP & ENG ANTI-ICING MASTER switch is located on the anti-icing and deicing systems control panel

(see Figure 2-73). It has three positions: AUTO, MANUAL, and RESET. When in the AUTO position, it permits

control of the radome anti-icing, engine inlet air duct anti-icing, and propeller anti-icing and deicing systems by the

ice detection system. The AUTO position is also used to permit testing of the ice detection system. When in the

MANUAL position, the switch permits control of the anti-icing and deicing systems by the individual control

switches for the systems. The RESET position is a momentary position used to turn off the anti-icing and deicing

systems when icing conditions no longer exist. When the switch is positioned at RESET and allowed to return to

AUTO, the ice detection system remains armed; therefore, it will automatically turn on the anti-icing and deicing

systems again if it senses icing.

2.18.5.2 TEST Switch

The TEST switch is located on the ice detection panel (see Figure 2-75). It has NO. 2 and NO. 3 momentary positions

and a center off position. It is used to test operation of the two sets of ice detector units by simulating ice detections.

If it is held in the NO. 2 position while the No. 2 engine is running and the PROP & ENG ANTI-ICING MASTER

switch is in AUTO, the ON indicator light on the ice detection panel illuminates to indicate that the ice detection

system has triggered the control relay that turns on the anti-icing and deicing systems. The NO. 3 position of the

switch is used in thesamemannertotest operationoftheothersetofdetectorunits. AftertheTESTswitch isoperated

to either position, the PROP & ENG ANTI-ICING MASTER switch must be held at RESET momentarily in unlock

the control relay and to rearm the detection system.

Figure 2-75. Ice Detection Panel

2-149

ORIGINAL

01-75GAL-1

2.18.5.3 ON Light and PRESS FOR LIGHT OUT Switch

The ON light and the PRESS FOR LIGHT OUT switch are located on the ice detection panel (see Figure 2-75). The

indicator light is turned on by the ice detection system whenever it detects ice while the PROP & ENG ANTI-ICING

MASTER switch is in the AUTO position. When lighted, it indicates that icing has been detected by probes in the

engine inlet airscoops and that anti-icing systems have been turned on automatically if the individual system switches

are set at ON or AUTO. It also lights when the TEST switch is operated and, then, indicates that the detection units

are functioning. The momentary light out switch can be operated to turn the light off. If the PROP & ENG

ANTI-ICING MASTER switch is held in the RESET position to turn off the anti-icing and deicing systems, the light

remains off if icing no longer exists.

2.18.5.4 NO ICE Light

The NO ICE light is on the ice detection panel (see Figure 2-75). It is turned on when the probes of the detection

system areno longericingand indicatesthat theanti-icing anddeicing systemscan beturned off.IfthePROP &ENG

ANTI-ICING MASTER switch is held in the RESET position to turn the anti-icing and deicing systems off, the light

also goes off.

2.18.6 Pitot Tube Anti-Icing System

Pitot-static tube anti-icing is provided to the four pitot-static tubes by ac electric heating elements. The heating

elements are energized by 115-volt, single-phase ac power from the essential ac bus through the PITOT HEAT NO.

1, NO. 2, NO. 3 and NO. 4 circuit breakers on the pilot side circuit breaker panel. Control of the pitot-static tube

anti-icing system is provided by the PITOT HEAT switches located on the overhead anti-icing control panel. Two

PITOT HEAT OFF indicator lights are installed on the main instrument panel to inform the pilot of system status.

2.18.6.1 PITOT HEAT Switches

The pilot and copilot PITOT HEAT switches are located on the anti-icing and deicing systems control panel (see

Figure 2-73). These two-position toggle switches have ON and OFF positions. The PITOT HEAT PILOTS switch

energizes the No. 1 (upper left side) and the No. 3 (lower right side) pitot-static tube heating elements. The PITOT

HEAT COPILOTS switch energizes the No. 2 (upper right side) and the No. 4 (lower left side) pitot-static tube

heating elements. When a switch is placed in the ON position, the heating elements for the corresponding pitot tubes

are energized and the corresponding PITOT HEAT OFF indicator light is extinguished. When the switch is in the

OFF position, the corresponding heating elements are deenergized and the corresponding PITOT HEAT OFF

indicator light is illuminated.

2.18.6.2 PITOT HEAT OFF Lights

Two amber PITOT HEAT OFF indicator lights are installed on the main instrument panel to show that the affected

system is turned off, or, if the system is turned on to show that a heating element is inoperative (see Figures 2-78

and 2-79). The indicator lights use 28-Vdc power from the isolated dc bus through the PITOT HEATER IND circuit

breaker on the pilot side circuit breaker panel.

2.18.7 Windshield Anti-Icing System

The three windshields, the two windows on each side of the windshields, and the two lower windows in front of the

pilot are NESA-type. These panels are heated by applying unregulated ac power from the left-hand ac bus to a

resistance material between the layers of glass. The ac power is applied by automatic dc control systems that cycle

to maintain window temperature within specific limits. A center windshield system controls heating of the three

center windshields, and a side and lower system controls heating of the side and lower windows. The two systems

are identical except for the amount of total ac power provided. Provisions are made for selecting either a normal or

ORIGINAL

2-150

01-75GAL-1

highrateofheating.Whenahighrateisselected,highervoltageisappliedforshorterperiodsoftimesothattheNESA

heats more rapidly, but not to a higher temperature. Provisions are also made for controlling the temperature increase

manually when the NESA panels are extremely cold. The control systems do not function automatically when

window temperature is below -45 _F.

CAUTION

Operation ofNESA anti-icing when outsideairtemperatureis above27 _C

(81 _F) will increase the possibility of delamination within the NESA

panels.

2.18.7.1 NESA WINDSHIELD Switches

The NESA WINDSHIELD switches are on the anti-icing and deicing systems control panel (see Figure 2-73). Each

switch has NORMAL, OFF, and HI positions. When the center windshield switch is in the NORMAL position, the

three center windshields are heated at the normal rate. If the switch is positioned to HI, the three center windshields

have higher voltage applied to the heating material so that they heat more rapidly. Heating of the side and lower

windows is controlled in the same manner by the side and lower windshield switch.

2.18.7.2 NESA WINDSHIELD COLD START Switches

The COLD START switches are located on the anti-icing and deicing systems control panel (see Figure 2-73) next

to theNESA WINDSHIELD control switches. TheCOLD START switchesarepush-typemomentary switches.The

purpose of the switches is to provide manual control of windshield heating to raise the windshield temperature

gradually from extremely cold temperatures to prevent damaging the glass panels. If the temperature of the

windshield panels is below -45 _F, the control systems do not function automatically. Pressing the COLD START

switches causes the control systems to apply ac power to the windshield panels while the switches are held.

2.18.8 Nacelle Preheat System (If Installed)

Note

The NACELLE PREHEAT system is inoperative due to the NACELLE

PREHEAT valve not being installed.

When the nacelle preheat valves are installed, the nacelle preheat system allows hot air from the bleed-air system to

flow into the nacelle to heat the engine and nacelle equipment before starting the engine. A solenoid valve and diffuser

in each nacellecontrols theairflow. Theenginebleed-airregulatorin anacellemust beopen beforebleed air can flow

to the preheat valve; the ENGINE BLEED AIR switch must be in OVRD. The preheat valves are controlled by four

nacelle preheat switches on the anti-icing and deicing systems control panel (see Figure 2-73). The control circuits

for the valves are energized by 28-Vdc power from the isolated dc bus through the NACELLE PREHEAT circuit

breakers on the copilot lower circuit breaker panel only while the corresponding engine condition levers are in the

GROUND STOP or FEATHER position and the aircraft is on the ground.

2.18.8.1 NACELLE PREHEAT Switches

The four NACELLE PREHEAT switches, located on the anti-icing and deicing systems control panel, are

two-position (ON, OFF) toggle switches (see Figure 2-73). When a switch is placed in the ON position while the

aircraft is on the ground and the corresponding engine condition lever is at GROUND STOP or FEATHER, the

nacelle preheat valve (when installed) is energized open and remains open as long as the switch is in the ON position.

Placing the NACELLE PREHEAT switch in the OFF position deenergizes the valve (when installed) closed.

2-151

ORIGINAL

01-75GAL-1

Note

Nacelle preheat is operational only when the touchdown switch is closed,

that is, when the aircraft is on the ground.

2.19

AUXILIARY POWER UNIT

The APU (see Figure 2-76), located forward in the left wheelwell, supplies air for ground operation of the

air-conditioning systems, for engine starting, and provides shaft power to drive a 40-Kva ac generator.

The unit is composed of a compressor assembly, power turbine assembly, and an accessory assembly. The APU

ignition and electrical controls are energized by 28-Vdc power provided by the isolated dc bus through the APU

CONTROL circuit breaker on the pilot side circuit breaker panel.

2.19.1 Compressor Assembly

The APU uses a two-stage, centrifugal-type compressor. When the compressor is operating at full speed, part of the

compressed air is discharged into the power turbine to support combustion and the remainder is available as

pneumatic power.

2.19.2 Power Turbine Assembly

The power turbine assembly drives the compressor and the APU accessories. The assembly consists of a turbine

section and a combustor . Fuel is injected into the combustion chamber, mixed with air, and burned. The combustion

gases are directed against the turbine wheel, which supplies rotary power to drive the compressor and accessory

assemblies. After being used to turn the turbine wheel, the combustion gases pass out the exhaust.

2.19.3 Accessory Assembly

The accessory assembly of the APU consists of a starter motor, oil and fuel pumps, an oil generator cooler fan,

tachometer generator, mounting pad for shaft powered accessories (APU generator), and a governor. The accessory

group, with the exception of the starter motor, is powered through a reduction gear train directly coupled to the

compressor drive shaft. The starter motor is coupled to the reduction gear train through a spring-loaded clutch.

2.19.4 APU Oil System

The APU oil circulation system provides lubrication for all gears and shaft bearings. Oil from a reservoir in theAPU

compartment is delivered by a gear-type pump through an oil filter to the various lubrication points. A relief valve

in the system maintains the desired pressure. Oil is removed from the unit by a dual scavenge pump and returned to

the reservoir, either through the oil cooler or, if oil temperature is below 27 _C (80 _F), through theoil coolerbypass

valve. An oil drain line is connected to the accessory section to eliminate the possibility of oil accumulation after

the APU is stopped. Oil used in this unit must conform to the specification and grade listed in the servicing diagram

(see Figure 3-1).

2.19.5 APU Fuel System

Fuel is gravity fed from the No. 2 main fuel tank through a motor-operated shutoff valve located in the No. 2 dry bay.

The valve is open when the APU CONTROL switch is in the START position and is held open when the switch is

released to RUN and the START light is illuminated. The valve is closed when the switch is in the STOP position

or when the APU fire emergency control handle is pulled. A fuel strainer is located in line behind the APU

compartment. During the starting cycle, when the oil pressure in the APU oil system reaches approximately 4 psi,

the fuel and ignition circuits are energized through a switch actuated by oil pressure.

ORIGINAL

2-152

01-75GAL-1

2.19.6 APU Control System

The operation of the APU is governor-controlled to maintain a nearly constant speed of approximately 100-percent

rpm under varying load conditions. The speed-sensing governor, powered by the accessory gear train, controls the

unit byregulating fuelflow intothecombustionchamber. Anoverspeed switchdeenergizes thecontrol circuit,which

shuts the unit down.

2.19.7 APU Controls

All APU controls are located on the APU control panel on the overhead control panel (see Figure 2-77). The APU

controls are energized by 28-Vdc power from the isolated dc bus through the APU CONTROL circuit breaker on

the pilot side circuit breaker panel.

