F16C/D. FLIGHT MANUAL (2002) - page 8

T.O. GR1F16CJ1

198

HYDRAULIC SYSTEM

Refer to figure 133. Hydraulic pressure is supplied

by 3000 psi hydraulic systems designated as systems

A and B. The systems are powered by two

independent enginedriven pumps located on the

ADG. Each system has a reservoir to store hydraulic

fluid. The reservoirs are pressurized by their

respective hydraulic system to insure positive

pressure at the pump. For hydraulic system cooling,

refer to ENGINE FUEL SUPPLY SYSTEM, this

section.

Both systems operate simultaneously to supply

hydraulic power for the primary flight controls and

LEF's. If one of the systems should fail, the

remaining system provides sufficient hydraulic

pressure; however, the maximum actuation rate of

the FLCS is reduced. System A also supplies power

to the FFP and the speedbrakes. All remaining

utility functions, consisting of the gun and gun purge

door, AR system, LG, brakes, and NWS, are supplied

by system B. System B also charges the brake/JFS

accumulators (which provide start power for the JFS

and backup pressure for the brakes), provided the

engine is rotating at a minimum of 12 percent rpm.

System B takes between 40 seconds (hot ambient

conditions) and 60 seconds (cold ambient conditions)

to recharge the brake/JFS accumulators.

The LG can be extended pneumatically in the event

of hydraulic system B failure. Should both hydraulic

systems fail, a third hydraulic pump located on the

EPU automatically provides hydraulic pressure to

system A. Refer to EMERGENCY POWER UNIT

(EPU), this section, for a further discussion of the

EPU.

Each hydraulic system has an FLCS accumulator

which is isolated from the main system by check

valves. These FLCS accumulators serve a dual

function. If demand exceeds the pump maximum

flow rate during rapid control surface movement, the

FLCS accumulators provide additional hydraulic

pressure. Also, if both hydraulic systems fail, the

FLCS accumulators provide adequate hydraulic

pressure to the flight controls while the EPU comes

up to speed. Refer to SERVICING DIAGRAM, this

section, for servicing/specifications information.

HYD PRESS INDICATORS AND WARNING LIGHT

Refer to figure 134.

HYD PRESS Indicators

The HYD PRESS indicators, one for system A and

one for system B, are located on the right auxiliary

console. The indicators are powered by emergency ac

bus No. 2.

HYD/OIL PRESS Warning Light

A HYD/OIL PRESS warning light, located on the

right glareshield, comes on when hydraulic system

A or B pressure drops below 1000 psi or when engine

oil pressure drops below 10 (

"

2) psi. For the oil

pressure function only, there is a 30second time

delay in the light circuit to minimize transient lights

during negative g maneuvers. The light is powered

by battery bus No. 1.

EMERGENCY POWER UNIT (EPU)

Refer to figure 135. The EPU is a selfcontained

system which simultaneously provides emergency

hydraulic pressure to system A and emergency

electrical power. The EPU automatically activates

when both main and standby generators fail or when

both hydraulic system pressures fall below 1000 psi.

The EPU may be operated manually regardless of

failure conditions.

The EPU requires dc power from either battery bus

No. 1 or No. 2 for automatic or manual activation.

When the EPU is operating, the emergency ac and dc

buses are powered by the EPU generator. To reduce

electrical loads, the nonessential and essential dc

buses are unpowered whenever the EPU is operating

(except when activated for ground test using the

EPU/GEN test switch).

When operating, the EPU augments hydraulic

system A as required. If the normal system A

hydraulic pump fails, the EPU is the only source of

system A pressure.

The EPU uses engine bleed air and/or hydrazine to

operate. Normally, engine bleed air is used to

maintain operating speed. When bleed air is

insufficient, hydrazine augmentation automatically

occurs. Hydrazine is always used when the EPU is

commanded to start except when activated during

ground test using the EPU/GEN test switch.