Athree-position(STOP,RUN,START)toggleswitchcontrolstheoperationoftheAPU.WhentheAPUCONTROL

switch is placed in the RUN or START position, power is supplied to open the APU inlet door. The inlet door is

powered through contacts of the auxiliary touchdown relay. The door opens approximately 35_ on the ground and

15_ in flight.

Ensure that the APU CONTROL circuit breaker on the pilot side circuit

breaker panel is open before working around the APU air intake door.

Failure to comply could result in injury to personnel because of the action

of the APU door.

Figure 2-77. Auxiliary Power Unit Control Panel

ORIGINAL

2-154

01-75GAL-1

Note

The APU door can be opened on the ground to run the APU when the door

actuator has failed by removing the access panel, removing the retaining

bolt on the actuator, sliding the actuator forward to open the door, and

replacing the bolt to retain the door in the open position. To bypass the

actuator limit switch, disconnect the actuator connector plug and attach it

to the dummy receptacle adjacent to the actuator.

Holding the APU CONTROL switch in the spring-loaded START position energizes the start and holding relays,

which opens the wing tank APU fuel shutoff valve and energizes the starter. The start relay remains energized until

the circuit is broken by the 35-percent speed switch or by moving theAPU CONTROL switch to the STOP position.

When the switch is released, it moves to the RUN position. In this position, all APU circuits are energized to the

various automatic controls. These oil-pressure and speed-sensitive switches control their respective circuits to

accomplish starting and running of the APU. When the switch is in the STOP position, all circuits are deenergized.

When the APU CONTROL switch is placed in the STOP position, the overspeed test solenoid breaks the contacts

on the 110-percent speed switch and shuts down the APU. If the 110-percent speed switch is inoperative, the APU

will not shut down and thefireemergency control handlemust bepulled todeenergizetheholding circuitand toclose

the APU fuel shutoff valve in the No. 2 dry bay. When the APU CONTROL switch is placed in the STOP position

or the fire emergency control handle is pulled, the APU inlet door is energized to close after the APU speed has

decreased to approximately 18-percent rpm. This action is provided by an oil pressure switch that actuates at

approximately 20 psi and is done to prevent collapse of the inlet duct because of negative pressure when the door

closes.

2.19.7.1 BLEED AIR VALVE Switch

A BLEED AIR VALVE switch is located on the APU control panel. After the compressor reaches 95-percent rpm,

this two-position (OPEN, CLOSE) toggle switch controls the normally closed, solenoid-operated bleed-air valve.

With the valve closed, air is supplied to the power turbine combustion chamber only. With the valve open, air is

supplied to both the combustion chamber and the bleed-air manifold of the aircraft. Applying a bleed-air load to the

compressor before it reaches operating speed is prevented by the 95-percent speed switch, which completes the circuit

to the BLEED AIR VALVE switch only after operating speed is reached.

2.19.7.2 Fire Emergency Control Handle

The APU fire emergency control handle on the overhead control panel provides for emergency shutdown of the APU.

This handle, when pulled, energizes themotor-operated fuel shutoff valveclosed and energizes theAPU doorclosed

after APU speed has decreased to approximately 18-percent rpm. It also interrupts control power to the APU, causing

it to shut down. The fire extinguisher system control valves are positioned, and the extinguishing AGENT

DISCHARGE switch is armed.

2.19.8 APU Indicators

The indicators for the APU are located on the APU control panel, which is part of the overhead control panel.

2.19.8.1 START Light

A press-to-test START light is located on the APU control panel. This press-to-test light illuminates to indicate that

the starter circuit is energized and engaged with the APU drive train. The light remains illuminated until the

compressor reaches approximately 35-percent rpm, at which time a centrifugal switch deenergizes both the starter

and the start light.

2-155

ORIGINAL

01-75GAL-1

2.19.8.2 APU ON SPEED Light

A press-to-test, ON SPEED light, located on the APU control panel, is energized through the 95-percent speed switch

and indicates that the APU has reached or is maintaining operating speed.

2.19.8.3 APU DOOR OPEN Light

An APU DOOR OPEN light is located on the APU control panel. This press-to-test light illuminates when the APU

intake door is not closed.

2.19.8.4 APU Tachometer

The tachometer located on the APU control panel indicates APU speed in percent of normal APU rpm. Normal rpm

(100 percent) equals 42,000 rpm. A vernier dial on each indicator makes it possible to read to the nearest percentage.

The tachometer system has an APU-driven tachometer generator and is not dependent upon the aircraft electrical

system for operation.

2.19.8.5 Exhaust Gas Temperature Indicator

The EGT indicator is located on the APU control panel. The indicator is graduated from 0 to 1,000 _C with

20_ increments. The EGT system is a thermocouple thermometer that is not dependent upon the aircraft electrical

system for operation.

2.20

INSTRUMENTS

2.20.1 Standby Attitude Indicator

A standby attitude indicator is provided on the pilot instrument panel (see Figure 2-78). The indicator (see Figure

2-81) contains an electrically driven vertical gyro that maintains vertical orientation through use of a mechanical

erection system. The erection system incorporates automatic erection cutoff when subjected to fore-aft or lateral

accelerations exceeding approximately 0.16g. The display of attitude information is accomplished by mechanical

coupling from the vertical gyro to the display drum. A caging pitch trim knob is provided on the lower right corner

of the indicator. A warning (OFF) flag appears when power is removed from the indicator. The warning flag drives

out of view on application of power and appears immediately when power is removed. A switch actuated by the

caging knob causes the warning flag to appear when the caging knob is pulled. The gyro wheel speed and the unique

nature of the erection mechanism combine to provide a minimum of 9 minutes of attitude information after a loss

of power to the indicator. The warning flag being in view during this time period does not invalidate the attitude

information. Power is supplied to the standby attitude indicator from the isolated dc bus through the STANDBY

ATTITUDE INDICATOR circuit breaker on the pilot side circuit breaker panel.

Caging the indicator by pulling the caging/pitch trim knob to its fully extended position orients the gyro spin axis

to the position of thecase. Ifthe indicatorcase is misoriented during caging operation, the spin axis will not becaged

to true vertical and will require time to erect to true vertical. This erection rate is a nominal 2.5 degrees per minute.

Caging of the attitude indicator after power is off during shutdown is recommended.

Note

Pulling the caging/pitch trim knob to the fully extended position, rotating

clockwise, and releasing to a detent position locks the gimbals of the gyro.

This position may be used during turn-on procedure to eliminate nutations

of the drum. To unlock the gimbals (uncage gyro), pull the caging/pitch

trim knob from the detent to fully extended, rotate counterclockwise to

align the miniature aircraft with the horizon line, and slowly allow the knob

to return to its in position. An increase in audible noise may be evident

when operating in the caged position.

ORIGINAL

2-156

01-75GAL-1

2.20.1.1 Operating Procedures

2.20.1.1.1 Startup and Checkout

To place the indicator in operation, perform the following:

1. Adjust lighting via the pilot’s instrument lighting control on the pilot’s side shelf.

2. Uncagethegyro by pulling thecaging/pitch trim knob out, rotating counterclockwise, and gradually releasing

the knob to the full “in” position. Observe that the warning flag is driven from view and the indication is

completely stabilized within 3 minutes.

3. Adjust the caging knob clockwise or counterclockwise to obtain the desired pitch axis presentation.

Note

If the desired pitch trim adjustment cannot be obtained, the indicator may

be installed improperly. Do not recage the indicator to correct pitch attitude

misalignment.

2.20.1.1.2 In-Flight

Theindicatordoesnotnormallyrequireadjustmentduringflight.However,intheeventerrors arecaused byextended

steep maneuvers, the aircraft should be brought to level flight and the indicator should be momentarily caged.

Note

Cage and lock the operating attitude indicator only when the aircraft is at

a complete stop. Never cage and lock the operating attitude indicator while

the aircraft is in motion (i.e., flying, taxiing, towing).

2.20.1.1.3 Postflight

To power down the standby attitude indicator, perform the following:

1. Cage the indicator by pulling the caging/pitch trim knob to the fully extended position, rotating clockwise,

and releasing into the detent position.

2.20.2 Pitot-Static Instruments

Ram air (pitot) pressure and atmospheric (static) pressure to operate the vertical velocity, airspeed, and altimeter

indicatorsaresuppliedbythepitot-staticsystem(seeFigure2-80).Staticpressureissuppliedforthecabindifferential

pressure indicator, cabin pressure controller, cabin pressure safety valve, and the flight station air-conditioning unit

airflow regulator. Each aircraft is equipped with Rosemount pitot-static probes, two on each side of the aircraft. Each

probe provides one pitot pressure and two static pressure sources for a total of four systems. One system is dedicated

to the pilot instruments; one is for the copilot instruments; and one is for the navigator instruments, TAS computer,

airspeed sensor and cabin differential pressure gauge. The fourth system provides static pressure only to the FCS air

data control units. There are three static ports on the right side of the aircraft to provide atmospheric pressure for the

flight station air-conditioning and cabin pressure control systems.

2.20.2.1 Vertical Speed Indicator/Traffic and Resolution Advisory Display Indicators (VSI/TRA)

Two VSI/TRA indicators, one mounted on the pilot’s instrument panel and the other mounted on the copilot’s

instrument panel, display vertical speed data (current rate of climb/descent) and Traffic Alert and Collision

2-157

ORIGINAL

01-75GAL-1

Avoidance System (TCAS) information. As a vertical speed indicator, the VSI/TRA provides a standard display of

vertical speed in feet per minute with a range of ±6,000 feet per minute. Refer to paragraph 2.21.21.2 for TCAS

display and operating information. The pilot’s VSI/TRA receives 28 Vdc from the isolated dc bus through the PILOT

VSI/TRA circuit breaker on the copilot’s upper circuit breaker panel. The copilot’s VSI/TRA receives 28 Vdc from

the essential dc bus through the COPILOT VSI/TRA circuit breaker on the copilot’s upper circuit breaker panel.

2.20.2.2 Airspeed Indicators

The three airspeed indicators, one mounted on the pilot instrument panel (see Figure 2-78), one on the copilot

instrument panel (see Figure 2-79), and a true airspeed indicator on the navigator instrument panel (see Figure 1-7),

are instruments that use differential air pressure to determine airspeed. Each of the indicators is calibrated in knots.

The banded pointer (maximum allowable pointer) on the pilot and copilot indicator constantly indicates the

maximum recommended speed limit (V_H-1 with refueling pods off) for the respective aircraft altitude. The IAS

pointer reflects the aircraft airspeed. The IAS counter repeats the IAS pointerindication as a digital readout. An OFF

flag will be displayed in the IAS counter window until the aircraft speed exceeds 60 KIAS, at which time the flag

will be biased out of view. An IAS push-to-test button, located on the lower right of the instrument face, is provided

to test the IAS counter. Depressing and holding the pushbutton until the digital readout registers 300 indicates that

the IAS counter is operational. The press-to-test button is functional on the ground or in flight and does not affect

the indicator signal output when activated.

Note

A loss of ac power to the indicator will cause the IAS counter to fail and

the OFF flag to appear in the counter window. The IAS pointer will

continue to operate.

Figure 2-81. Standby Attitude Indicator

ORIGINAL

2-162

01-75GAL-1

The indicator also incorporates a bug-typepointer that can beset with an adjustableknob on the faceof theindicator.

The pointer provides the pilot with a means of referencing appropriate selected airspeeds for approach, climb, etc.

Thepilot and copilot airspeed indicators providesignals to therespectiveADI speed flag and speed deviation pointer

to display the difference between actual aircraft speed and manually set speed. Signals from the pilot airspeed

indicatorareusedbyairdatacontrolNo.1forIASholdmodeduringautopilot-coupled operation.Theairspeedsignal

circuits are powered by 26-Vac from the essential ac bus through the AIRSPEED-PILOT and COPILOT circuit

breakers on the pilot upper circuit breaker panel.

2.20.2.3 Altimeters

Thethreealtimeters,onemountedonthepilotinstrumentpanel(seeFigure 2-78),oneon thecopilot instrumentpanel

(see Figure 2-79), and one on the navigator instrument panel (see Figure 1-7), are barometric-type instruments

measuring variations in pressure by means of aneroid units. Each altimeter is calibrated in feet.

The pilot altimeter combines a conventional barometer altimeter and an altitude-reporting encoder in one

self-contained unit. A 10,000- and 1,000-foot digital counter indicator and a 100-foot drum indicator provide direct

digital output and readout ofaltitudeinincrements of100 feet,from -1,000to 50,000feet. Theencoderdigitaloutput

is referenced to 1,013 millibars and to 29.92 inches of mercury, and is not affected by changes in barometric setting.

A pointer repeats the indications of the 100-foot drum and serves both as a vernier for the drum and as a quick

indication of the rate and sense of altitude changes. Two methods may be used to read indicated altitude on the

counter-drum-pointer altimeter:

1. Read the digital counter indicator and the 100-foot drum indicator without reference to the pointer, as shown

by a direct digital readout in thousands and hundreds of feet.

2. Read the thousands of feet on the two digital counter indicators without referring to the drum indicator, and

then add the 100-foot pointer indication.

The self-contained servodriven encoder provides altitude data encoded in 100-foot increments for automatic

transmission when the air traffic control transponder is interrogated in mode C. In case of power loss to the

encoder-altimeter, an orange OFF flag will appear in a window in the upper portion of the display, indicating that

thepilotaltimeterisinoperative.Thepilotencoderispoweredby26-Vacfromtheessentialacbusthrough theALTM

ENCODER PILOT circuit breaker on the pilot upper circuit breaker panel.

The pilot altimeter is interconnected with the altitude alerter/preselect system to provide synchro outputs of

baro-corrected altitude and flag alarm signals. The altimeter setting is entered by use of a manually operated

barometric set knob in the lower right front of the instrument case. The altimeter setting appears on digital displays

at the right of the altitude display and has a range of settings from 950 to 1,050 millibars, and from 28.1 to 31.0 inches

of mercury. A press-to-test button, located on the lower left front of the instrument case, is provided to functionally

test the servomechanism. When actuated, the button causes a negative pointer offset indicating that the servo is

operating.

The copilot and navigator altimeters are read in the same manner as the pilot altimeter. However, these altimeters

do not contain an altitude reporting encoder and, hence, no OFF flag. The altimeters also are not equipped with the

functional test button. The copilot and navigator altimeters have internal vibrators that operate continuously

whenever aircraft dc power is turned on. The vibrator minimizes internal mechanical friction, enabling the instrument

to provide a smoother display during changing altitude conditions. Should vibrator failure occur, the altimeter will

continue to function pneumatically, but a less smooth movement of the instrument display will be evident with

changes in altitude. The vibrators are powered by 28-Vdc power from the essential dc bus through the ALTIMETER

VIBRATOR CO-PILOT & NAV dc circuit breaker on the copilot upper circuit breaker panel.

2-163

ORIGINAL

01-75GAL-1

If the altimeter internal vibrator is inoperative because of either internal

failure or dc power failure, the 100-foot pointer may hang up momentarily

when passing through 0 (12-o’clock position). Ifthevibratorhas failed, the

100-foot pointer hangup can be minimized by tapping the case of the

altimeter. Pilots should be especially watchful for this failure when their

minimum approach altitude lies within the 800- to 1,000-foot part of the

scale (1,800 to 2,000 feet, 2,800 to 3,000 feet, etc.), and should use any

appropriate altitude backup information available.

2.20.3 Miscellaneous Instruments

2.20.3.1 Free-Air Temperature Indicators

The free-air temperature indicator, located on the copilot instrument panel (see Figure 2-79), indicates ambient,

outsideairtemperature. This temperaturemust becorrected forcompressibility fortrue airtemperature during flight.

Theindicatoriselectricallyconnectedtoaresistancebulbmountedonthesideoftheaircraft.Thefree-airtemperature

indicator receives 28-Vdc from the TEMP IND FREE AIR circuit breaker on the copilot lower circuit breaker panel.

2.20.4 Magnetic Compass

Amagneticcompass(seeFigure2-78)ismountedonthepilotinstrumentpanel.Itis astandard floating-cardcompass

that indicates the direction that the aircraft is headed with respect to magnetic north.

Note

The magnetic compass is intended as a standby compass and should not be

used except in case of emergency. For the most reliable operation of the

magnetic compass, the pitot heat should be turned on and the HSI set to

correspond with the aircraft heading.

2.20.4.1 Accelerometer

An accelerometer (see Figure 2-78) on the pilot instrument panel gives instantaneous readings and maximum positive

and negative readings of the g forces exerted on the aircraft. The gauge is calibrated from +4 g to -2 g. The maximum

indication needles will remain at their highest readings until the push-to-set button on the gauge case is pushed, then

they both will return to +1g and immediately register maximum value until again reset.

2.20.4.2 Clocks

Three clocks are mounted in the aircraft, one each on the pilot, copilot , and navigator instrument panels (see Figures

2-78, 2-79, and 1-7).

2.20.4.3 Electronic Clocks (Aircraft 165313 and Up)

Three electronic six-digit liquid-crystal display clocks are installed. Two are installed on the main instrument panel,

one for the pilot and one for the copilot (see Figure 2-78 and 2-79). An additional clock is installed at the navigator

station. Each clock has an internal battery that allows continuous timekeeping when 28-Vdc power is not applied.

The clocks have two operating modes: elapsed time (ET) and clock time (C). To select between ET and C, press the

SEL pushbutton. Power is supplied to the clocks from the isolated dc bus through the CLOCKS circuit breaker on

the pilot side circuit breaker panel.

ORIGINAL

2-164

01-75GAL-1

Self-Test:

1. During the first 5 seconds of operation, the clocks initiate a self-test that illuminates all of the segments. After

completion of the self-test, the clocks start up in C mode.

Elapsed-time operation:

2. If ET operating mode is not indicated, press SEL pushbutton to select ET operating.

3. Press CTRL pushbutton to start elapsed timer counting upward.

4. Press CTRL pushbutton a second time to stop elapsed time.

5. Press CTRL pushbutton a third time to zeroize elapsed timer.

6. Press CTRL pushbutton a fourth time to reset elapsed timer.

To set time in C mode:

7. Press SEL and CTRL pushbuttons simultaneously.

8. When the hour digits are flashing, press CTRL pushbutton to advance hours in one unit increments, or hold

to scroll to desired time.

9. To set minutes, press SEL pushbutton. When the minutes digits are flashing, press CTRL pushbutton to

advance hours in one unit increments, or hold to scroll to desired time.

10. To set seconds, press SEL pushbutton. When the seconds digits are flashing, press CTRL pushbutton to

advance hours in one unit increments, or hold to scroll to desired time.

11. Pressing SEL pushbutton while the seconds digits are flashing returns the clock to the C mode.

2.21

COMMUNICATION AND NAVIGATION EQUIPMENT

The communication and associated electronic equipment consists of radio and intercommunication equipment to

provide aircraft-to-aircraft communication, aircraft-to-ground communication, and intra-aircraft communication;

navigation sets for guidance; and radar sets for identification and warning (see Figure 2-82). For antenna locations,

see Figure 2-83. For equipment rack locations, see Figure 2-84. For an interface illustration of the heading/naviga-

tional reference component relationship, see Figure 2-85.

2.21.1 AN/AIC-18 or AN/AIC-25 Intercommunication System

The ICS permits voice communication among flight station and cargo compartment intercommunication stations.

TheAN/AIC-18 ICS is installed on aircraft priorto 165313, whiletheAN/AIC-25 ICS is installedon aircraft165313

and up. Voice communication is also possible with the groundcrew through an external interphone receptacle at the

left aft edge of the radome. Audio signals from the command and liaison radio receivers and transmitters can be

monitored at each of the flight station intercommunication stations. Audio signals from the VHF and UHF radio

receivers and transmitters (aircraft not modified by AFC-338) or VHF and V/UHF radio receivers and transmitters

(aircraft modified by AFC-338) can be monitored at each of the observer stations. Transmissions through all radio

transmitters can be accomplished at the flight station intercommunication stations. The observers can transmit only

on VHF 1, VHF 2, UHF 1, and UHF 2 (aircraft not modified by AFC-338) or VHF 1, VHF 2, V/UHF 1, and V/UHF

2-165

ORIGINAL

01-75GAL-1

(aircraft modified by AFC-338). Reception and transmission over the channels available at a particular station are

made possible by headset microphones at each intercommunication station. A three-position microphone/interphone

switch on both the pilot and copilot control wheels permits transmissions from these positions. A press-to-talk button

on the connector cords at all other intercommunication stations can be used to talk from these stations. A foot switch

is located at the navigator station and flight engineer station, and can be used as an alternateswitch to talk from these

stations. The auxiliary intercommunication control panel, installed in the forward cargo compartment, differs from

all other panels both in appearance and capability. It is equipped with two controls, a call button, and a volume knob

and is restricted to voice communication through the ICS. The forward cargo compartment interphone station at FS

245 bulkhead includes a microphone headset with a 75-foot extension cord stowed in a protective bag next to the

control panel. The ICS is operated from 28-Vdc power supplied from the isolated bus and essential dc bus through

the INTERPHONE circuit breakers on the copilot upper circuit breaker panel.

2.21.1.1 Intercommunication System Controls

2.21.1.1.1 Main Control Panel

Identical ICS control panels (see Figure 2-86) are installed on each pilot side shelf extension, on the overhead control

panel, on the navigator side panel/console, at the lower crew bunk, and above the pilot upper circuit breaker panel

for use by a flight instructor. A similar control panel is installed at each observer station.

The main control panels are equipped with similar push-pull switches for:

1. VHF 1 — AN/ARC-186 VHF command radio No. 1.

2. VHF 2 — AN/ARC-186 VHF command radio No. 2.

3. UHF 1 — AN/ARC-159 UHF command radio No. 1 (aircraft not modified by AFC-338).

4. V/UHF 1 — AN/ARC-210 V/UHF command radio (aircraft modified by AFC-338).

5. UHF 2 — AN/ARC-159 UHF Command Radio No. 2 (aircraft not modified by AFC-338).

6. V/UHF 2 — AN/ARC-210 V/UHF command radio (aircraft modified by AFC-338).

7. HF 1 — AN/ARC-190 HF command radio No. 1.

8. HF 2 — AN/ARC-190 HF command radio No. 2 (except HF 1 and HF 2, which are not available at observer

stations).

Push-pull switches are also provided on the control panel for interphone (INT) and hot mike (HOT MIC) operation;

the latter uses a listen switch and a talk switch. This panel also carries a master volume control, a call button, and

a rotary transmission selector switch.

2.21.1.1.2 Transmission Selector Switch

The transmission selector switch on the control panels in the flight station may be set to any one of seven positions,

by rotation from left to right: INT for interphone and PA system operation; VHF 1 and VHF 2 for transmission

through the two VHF command radios; UHF 1 and UHF 2 for transmission through the two UHF command radios;

and HF 1 and HF 2 for transmission through the two HF command radios. The observers can transmit only on INT,

VHF 1, VHF 2, UHF 1, and UHF 2 by placing their transmission selector switches in the desired position. On aircraft

modified by AFC-338, switch and panel nomenclature “UHF” has been replaced with “V/UHF.”

2.21.1.1.3 HOT MIC Switches

The hot mike (HOT MIC) mode of operation permits direct transmission to all other intercommunication stations

on the aircraft without operating the individual microphone switches.

ORIGINAL

2-166

01-75GAL-1

PRIMARY

LOCATION OF

TYPE

DESIGNATION

FUNCTION

OPERATOR

RANGE

CONTROLS

Intercommunication

AN/AIC-18A or

Crew intercommunication

Crewmembers

Crew stations within the

Pilot side shelf

equipment

AN/AIC-25

aircraft and external for

extension, copilot side

ground crew

shelf extension,

overhead control panel,

navigator station, left

forward bulkhead,

forward for each

paratroop exit door, at

top of pilot side circuit

breaker

Public address

AN/AIC-13

One-way communication

Crewmembers

Interior of aircraft and

Navigator station,

system

for cargo compartment

servicing personnel

auxiliary: pilot side shelf,

left forward bulkhead,

and at left-hand

paratroop door

VHF AM-FM radio

AN/ARC-186(V)

Two-way voice

Pilot and copilot

Line of sight

CDNUs

(2)

communication in the range

of 30 to 87.975 MHz FM to

151.975 MHz AM

UHF

AN/ARC-159(V)

Two-way voice

Pilot and copilot

Line of sight

UHF No. 2 copilot side

communication

communication in the range

shelf extension UHF No.

radio (2)

of 225 to 399.975 MHz

1 flight control pedestal

Encryption

KY-58

Secures voice

Pilot and copilot

—

UHF No. 2 copilot side

unit (4)

communication for VHF

shelf extension Others

and UHF radios

flight control pedestal

HF command radio

AN/ARC-190

Airborne voice

Pilot and copilot

100 to 2,500 miles on

Flight control pedestal

(2)

communication in the range

AM and greatly

(No. 1), copilot side shelf

of 2 to 30 MHz

extended range on SSB

extension (No. 2)

depending on operating

frequency, altitude, and

time of day

Encryption unit (2)

AN/USC-43

Secures voice

Pilot and copilot

—

Flight control pedestal,

communication for HF

copilot side shelf

radios

extension and navigator

station

Automatic direction

DF-206

For homing and bearing;

Pilot and copilot

20 to 200 miles

Flight control pedestal

finder (2)

also receives voice and

depending on power,

code signals

class of ground station,

frequency, and time of

day

VHF navigation

AN/ARN-126

Reception of all VHF/VOR,

Pilot and copilot

Localizer — 45 miles;

CDNUs

system (2)

tone localizer and voice

Omni — 200 miles

facilities; reception of

depending on altitude;

glideslope information and

Glideslope — 15 miles;

location marker symbols

Marker beacon — any

altitude

TACAN (2)

AN/ARN-118(V)

Receives bearing and

Pilot and copilot

Line of sight depending

CDNUs

distance information

on altitude

AN/ARN-139(V)

Figure 2-82. Table of Communications and Associated Electronic Equipment (Sheet 1 of 3)

2-167

ORIGINAL

01-75GAL-1

PRIMARY

LOCATION OF

TYPE

DESIGNATION

FUNCTION

OPERATOR

RANGE

CONTROLS

Receiving

AN/ARA-63A

Enables the aircraft to land

Pilot

20 miles

Flight control pedestal

decoding group

at airfields equipped with

an Aircraft Approach

Control System (AACS)

UHF direction

Homing on ARC-159

Pilot and copilot

Line of sight

Flight control pedestal

AN/ARA-50 1

finder

transmitter

DF-301E 2

UHF direction

AN/ARA-50

Homing on AN/ARC-210

Pilot and copilot

Line of sight

CDNUs

finder

DF-301E

transmitter

Encryption

KY-58

Secures voice

Pilot and copilot

VHF 1 and 2 control

units (4)

communications for VHF

pedestal; V/UHF 1

and V/UHF radios

control pilot side shelf;

V/UHF 2 control copilot’s

side shelf

V/UHF

AN/ARC-210

Two-way voice

Pilot and copilot

Line of sight

CDNUs

communication

radio

TCAS/IFF control

—

Control of TCAS and IFF

Pilot and copilot

—

Flight control pedestal

panel

functions

Global positioning

AN/ARN-151

Provides highly accurate

Pilot and copilot

—

CDNUs

system (GPS)

position, velocity, and time

Combined altitude

AN/APN-232(V)

Indicates absolute altitude

Pilot and copilot

0 to 50,000 feet altitude

Pilot and copilot

radar altimeter

of aircraft above the terrain

instrument panels

Ground proximity

Provides the pilot and copilot

Automatic

Any altitude

Flight control pedestal

warning system

with visual and aural

warnings of a flight condition

that could cause the aircraft

to come in close proximity to

the ground

Altitude alerter/

540-25100-004

Provides automatic visual

Pilot

0 to 50,000 feet altitude

Pilot glareshield

system

and aural signals during

approach to or departure

from a preselected altitude

IFF interrogator

AN/APX-76B

Interrogates properly

Line of sight

Navigator control panel

equipped receiver aircraft

Flight control

FCS 105

For automatic pilot or

Pilot and copilot

—

Flight control pedestal

system

instrument flying with INS,

and main instrument

VOR/ILS, or TACAN

panel

Inertial navigation

LTN-72 or

Provides accurate navigation

—

CDU No. 2 navigator

system

LN-100

and position determination

station; CDU No. 1 flight

information

control pedestal

True airspeed

Model 2504

Computes and displays

—

Navigator control panel

computer

true airspeed using

temperature, altitude, and

airspeed data

Multimode radar

AN/APS-133 (M)

Navigation and weather

Pilot

5 to 300 miles

Indicators: navigator

radar — displays IFF, INS,

station and pilot

ONS data and mapping

instrument panel; control

panels: navigator control

panel, pilot side

shelf/extension, and

pedestal

Figure 2-82. Table of Communications and Associated Electronic Equipment (Sheet 2)

ORIGINAL

2-168

01-75GAL-1

PRIMARY

LOCATION OF

TYPE

DESIGNATION

FUNCTION

OPERATOR

RANGE

CONTROLS

Compass

C-12

Detects and indicates

—

Navigator station

system (2)

relative heading referenced

to magnetic north

Emergency rescue

AN/PRT-5E

Distress signals

Crewmembers

1,000 miles

On transmitter

transmitter (4)

Notes

1. C-130T aircraft prior to 164993

4. Aircraft modified by AFC-338

2. C-130T aircraft 164993 and up

5. C-12 compass systems have been removed from 165378

3. Aircraft without AFC-338

Figure 2-82. Table of Communications and Associated Electronic Equipment (Sheet 3)

When the hot mike system is not being used, the HOT MIC switches should be pushed in to restore the

inter-communication system to normal functioning. The three-position (INPH, OFF, MIC) microphone switches on

the control wheels are spring loaded to the OFF position. With the switch held at the INPH position, the pilot can

transmit to all other intercommunication stations. If the switch is held to the MIC position, the pilot can transmit

through the communication transmitter selected on the transmission selector switch. Foot-controlled microphone

switches are located on the floor at the flight engineer and navigator stations.

2.21.1.1.4 CALL Button

A CALL button is located at the lower right corner of each of the crew station intercommunication control panels.

When the button is pressed, all radio receiver transmissions on the ICS are subdued 6 dB and all intercommunication

stations are put into direct contact with the calling station.

2.21.1.1.5 Intercommunication System Monitor Panel

Each crew station, except the left and right observer stations, is equipped with monitoring or mixer switches, enabling

all audio navigational systems to be connected to the ICS. The switches are of the push-pull type (pulled for ON,

pushed for OFF). They may be turned to regulate volume at the individual intercommunication station. The ICS

monitor panels (see Figure 2-85) serve to provide interconnection with the following communication and audio

navigational systems:

1. PA — AN/AIC-13 public address system

2. BCN — AN/ARN-126 marker beacon receiver.

3. ADF 1 — DF-206 automatic direction finder No. 1.

4. ADF 2 — DF-206 automatic direction finder No. 2.

5. VOR 1 — AN/ARN-126 VHF navigation receiver No. 1.

6. VOR 2 — AN/ARN-126 VHF navigation receiver No. 2.

7. TACAN 1 — AN/ARN-139(V) TACAN No. 1.

8. TACAN 2 — AN/ARN-118(V) TACAN No. 2.

9. AUXILIARY — Control panel.

2-169

ORIGINAL

01-75GAL-1

SYSTEM — COMPONENTS

LOCATION — RACK

Aircraft Approach Control System (AACS)

(AN/ARA-63A):

Pulse decoder

LH underdeck rack

Receiver

AACS receiver rack

Altimeter (CARA)

Receiver-transmitter

Electrical control and supply rack

Audible fire warning:

Amplifier

LH electronic rack

Generator

LH electronic rack

Relay

LH electronic rack

Automatic direction finder (ADF) (DF-206):

Receiver No. 1

ADF receiver rack

Receiver No. 2

ADF receiver rack

Compass (C-12):

Amplifier — Power supply No. 1

Compass equipment rack

Amplifier — Power supply No. 2

Compass equipment rack

Directional gyro No. 1

Compass equipment rack

Directional gyro No. 2

Compass equipment rack

Magnetic azimuth detector No. 1

LH wingtip

Magnetic azimuth detector No. 2

RH wingtip

Electrical:

Ac generator control panels (4)

Electrical control and supply rack

Ac generator voltage regulators (4)

Electrical control and supply rack

Ac instrument and engine fuel control inverter

RH underdeck rack

APU ac generator control panel

Electrical control and supply rack

APU ac generator voltage regulator

Electrical control and supply rack

APU generator control unit

Electrical control and supply rack

Copilot inverter

RH underdeck rack

Essential bus transformer-rectifier units (2)

Electrical control and supply rack

Generator control unit (4)

Electrical control and supply rack

Main bus transformer-rectifier units (2)

Electrical control and supply rack

Flight control systems (FCS 105):

Acceleration sensor

LH underdeck rack

Air data control No. 1

LH underdeck rack

Air data control No. 2

LH underdeck rack

Airspeed sensor

Navigator console

Autopilot amplifier

LH underdeck rack

Flight computer No. 1

LH underdeck rack

Flight computer No. 2

LH underdeck rack

Figure 2-84. Electrical and Electronic Equipment Installation (Sheet 2)

ORIGINAL

2-172

01-75GAL-1

SYSTEM — COMPONENTS

LOCATION — RACK

Mode coupler No. 1

LH underdeck rack

Mode coupler No. 2

LH underdeck rack

Turn rate sensor No. 1

Center underdeck rack

Turn rate sensor No. 2

Center underdeck rack

Vertical gyro No. 1

Underbunk rack

Vertical gyro No. 2

Underbunk rack

Yaw damper computer

LH underdeck rack

Fuel:

Fuel flow meter power supply

Fuel system equipment rack

Fuel quantity totalizer

Fuel system equipment rack

Relays (3)

Fuel system equipment rack

Global Positioning System (GPS):

Interface ship set

LH cargo equipment rack

Database couplers

LH cargo equipment rack

Signal data converter

LH cargo equipment rack

Ground proximity warning system:

Adapter

Underbunk rack

Air data computer

Navigator console

Computer

Navigator console

HF communication radio (ARC-190):

Antenna coupler No. 1 — HF

LH electronic rack

Antenna coupler No. 2 — HF

RH electronic rack

Coaxial resistor No. 1

LH electronic rack

Coaxial resistor No. 2

RH electronic rack

HF relay No. 1

LH electronic rack

HF relay No. 2

RH electronic rack

Interface boxes (if installed)

Equipment rack KY-58/75

Transceiver No. 1

Center underdeck rack

Transceiver No. 2

Center underdeck rack

IFF (AN/APX-100(V)):

Antenna selection relay

IFF rack

Mode 4 computer

LH underdeck rack

Receiver-transmitter

IFF rack

IFF interrogator (AN/APX-76B(V)):

Converter-synchronizer

IFF equipment rack

Mode 4 computer

LH equipment rack

Power relay

IFF receiver-transmitter rack

Receiver-transmitter

IFF receiver-transmitter rack

Transient suppressor

IFF receiver-transmitter rack

Inertial navigation (LTN-72 or LN-100):

Inertial nav unit No. 1

Electrical control and supply rack

Inertial nav unit No. 2

Electrical control and supply rack

INS battery (if installed)

Electrical control and supply rack

Figure 2-84. Electrical and Electronic Equipment Installation (Sheet 3)

2-173

ORIGINAL

01-75GAL-1

SYSTEM — COMPONENTS

LOCATION — RACK

INU fan No. 1

Electrical control and supply rack

INU fan No. 2

Electrical control and supply rack

INU fan power relay No. 1

Electrical control and supply rack

INU fan power relay No. 2

Electrical control and supply rack

INU fan warn relay No. 1

Electrical control and supply rack

INU fan warn relay No. 2

Electrical control and supply rack

Overheat detection system control unit

ODS equipment rack

Propeller synchrophaser unit

Electrical control and supply rack

Public address (AN/AIC-13):

Audio frequency amplifiers (3)

Center underdeck rack

Radar, multimode (AN/APS-133(M)):

Interface unit

RH underdeck rack

Receiver-transmitter

RH underdeck rack

Roll compensator

RH underdeck rack

Radar control switching relays

Underbunk rack

Secure voice system (KY-58):

Processors, UHF (2)

KY-58/75 equipment rack

Processors, VHF (2)

KY-58/75 equipment rack

Processors, V/UHF (2)

LH avionics equipment rack

TCAS/IFF

IFF transponder

IFF rack

TCAS receiver-transmitter

IFF rack

Mode 4 computer

IFF rack

Secure voice system (KY-75):

Keyers HF (2)

KY-58/75 equipment rack

Remote control units (RCU-11A/B):

(RCU-IIIA)

Navigator control panel

(RCU-111B)

Pedestal (No. 1) copilot side shelf extension (No. 2)

TACAN (AN/ARN-118)/(AN/ARN-139(V)):

Bearing adapter No. 1

LH underdeck rack

Digital to analog adapter No. 1

LH underdeck rack

Digital to analog adapter No. 2

LH underdeck rack

Receiver-transmitter No. 1

LH underdeck rack

Receiver-transmitter No. 2

LH underdeck rack

True airspeed computer (model 2504):

Computer

RH underdeck rack

Transducer

RH underdeck rack

Figure 2-84. Electrical and Electronic Equipment Installation (Sheet 4)

ORIGINAL

2-174

01-75GAL-1

SYSTEM — COMPONENTS

LOCATION — RACK

UHF communication radio (AN/ARC-159(V)):

Receiver/transmitter No. 1

Pedestal

Receiver/transmitter No. 2

Copilot’s side extension shelf

Antenna selector No. 1

Electrical control and supply rack

Antenna selector No. 2

LH underdeck rack

Antenna switch No. 1

Electrical control and supply rack

Antenna switch No. 2

LH underdeck rack

UHF low pass filter

Electrical control and supply rack

UHF direction finder (AN/ARA-50):

Amplifier relay

Electrical control and supply rack

UHF direction finder (DF-301E):

UHF/DF selector

LH underdeck rack

VHF AM-FM communication radio (AN/ARC-186(V)):

Receiver-transmitter No. 1

Underbunk rack

Receiver-transmitter No. 2

Underbunk rack

VHF Navigation system (AN/ARN-126):

Receiver No. 1

LH underdeck rack

Receiver No. 2

LH underdeck rack

V/UHF communication radio (AN/ARC-210):

Antenna converter No. 1

LH sidewall equipment rack

Antenna converter No. 2

RH sidewall equipment rack

Receiver-transmitter No. 1

LH cargo bay equipment rack

Receiver-transmitter No. 2

LH cargo bay equipment rack

Antenna selector coaxial switch No. 1

LH cargo bay equipment rack

Antenna selector coaxial switch No. 2

LH cargo bay equipment rack

Filter No. 1

LH cargo bay equipment rack

Filter No. 2

LH cargo bay equipment rack

Audio amplifier No. 1 (provisions)

LH cargo bay equipment rack

Audio amplifier No. 2 (provisions)

LH cargo bay equipment rack

Control unit No. 1

LH cargo bay equipment rack

Aircraft prior to 164993

Aircraft not modified by AFC-338

Aircraft 164993 and up

Aircraft modified by AFC-338

Aircraft prior to 165313

Aircraft 165313 and up

Figure 2-84. Electrical and Electronic Equipment Installation (Sheet 5)

2-175

ORIGINAL

01-75GAL-1

2.21.1.1.6 Auxiliary Control Panel

The ICES auxiliary control panel (see Figure 2-86) is equipped only with a CALL button and a VOLUME control.

This control panel is located at the forward bulkhead on the left side. The function of the call button on the auxiliary

panel is the same as for the CALL buttons on the crew station control panels; pressing the button puts the calling

station in direct communication with all other intercommunication stations and causes all radio receiver

transmissions on the ICS to be subdued 6 dB.

2.21.1.1.7 IFF Audio Monitor Panel

The IFF audio monitor panel (see Figure 2-86) located on the copilot side shelf extension provides a capability for

the pilot to monitor audio signals generated by either the AN/APX-100 IFF transponder or the AN/APX-76B IFF

interrogator.Tworotaryknobs, INTRGand XPNDR,areutilizedto selectand controlvolumefortheselectedsystem

audio signals. The audio signal will be heard as a short burst (buzz) in the 300- to 400-Hz range when monitoring

mode 4 interrogations.

2.21.1.2 Operation of the Intercommunication System (Crew Station Positions)

The procedure for operating the ICS from any of the crew positions or the crew bunk positions is as follows:

Note

Classified information will not be discussed on the ICS or on radios

operating in securemode whileother radios are transmitting in clearmode.

Conversely, no radio will transmit in clear mode while classified

information is being discussed on the ICS or another radio is transmitting

in secure mode.

1. To talk:

a. Set the transmission selector switch as desired.

b. Press the microphone switch (except for HOT MIC operation), and speak into the microphone.

2. To listen:

a. To listen to any radio communication receiver, pull the switch for the selected communication system; turn

the switch after pulling to regulate the volume to a desired level.

b. Push the switch in to disconnect the selected radio communication system.

2.21.1.3 Operation of the Intercommunication System (Auxiliary Stations)

To talk from the auxiliary intercommunication station, press the microphone switch on the microphone and speak

into the microphone. To listen, adjust the volume control to a comfortable level. Listening is possible only on the

ICS line.

Note

Classified information will not be discussed on the ICS or on radios

operating in securemode whileother radios are transmitting in clearmode.

Conversely, no radio will transmit in clear mode while classified

information is being discussed on the ICS or another radio is transmitting

in secure mode.

2.21.2 AN/AIC-13 Public Address System

The PA system provides one-way communication with the cargo area through seven speakers located in the cargo

compartment. The main control panel for the PA system is located at the navigator station, with auxiliary control

2-179

ORIGINAL

01-75GAL-1

panels located on the pilot side shelf extension, at the forward cargo compartment control panel, and on the left

observer panel forward of the left paratroop door. The PA system operates using 28-volt powerfrom themain dcbus

through a circuit breaker on the copilot upper circuit breaker panel.

2.21.2.1 Public Address System Controls

2.21.2.1.1 Main Control Panel

The main control of the PA system is from a control panel (see Figure 2-87) located at the navigator station.

Microphone connections to the PA system are made through all intercommunication control panels and through

microphoneconnectorsforusewith extensioncords onthecargocompartment auxiliarycontrol panelsat theforward

cargo compartment and left paratroop door positions. A power switch, a speaker selector switch, four mixer switches,

and a volume control switch constitute the controls on the main control panel.

2.21.2.1.2 Power Switch

The power switch has PWR ON and OFF positions. When the switch is placed in the PWR ON position, power is

supplied to all circuits of the system for normal operation.

2.21.2.1.3 Speaker Selector Switch

The four-position (ALL, FWD, AFT, JUMP) speaker selector switch selects the speaker or combination of speakers

to be operated. In the ALL position, all the speakers except the one located over the cargo ramp are in operation. In

the FWD position, only the speaker in the cargo compartment forward area is in operation. In theAFT position, only

the speaker over the cargo ramp is in operation. In the JUMP position, the two speakers adjacent to the paratroop exit

doors are in operation.

2.21.2.1.4 VOL Control Switch

The 11-position VOL control switch is used to adjust the audio output of the PA system. This switch is manually

controlled at the navigator station and electrically actuated by the PA GAIN control switch on the pilot side shelf

and auxiliary control panels.

2.21.2.1.5 Mixer Switches

Four mixer switches (ADF 1, ADF 2, UHF COMM, VHF COMM for aircraft not modified by AFC-338 or ADF-1,

ADF-2, V/UHF COMM, VHF COMM for aircraft modified by AFC-338) are located on the main control panel for

supplying radio receiver signals to the PA system. To connect a receiver to the system, place the mixer switch for

that receiver in the ON (up) position.

Note

The UHF COMM switch is for use with the UHF No. 1 system for aircraft

not modified by AFC-338. The V/UHF COMM switch is for use with the

V/UHF 1 system for aircraft modified by AFC-338.

2.21.2.1.6 Auxiliary Control Panels

After the PA system has been actuated and speaker selections made at the main control panel, the auxiliary control

panels (see Figure 2-87) can be used to operate the system. The PA SELECT switch on the pilot auxiliary control

panel and the PA ON-OFF switch on the cargo compartment auxiliary control panel are used to connect each station

to the PA system. Voice communication from the flight station intercommunication control positions is transmitted

to the PA system through the ICS. The audio output of the PA system is controlled by a PA GAIN switch on each

of the auxiliary control panels.

ORIGINAL

2-180

01-75GAL-1

2.21.2.1.7 PA SELECT Switch

The PA SELECT switch is a two-position (INTPH & PA, INTPH) switch located on the pilot side shelf extension

and is used to connect the ICS to the PA system. When the switch is placed in the INTPH position,

intercommunication conversation is confined to the interphone circuit. When the switch is placed in the INTPH &

PA position, intercommunication conversation is supplied to thePA system and radio receiversignals areeliminated

from the PA system.

2.21.2.1.8 PA Switch

This switch, installed on the cargo compartment auxiliary control panels, is a two-position (ON, OFF) momentary

switch used to connect that station to the PA system. Holding the PA switch in the ON position permits voice

communication through the speaker(s) selected on the main control panel. Activating this switch silences any radio

inputs that may be selected on the main control panel but does not silence microphone inputs from other PA stations

on the aircraft.

2.21.2.1.9 PA GAIN Switch

The PA GAIN switch is a three-position (INCREASE, OFF, DECREASE) momentary-type switch. When the switch

is held in the INCREASE position, the audio output of the PA system increases. When the switch is held in the

DECREASE position, the audio output of the system decreases. When the switch is released from either position,

a spring return moves it to the OFF (center) position. The manual control knob on the main control panel will be

physically rotated by an electric motor controlled by these switches.

2.21.2.2 Normal Operation of the Public Address System

Operate the PA system as follows:

1. Place the power switch in the ON position.

2. Place the speaker selector switch in the desired position.

3. If the PA system is to be operated from the flight station, place the PA SELECT switch in the INTPH & PA

position. When the PA system is keyed, radio receiver signals will be eliminated, and voice communication

from the flight station will be transmitted through the PA system and through the ICS. If the PA system is to

be operated from the cargo compartment forward auxiliary panel, or the observer station in the left rear of the

cargo compartment, hold the PA switch to the ON position.

4. Press the microphone button and talk.

5. If radio signals are to be heard over the PA system, place the desired mixer switch to the ON (up) position and

place the PA SELECT switch in the INTPH position.

6. To adjust the audio output of the system, rotate the VOL knob on the main control panel, or actuate the PA

GAIN switch on the auxiliary panel(s).

7. PA audio may be monitored at all flight station positions by turning on the PA switch on the respective

interphone panels.

8. When the PA system is operated from either cargo compartment position, monitor the speaker audio so the

volume can be adjusted to a suitable level.

To turn the PA system off:

9. Place the power switch in the OFF position.

2.21.3 Communication-Navigation Management System

The Communication-Navigation Management System (CNMS) provides control of the systems listed in Figure

2-88. System control and status monitoring is accomplished using Control Display Navigation Units (CDNUs).

2-183

ORIGINAL

01-75GAL-1

CAUTION

CDNU1 receives electrical power from the isolated DC bus and should be

turned on first to ensure that it serves as the BC controller in the event of

power loss or fluctuations to the essential DC bus.

SYSTEM

DESIGNATION

VHF/UHF Comm. No. 1

AN/ARC-210(V) (Aircraft with AFC-338)

VHF/UHF Comm. No. 2

AN/ARC-210(V) (Aircraft with AFC-338)

VHF1 Comm. No. 1

AN/ARC-186(V)

VHF2 Comm. No. 2

AN/ARC-186(V)

VHF Nav. No. 1

AN/ARN-126(V)

VHF Nav. No. 2

AN/ARN-126(V)

TACAN No. 1

AN/ARN-139(V)

TACAN No. 2

AN/ARN-118(V)

Satellite Signals Navigation Set (GPS)

AN/ARN-151(V)

Figure 2-88. CNMS Controlled Systems

2.21.3.1 Control Display Navigation Unit (CDNU)

CNMS control and status monitoring are accomplished using the Control Display Navigation Units (CDNUs).

CDNUs are installed on the flight control pedestal, the copilot side panel and navigator station (see Figures 2-89 and

2-90). The pilot’s CDNU is designated as CDNU1, the copilot’s is CDNU2, and the navigator’s is CDNU3. Any

single CDNU has all the required resources to completely operate the CNMS and associated systems. Each CDNU

operates as either a bus controller (BC) or a remote terminal/backup bus controller (RT/BBC). The CDNU that

receives electrical power first will function as the BC CDNU. The BC CDNU performs navigation computations,

builds page displays, communicates with associated equipment, and performs all other computations required to

support CNMS and associated systems operations. The RT/BBC CDNUs serve as spare BCs which process

keystroke inputs, display pages built by the BC CDNU, and perform continuous built-in-testing (BIT) with any free

processor time. CDNU 1 receives 28 Vdc power from the isolated DC bus through the PILOTS CDNU circuit breaker

on the pilot’s upper circuit breaker panel. CDNUs 2 and 3 receive 28 Vdc power from the essential DC bus through

the COPILOTS CDNU and NAV CDNU circuit breakers on the pilot’s upper circuit breaker panel.

2.21.3.2 CDNU Display

The CDNU display has 8 lines of 22 characters each (see Figure 2-90). Lines 1, 3, 5, and 7 are data lines with a line

select key on both the left and right side of the field. Line 2 is reserved for the page title and line 6 is reserved as an

annunciation line. Line 4 is an unreserved data line and line 8 is the scratchpad for displaying keypad entries.

ORIGINAL

2-184

01-75GAL-1

2.21.3.2.1 Scratchpad

The scratchpad is used to hold all keystrokes prior to executing theinput. Incorrect scratchpad entries may becleared

using the CLR key. A single press of the CLR key clears the last character entered and a second press (without

additional intervening keystrokes) will clear the entire scratchpad. Holding the CLR key begins to repeat deletion

of one character at a time. The scratchpad is cleared automatically when the system accepts valid data inputs.

2.21.3.3 CDNU Controls

CDNU data entry operations are performed with a full alphanumeric keypad, arrow keys, function keys and eight

line select keys (see Figure 2-90). Each CDNU provides simultaneous and independent operation; meaning that one

CDNU can be used to display systems status while another is being used to edit the flight plan. The only exception

to the simultaneous and independent operation involves system annunciations on Line

6 of all CDNUs

simultaneously. Symbolic aids are used to indicate what entries can be made, what functions are on or engaged, and

what selections are possible. Figure 2-91 lists several symbol aids and their definition.

CDNU SYMBOL

DEFINITION

Pushing line select key accessed different page

←→

Pushing line select key selects item or enables mode

→←

Indicates function is engaged or enabled

Alternate selection among modes

Check, as in check status for equipment failures

---

Indicates no computed data is available or power is off

Indicates data entry from scratchpad is possible or required

[

]

Indicates vertical page or line scrolling is possible

Indicates lateral page scrolling is possible

Indicates lateral and vertical page scrolling is possible

Figure 2-91. CDNU Symbology

2.21.3.3.1 OFF/ON

The rotary knob on the lower right side of the CDNU display screen turns CDNU power on and off.

ORIGINAL

2-188

01-75GAL-1

2.21.3.3.2 BRT

The rotary knob on the lower left side of the CDNU display controls the intensity and brightness of the CDNU display.

2.21.3.3.3 Line Select Keys

These keys can be used to access lower level pages, toggle modes of a function, or enter data in an associated field.

For certain functions, line selects may be used both for selecting a mode and for input of numeric values used by the

mode. If the scratchpad is blank, pressing the line select toggles the mode. If the scratchpad is not blank, pressing

thelineselect will input numericdata(ifvalid)andwill nottogglethemode. Whenundefined lineselects arepressed,

no operation is performed.

2.21.3.3.4 Alphabetic, Numeric and Punctuation Keys

These keys allow for data entry into the scratchpad. The period (.) and slash (/) keys are used to enter navigational

data. The dash (-) key can be used to delete input data or to enter negative valued data.

2.21.3.3.5 Special Function Keys

Keys F1 through F7 are special function keys. The functions of each key are shown in Figures 2-92 and 2-93.

2.21.3.3.6 Direct Access Keys

The direct access keys consist of RNAV (area navigation), STAT (system status), IDX (index), FPLN (flight plan),

PROG (progress), DIR (direct to), MENU (menu), and MARK (current position to scratchpad). The direct access

keys provide access to various functional CDNU pages as shown in Figures 2-92 and 2-94.

1. INX — Index pages provide access to a variety of Utility pages (see Figure 2-92 and paragraph 2.21.3.4) and

support functions required to operate and test system hardware.

2-189

ORIGINAL

01-75GAL-1

2. FPLN — The Flight Plan page is the center of the navigation function, providing access not only to the flight

plan itself, but also to the associated functions in support of flight plan maintenance and execution. This key

provides for display of the flight plan on CDNU. Past and present waypoint data may be accessed using the

scroll keys (refer to paragraph 2.21.4.4.3).

3. DIR — Pressing the DIR key causes the CDNU to display flight plan waypoints on the direct to [ ] page.

Waypoints may be accessed via the scroll page and selected for direct to navigation with the corresponding

line select key (refer to paragraph 2.21.4.4.6).

4. STAT — System Status pages provide information concerning the availability of various system equipment

(refer to paragraph 2.21.3.4).

5. PROG — Progress pages indicate where the aircraft is in relation to the desired flight plan and provide

guidance to acquire and execute the flight plan (refer to paragraph 2.21.4.4.5).

6. RNAV — The Area Navigation pages provide control and display or individual navigation sensors and how

they are integrated to form the navigational solution (refer to paragraph 2.21.4.4.4).

7. MARK— Themark keywrites theinstantaneous presentposition solutionofthesystem integratednavigation

solution into the scratchpad.

8. MENU — The Menu Page provides a list of the functions associated with the special function keys.

2.21.3.4 CDNU Utility Pages

The CDNU utility pages consist of the Power, Zeroize, Start, Systems status and Systems test pages. These pages

are accessed via the IDX and STAT direct access keys. They provide for overall operation and test of the CDNU and

CNMS associated equipment.

1. Power page — The Power page gives the operator control of system power for CNMS navigation and

communication equipment. Line select keys next to the system name are used to turn system power on and

off. A line box around the equipment name indicates the system is powered.

2. Zeroizepage— TheZeroizepagepermits selectivezeroing ofnon-volatilememory in theCDNU, MDL,GPS

receiver and AN/ARC-210(V) radio set. In addition to selective blanking, a single key commands a master

zeroize of all data stored in the system. All requests for zeroize require confirmation by pressing the associated

line select key a second time.

ORIGINAL

2-190

01-75GAL-1

Note

To avoid erasing the operational flight program and rendering the system

unusable, flight crew personnel should not select ZEROIZE MDL (LS1)

or ZEROIZE ALL (LS8).

3. Systems Status Pages — The CDNU monitors the status of each CNMS component and executes continuous

built-in test (CBIT) software which evaluates those items that can be assessed during normal operations with

thehardwareon-line. This occurs without any required operator action and theresults areavailable fordisplay

at all times. When a failure is detected in the CBIT routine, a STATUS annunciation appears on the line

6 annunciation line. A XXXX STATUS message is displayed in the scratchpad if operation is attempted

which cannot be performed due to conditions causing the

STATUS annunciation. Outputs from a

component indicating a failed status are not used for computations or display. Results from CBIT routines are

compiled and reported on the Systems Status Pages. Additionally, detailed status pages are available for most

components and are indicated by outward pointing arrows on the status pages.

ORIGINAL

2-196

01-75GAL-1

4. System Test Pages — The SYS TEST page provides the capability to BIT test the CDNU, MDL, GPS receiver,

ISS and CDNU units. When the line select key is pressed on the SYS TEST page, the CDNU screen will either

go to the detailed test page of the associated component or perform the BIT test of that component. Systems

with detailed test pages have outward pointing arrows on the SYS TEST page. Tests for systems with inward

pointing arrows are initiated when the associated line select is pressed.

5. Comm Page — The comm page controls tuning and other function settings for the VHF 1 and VHF 2

communication systems and also V/U-1 and V/U-2 communication systems for ARC-210 equipped aircraft.

The comm page is accessed via the F3 key or via the index page. Tuning is accomplished by entering the

appropriate frequency in the scratchpad and then pressing the line select key next to the corresponding radio.

Pressing the line select key with no frequency in the scratchpad (blank scratchpad) will access the detailed page

for the corresponding radio. Quick tuning can be accomplished by entering the frequency in the scratchpad

and pressing F1 for VHF 1/VU-1 or F2 for VHF 2/VU-2. Returning to the previously selected frequency may

be accomplished by tuning 0.

2-197

ORIGINAL

01-75GAL-1

6. Nav Page — The NAV page controls tuning and basic function settings for the VOR-1, VOR-2, TACAN-1

and TACAN-2 navigation systems. The NAV page is accessed via the F6 key or via the index page. Tuning

is accomplished by entering the appropriate channel/frequency in the scratchpad and then pressing the

corresponding left-side line select key. Pressing the line select key with no channel or frequency in the

scratchpad (blank scratchpad) will access the detailed page for the corresponding VOR or TACAN. Quick

tuning for the TACANs can be accomplished by entering the channel in the scratchpad and pressing F4 for

TACAN-1 or F5 for TACAN-2. Returning to the previously selected frequency may be accomplished by

tuning 0. Additionally, the operator can also pair TAC-1 to VOR-1 and TAC-2 to VOR-2 for simultaneous

tuning to paired NAVAID frequencies. Paired operation is enabled using the right-side line select key next

to the respective TACAN. The letters “PR” on the CDNU display indicates the paired function is enabled and

the paired TACAN channel will automatically be tuned to correspond with the VOR frequency; “MN”

indicates that the paired function is not enabled.

2.21.3.5 Interface Shipsets

Two interface shipsets (ISS) are incorporated with the CNMS to convert analog and discrete signals to the digital

format required by the CDNU. The ISS units receive 26 Vac power through the ISS circuit breaker on the pilot’s upper

circuit breaker panel. ISS1 receives 28 Vdc power from the isolated DC bus through the ISS NO. 1 circuit breaker

and ISS2 receives 28 Vdc power from the essential DC bus through the ISS NO. 2 circuit breaker.

2.21.3.6 Signal Data Converter

The Signal Data Converter (SDC), CV-4138/A, converts serial digital outputs from the CDNU to analog signals used

to driveflight instruments, displays and annunciators. The SDC is located in theleft-hand cargo bay equipment rack.

The SDC receives 115 V and 26 Vac power from the essential AC bus through the SDC circuit breakers on the pilot’s

upper circuit breaker panel.

2.21.4 AN/ARN-151(V) Satellite Signals Navigation Set (Global Positioning System)

The AN/ARN-151 Satellite Signals Navigation Set is a worldwide all-weather navigation aid that receives and

processes navigation information from NAVSTAR GPS satellites. GPS is a space-based radio positioning system

that provides its users with highly accurate position, velocity and time data. This service is provided globally,

ORIGINAL

2-198

01-75GAL-1

continuously, and under all weather conditions to users. GPS receivers operate passively, thus allowing an unlimited

number of simultaneous users. The GPS has features that can deny accurate service to unauthorized users, prevent

spoofing and reduce receiver susceptibility to jamming.

Use of GPS for approaches or as a primary means of instrument navigation

is not authorized at this time. GPS is only authorized as an aid to visual

navigation (VFR).

GPS provides the most useful and accurate navigation solution available, but operators are cautioned not to be

over-confident of the system. Appropriate cross-checking of GPS with other forms of navigation (INS, VOR,

TACAN and visual methods) should be employed to ensure safety and mission accomplishment.

2.21.4.1 Theory of Operation

The GPS comprises three major segments: Space, Control and User. The Space segment consists of a constellation

ofGPSsatellitesinorbit aroundtheEarth.Each satellitebroadcasts radio-frequencyranging codesand anavigational

data message. The Control segment consists of a Master Control Station (MCS) and a number of monitor stations

located around the world. The MCS tracks, monitors and manages the satellite constellation and updates the

navigational data messages. The User segment consists of various navigational receivers specifically designed to

receive, decode and process the GPS satellite-ranging codes and navigational data messages.

CAUTION

Standard military GPS systems do not provide a navigation integrity

function which would monitor and cross check the validity of satellite

transmitters and GPS receivers.

The ranging codes broadcast by the satellites enable a GPS receiver to measure the transit time of the signals and

thereby determine the range between a satellite and the user. The navigation data message enables a receiver to

calculate the position of each satellite at the time of transmission of the signal. Four satellites are generally required

to be simultaneously “in-view” of the receiver for three-dimensional (3-D) positioning purposes. Less than four

satellites can be used if the user altitude or system time is precisely known.

2.21.4.2 Levels of Service

Two levels of navigation are provided by the GPS, the Precise Positioning Service (PPS) and the Standard

Positioning Service (SPS). The PPS is a highly accurate positioning, velocity and timing service that is made

available only to authorized users. The SPS is a less accurate positioning and timing service that is available to all

GPS users.

2.21.4.2.1 Precise Positioning Service (PPS)

The PPS provides 16-meter Spherical Error Probable (SEP) positioning accuracy and 100 nanosecond Universal

Coordinated Time (UTC) time transfer accuracy to authorized users. The PPS is primarily intended for military

purposes. Authorization to use the PPS is determined by the Department of Defense (DoD), based on U.S. defense

requirements and international commitments.

2-199

ORIGINAL

01-75GAL-1

Access to the PPS is controlled by two features using cryptographic techniques. A Selective Availability (S/A) feature

(when turned on) is used to reduce the accuracy of the GPS position, velocity and time data available to unauthorized

users. S/A operates by introducing controlled errors into the satellite signals. System accuracy degradations can be

increased during crises or war. An Anti-Spoofing (A-S) feature is invoked at random times without warning by the

U.S. to negate potential spoofing (hostile information) of PPS signals. Encryption keys and techniques are provided

toPPSusers thatallow themto removetheeffectsofS/Aand A-Sand therebyattain themaximum availableaccuracy

of GPS. PPS-capable receivers that do not have the proper encryption keys installed will be subject to the accuracy

degradations of S/A and potential spoofing or jamming of GPS signals.

CAUTION

D Operate GPS receivers in keyed mode for greater position, velocity and

time accuracy as well as improved anti-spoofing and anti-jam capability.

Failure to do so may lead to gross navigational errors.

D Aircrews should be aware that GPS is susceptible to intentional and

unintentional interference and loss of GPS timing can affect HaveQuick

operation.

2.21.4.2.2 Standard Positioning Service (SPS)

The SPS provides 100-meter horizontal positioning accuracy to any GPS user during peacetime. SPS receivers can

also achieve approximately 337-nanosecond UTC time transfer accuracy. The SPS is primarily intended for civilian

purposes, although it has many peacetime military uses as well. The SPS horizontal accuracy specification includes

the peacetime degradation of S/A that is the dominant SPS error source.

2.21.4.3 AN/ARN-151(V) System Components

The AN/ARN-151 Satellite Signals Navigation Set consists of the following primary components:

1. GPS Receiver.

2. Mission Data Loader.

3. GPS Fill Panel.

4. Control Display Navigation Unit (CDNU).

5. Main Annunciator Panel.

2.21.4.3.1 GPS Receiver

The R-2332/AR GPS receiver is the receiver/processor for the GPS. The receiver decodes satellite signals and

provides position coordinates, altitude, speed and time data to aircraft systems. The GPS receiver is located in the

LH Cargo Bay Equipment rack. The system receives 115 Vac power from the essential AC bus through the GPS

RCVR circuit breaker and 28 Vdc power from the essential DC bus through the FLT DATA SW PNL and DATA

LOADER circuit breakers located on the pilot’s upper circuit breaker panel. Three C-cell batteries comprise a battery

power supply that is located at the front of the receiver. The battery power supply ensures that critical data in memory

will not be lost when aircraft electrical power is secured. A time source and nuclear event detector is also powered

by the battery supply.

ORIGINAL

2-200

01-75GAL-1

2.21.4.3.2 Mission Data Loader

The AN/ASQ-215 Mission Data Loader is designed to provide bulk memory storage for military aircraft parameters,

waypoint database, and maintenance and avionics initialization data. It consists of an Interface Receptacle Unit (IRU)

located in the navigator’s sidewall equipment panel (see Figure 2-89) and a Data Transfer Module (DTM). The

removable DTM contains data that can be accessed by the CDNU. The MDL provides flight crews with the ability

to transfer flight plans, current GPS almanac data and a waypoint database directly to the CDNU.

2.21.4.3.3 GPS Fill Panel

The GPS Fill Panel enables loading of the GPS security codes from a KYK-13 Electronic Transfer Device (see Figure

2-89). These codes enable precision GPS navigation during times when S/A and/or A-S are activated. The fill panel

has two switches, one to initiate loading of security codes and one to zeroize existing codes. An LED status indicator

on the panel will illuminate briefly when the GPS receiver has accepted the security code. Reaction time is

approximately 4 to 5 seconds. Illumination indicates correct parity, but does not indicate that the code is correct. The

panel is located in the navigator’s sidewall equipment panel.

2.21.4.3.4 Control Display Navigation Unit (CDNU)

System control and status monitoring are accomplished using the Control Display Navigation Units (CDNUs). The

CDNU is the primary pilot-to-GPS interface. The CDNU performs all control, display, crew data entry, processing

and navigation computations for the GPS. CDNUs are installed on the flight control pedestal, the copilot side panel

and navigator station. Each CDNU is capable of operating the GPS. GPS information and status is displayed on

various CDNU screen pages. Refer to paragraph 2.21.3 for CDNU specifics.

2.21.4.3.5 Main Annunciator Panel

The main annunciator panel is located on the pilot’s instrument panel (see Figure 2-89). The annunciator panel has

four CNMS/GPS related indicator lights associated with the corresponding flight mode. Flight mode is set by the

operator on the CDNU expanded FPLN page. Indicator light and flight modes are as follows:

1. EN ROUTE light: Indicates the aircraft is in the enroute mode. With CDNU selected on the Navigation

Selector, two dots of deflection on the HSI equals 4.0 nm. A NAV invalid flag will appear on the HSI if GPS

Estimated Horizontal Error (EHE) exceeds 1,000 meters.

2. TERMINAL light: Indicates the aircraft is in the terminal mode. With CDNU selected on the Navigation

Selector, two dots of deflection on the HSI equals 1.0 nm. A NAV invalid flag will appear on the HSI if GPS

EHE exceeds 500 meters.

3. APPROACH light: Indicates the aircraft is in the approach mode. With CDNU selected on the Navigation

Selector, two dots of deflection on the HSI equals .3 nm. A NAV invalid flag will appear on the HSI if GPS

EHE exceeds 100 meters.

4. ALTER NAV light: Indicates the GPS is not being used as a navigation sensor and errors are no longer bounded

to the GPS navigation solution.

2.21.4.4 GPS and CDNU Navigation Operations

2.21.4.4.1 System Power

GPS system power is controlled via the CDNU power page. A rectangle box around the GPS component name

indicates the unit is ON.

2-201

ORIGINAL

01-75GAL-1

2.21.4.4.2 Loading GPS Secure Keys

GPS secure keys provide for secure (PPS) operation and are loaded at the GPS fill panel using the KYK-13.

Note

If keying GPS with power applied, ensure date and time are correct as

displayed on the GPS Start Page. Keys may not be loaded when GPS IBIT

testing is in progress.

1. Connect KYK-13 to FILL connector on GPS Fill Panel.

2. Set KYK-13 address switch to desired setting (1-6).

3. Set KYK-13 Mode switch to ON.

4. Momentarily hold GPS Fill Panel INITIATE/ZEROIZE switch to INITIATE (parity indicator flashes).

5. On GPS Fill Panel, verify LOAD/STATUS indicator flashes within 5 seconds to indicate successful load.

6. Set KYK-13 Mode switch to OFF.

7. Disconnect KYK-13 from GPS Fill Panel.

CAUTION

Failure to re-initialize the GPS after loading crypto keys may result in

significant navigation errors. After the GPS system has been loaded with

crypto keys and has acquired a figure of merit of one or two navigation

solution, access the power page of the control display navigation unit and

cycle the GPS power off and then back on or access the system test page

and perform an initiated built in test on the GPS system. Either of these two

procedures will re-initialize the GPS receiver.

2.21.4.4.3 Loading Flight Plans and Waypoints

The CDNU maintains several databases internally and on the MDL cartridge to support flight-planning operations.

The crew can create and maintain a flight plan of up to 50 geographic locations, stored in the order to be flown. The

flight plan is maintained through addition, modification, or deletion of waypoints. When waypoints are added in the

middle of the flight plan, succeeding waypoints are automatically moved down the list. Similarly, when waypoints

are deleted, the flight plan automatically eliminates all holes by moving waypoints up the list. The flight plan may

be selected and loaded from the MDL or created within the CDNU manually point-by-point.

A magnetic variation database is maintained in the CDNU for conversion of references from True and Magnetic

North. This database is automatically transferred from the MDL cartridge each time the cartridge is inserted if it is

more recent than the existing CDNU database. Once loaded, a magnetic variation database remains in effect until

overwritten by insertion of a new cartridge containing a more recent magnetic variation database.

1. Flight Plan Page — Pressing the FPLN direct access key accesses the Flight Plan page. All information

defining the flight plan is available by scrolling through the Flight Plan Page with the up and down arrow keys.

ORIGINAL

2-202

01-75GAL-1

Two display modes are available: Expanded display shows full display of waypoint attributes; Compact

display shows only horizontal positions.

Load a Flight Plan from the MDL.

a. Press IDX key to access Index Page 1/2.

b. Press down arrow to access Index Page 2/2.

c. Press LS1 to access Start Pages.

d. Scroll up/down to MDL Start Page. Select MDL Start Page with corresponding LS key.

e. Press LS8 to access Flight Plan Select 1/2 Page.

f. Scroll up/down to desired Flight Plan and select with corresponding LS key.

Manual Entry of Waypoints into a Flight Plan.

a. Press FPLN key to access FLIGHT PLAN.

b. Press down arrow to scroll to desired portion of flight plan.

c. If MDL is loaded, insert waypoint by typing fix or NAVAID identifier into scratchpad.

d. If MDL is not loaded or waypoint is not in database, enter coordinates into scratchpad (N1234.5W12345.6).

e. Press LS key to place waypoint into flight plan.

Note

Fix coordinates may be assigned a specific label for display vice the

underlying coordinates and definition. Enter 2-, 3-, 4-, or5-letter label into

the scratchpad preceded by a slash “/” (i.e. /HOME). Press the LS key

adjacent to waypoint coordinates to assign the label.

Deleting Waypoints from the Flight Plan.

a. Press FPLN key to access FLIGHT PLAN.

b. Press down arrow to scroll to desired portion of flight plan.

2-203

ORIGINAL

01-75GAL-1

c. Enter minus symbol (-) into the scratchpad.

d. Press LS key to place waypoint into flight plan.

Note

Current waypoint cannot be deleted. Use DIRect to follow-on waypoint.

Calculate Waypoint Lat/Long from Radial/DME Information.

a. Enter base NAVAID as a waypoint.

b. Enter radial/DME information into scratchpad (e.g. 150/10).

c. Press LS key of NAVAID waypoint.

d. Scratchpad will display calculated coordinates of the radial/DME fix.

e. Verify the accuracy of the calculated position using navigation charts.

f. Enter calculated coordinates into flight plan and label as required.

GPS to INS Crossfill — The CDNU can download up to nine waypoints of a flight plan to the inertial

navigation systems (INS). For crossfill to work correctly, the crewmember must first initialize crossfill

acceptance as follows:

a. Press IDX key to access Index Page 1/2.

b. Press down arrow to access Index Page 2/2.

c. Press LS1 to access Start Pages.

d. Scroll up/down to WPT Start Page. Select WPT Start Page with corresponding LS key.

e. On WPT Start Page, ensure CROSSFILL ENABLE/DISABLE toggle reads ENABLE.

f. Set INS AUTO/MAN/RMT function select switch to RMT.

g. Set INS Display Selector Switch to WPT.

h. Press TK CHG, then INSERT. Verify 00 flashes in From/To display.

i. Verify up to 9 waypoints transferred to INS using WPT selector thumbwheel.

j. Return INS AUTO/MAN/RMT function select switch back to AUTO or MAN.

2.21.4.4.4 Navigation Computations

The function of the area navigation computations is to maintain an estimate of present horizontal position and

velocity. This is done using integrated navigation (INAV) computations that determine the method of computing the

position and velocity depending on the availability of sensor data.

ORIGINAL

2-204

01-75GAL-1

INAV computations are displayed and controlled via the RNAV pages. INAV RNAV pages 1 and 2 display and

control data for integrated navigation. There are two INAV modes available: AUTOmatic and MANual. In MANual,

a colon (:) will appear adjacent to LS2 allowing the operator to toggle between GPS, INS1 or INS2 as the primary

sensor. The default setting is GPS. In AUTOmatic, the primary sensor and navigation mode will be automatically

selected. Lateral scrolling from the INAV RNAV pages will access the GPS RNAV, INS1 RNAV and INS2 RNAV

pages that display specific sensor navigation data; including GPS EHE, FOM and number of satellites, and sensor

deviation from the INAV solution.

2.21.4.4.5 Flight Progress Monitoring

In-flight navigation guidance and tracking information relative to the current waypoint can be obtained from the

PROGress pages. The PROGress pages provide detailed situation awareness displays to indicate the current aircraft

position, TAS, groundspeed, waypoint bearing and distance, waypoint ETE, wind, course deviations, etc. Progress

pages are accessed via the PROG direct access key and vertical scrolling arrow keys. Progress Page 1 provides lateral

guidance information relative to the flight plan, Progress Page 2 provides vertical information relative to VNAV

functions, and Progress Page 3 displays aircraft operating conditions that are independent from the flight plan. Basic

navigational data (bearing, distance and ETE) for flight plan follow-on waypoints may be obtained by accessing the

FPLN page and pressing the LS key next to the corresponding waypoint.

2-205

ORIGINAL

01-75GAL-1

2.21.5 AN/ARC-186(V) VHF AM-FM Radio

The VHF AM-FM communication system consists of a transceiver and a control panel. Manual frequency selection

of 4,080 channels is available in the range of 30.000 MHz to 87.975 MHz in the FM band, and in the range of 108.000

MHz to 151.975 MHz in the AM band. Twenty preset channels are also available, as well as FM and AM emergency

channels. Channel selection is provided from the VHF communication/navigation control panel located on the flight

control pedestal. The No. 1 VHF radio receives 28-Vdc power from the isolated dc bus through the VHF COMM

NO. 1 circuit breaker on the copilot upper circuit breaker panel. The No. 2 VHF radio receives 28-Vdc power from

the essential dc bus through the VHF COMM NO. 2 circuit breaker on the copilot upper circuit breaker panel.

2.21.5.1 VHF AM-FM Radio Tuning and Control

The VHF radios are tuned and controlled via the CDNU Comm page or detailed VHF page. System power is

controlled via the CDNU Power page (a box around the system name indicates the unit is powered). The Comm page

is accessed via the F3 key or via the index page. Tuning is accomplished by entering the appropriate frequency in

the scratchpad and then pressing the line select key next to the corresponding radio. Pressing the line select key with

no frequency in the scratchpad (blank scratchpad) will access the detailed page for the corresponding radio. Quick

tuning of the VHF radios on aircraft without ARC-210 radios (aircraft without AFC-338) can be accomplished by

entering the frequency in the scratchpad and pressing F1 for VHF 1 or F2 for VHF 2. Pressing the F1 or F2 keys with

no frequency in the scratchpad will access the corresponding detailed VHF page (or the detailed V/U page for aircraft

after AFC-338). Returning to the previously selected frequency may be accomplished by tuning 0. For additional

functions and controls of the VHF radios, refer to Figure 2-95.

2.21.5.2 Normal Operation of the VHF AM-FM Radio

Operate the VHF radio as follows:

1. Tune desired frequency in VHF 1 or VHF 2 via the CDNU.

2. To receive, pull the corresponding VHF push-pull mixer switch on the intercommunication control panel

(ICS).

3. Adjust squelch (via CDNU) and volume (via individual mixer switch or master volume knob on ICS panel).

4. To transmit, place the transmission selector on the ICS panel to the VHF 1 or VHF 2 position.

2.21.6 AN/ARC-159(V)1 UHF Command Radio (Aircraft Not Modified by AFC-338)

Two UHF command radio sets, designated UHF No. 1 and UHF No. 2, provide voice transmission and reception

in the frequency range of 225.000 to 399.975 MHz, with 7,000 frequencies in steps of 25 kHz. Receiver and

2-207

ORIGINAL

01-75GAL-1

transmitter tuning is accomplished automatically after a frequency change. In addition, the UHF radio set is capable

of guard frequency reception and transmission and ADF reception. The guard receiver module is self-contained, fix

tuned, set to a guard frequency, and can receive simultaneously with the main receiver. The No. 1 UHF command

radio operates from 28-Vdc power from the isolated dc bus through the UHF NO. 1 circuit breaker on the copilot

upper circuit breaker panel. The No. 2 UHF command radio operates from 28-Vdc power from the essential dc bus

through the UHF NO. 2 circuit breaker on the copilot upper circuit breaker panel.

2.21.6.1 UHF Command Radio Controls

2.21.6.1.1 Radio Controls

The two UHF command radios (see Figure 2-96), located on the flight control pedestal and the copilot side shelf

extension, provide operating controls on the radio. The four-position (OFF, MAIN, BOTH, ADF) function switch

permits selection of the operational mode of the radio. In the MAIN position, the main receiver and transmitter are

operational. In the BOTH position, the functions are operational and the guard receiver is turned on. The ADF

position on the No. 1 UHF radio activates the UHF direction finder.

The three-position (PRESET, MANUAL, GUARD) mode selector switch determines frequency selection and

permits indication of frequency and/or channel selection. The PRESET position permits one of 20 preset channels

to be selected with the preset channel selector knob and displays the channel selected on the readout indicator. The

MANUAL position permits selection of any one of 7,000 frequencies by use of the manual frequency selector

switches. The frequency selected is displayed on the FREQ/(CHAN) readout indicator. The preset channel selector

knob is ineffective when the mode selector switch is in the MANUAL position. The GUARD position shifts the

transceiver to the guard frequency and causes the guard frequency to be displayed on the readout indicator. The preset

CHAN SEL and manual frequency selector switches are ineffective when the mode selector switch is in the GUARD

position.

Note

D The GUARD position of the mode selector switch should not be used

except in actual emergencies.

D When utilizing the radio mode selector (GUARD/MANUAL/PRESET)

switch, ensure that the switch is cleanly placed into one of the three detent

positions. If the switch is placed between two of the detent positions, the

radio FREQUENCY DISPLAY may be either blank or will not display the

correct preset channel/frequency. Cycling power to the radio will correct

the situation.

The PRESET CHAN SEL knob is used to select any one of 20 preset channels when the mode selector switch is in

the PRESET position.

The BRT/TEST knob is used to adjust light intensity of the readout lamps and to test the readout lamps when the

switch is positioned to TEST.

The four spring-loaded toggle switches below the readout indicator are used to select the operating frequency when

the mode selector switch is in MANUAL.

The VOL knob is used to adjust the level of the audio signal.

The TONE pushbutton, when depressed, causes the transmitter to transmit a 1020-Hz tone signal.

The SQL switch enables or disables the main receiver squelch.

ORIGINAL

2-208

C-130T. FLIGHT MANUAL (2006) - page 4