T.O. GR1F16CJ1

199

On system command, hydrazine is forced by nitrogen

pressure into a decomposition chamber. The gaseous

products of the reaction spin the turbine/gearbox

which then powers the EPU generator and hydraulic

pump. Hydrazine exhaust is vented overboard on the

lower inboard side of the right strake and consists

primarily of nitrogen, hydrogen, ammonia, and

water. The temperature of exhaust gases can reach

1600

_

F and will ignite in the presence of a flame. The

exhaust gases have an ammonia odor, are irritating

to the nose and eyes, and should be avoided to the

maximum extent possible.

EPU CONTROLS AND INDICATORS

Refer to figure 136.

EPU Ground Safety Switch

The ground safety switch, located on the right side of

the engine inlet, is used to disable the EPU on the

ground. With the EPU safety pin installed, the EPU

does not operate.

EPU Switch

The EPU switch, located on the EPU control panel, is

a threeposition toggle switch.

Functions are:

D

OFF

S

Prevents or terminates EPU operation on the

ground (WOW).

S

Does not prevent or terminate EPU operation in

flight for main and standby generator failures if

switch was cycled or placed to NORM at anytime

since takeoff (since WOW).

S

Prevents EPU operation in flight if switch has

remained in the OFF position since takeoff (since

WOW).

S

Terminates EPU operation in flight except during

main and standby generator failures.

D

NORM - The system is armed for automatic

operation except during engine shutdown on the

ground. With WOW and throttle in OFF, the EPU

does not activate when the main and standby

generators drop off line.

D

ON - Commands EPU to run regardless of failure

conditions. Operation will cease when switch is

positioned to OFF except for main and standby

generator failures in flight.

The switch has a split guard; the top half can be raised

to move the switch to ON, and the bottom half can be

raised to move the switch to OFF. When both sections

of the guard are down, the switch is retained in the

NORM position.

EPU Run Light

The EPU run light, located on the EPU control panel,

illuminates when the EPU turbine speed is within the

proper range and the EPUdriven hydraulic pump

discharge pressure is above 2000 psi.

HYDRAZN Light

The HYDRAZN light, located on the EPU control

panel, illuminates when the EPU is commanding

hydrazine for operation (whether hydrazine is

available or not) or if a primary speed control failure

has occurred.

AIR Light

The AIR light, located on the EPU control panel,

illuminates whenever the EPU has been commanded

to run with the EPU safety pin removed. It remains

on even when the EPU is augmented by hydrazine.

EPU/GEN Test Switch

The EPU/GEN test switch, located on the TEST

switch panel, has positions of OFF and EPU/GEN.

The switch is springloaded to the OFF position. It

provides a means to test the EPU generator and EPU

PMG output to FLCS on the ground without using

hydrazine.

EPU FUEL Quantity Indicator 

C

 

DF

Refer to figure 13. The EPU FUEL quantity

indicator, located on the right auxiliary console, is

graduated 0100 and indicates the percent of

hydrazine remaining. The indicator is powered by

battery bus No. 2.

Hydrazine Leak Detector

The hydrazine leak detector is a silicone base,

mustard yellow disc visible through access door 3208.

The viewing area is black on one half to provide

contrast with the mustard yellow disc. The mustard

yellow turns purple/black in the presence of

hydrazine and/or its vapors, indicating a leak in the

EPU and/or fuel tank system.

T.O. GR1F16CJ1

1100

GR1F-16CJ-1-0037-1X37

Hydraulic Power Supply

(Typical)

FILTER

ENGINE

DRIVEN

HYDRAULIC

PUMP

EPU

HYDRAULIC

PUMP

FILTER

FLCS

ACCUMULATOR

THERMAL

BYPASS

FUEL/OIL

HEAT EX-

BRAKE/JFS

ACCUMULATORS

HYD PRESS

INDICATOR

WARNING LIGHT

LEF'S

RUDDER

FLAPERONS

SPEEDBRAKES

FFP

LG SYSTEM

NWS

HYDRAULIC

RESERVOIR

GUN SYSTEM

AR SYSTEM

BRAKE SYSTEM

JFS SYSTEM

RESERVOIR

PRESSURIZATION

ACCUMULATOR

RESERVOIR

PRESSURIZATION

ACCUMULATOR

DUMP AND

RELIEF VALVE

DUMP

AND

RELIEF

MANIFOLD

HORIZONTAL

TAILS

CHANGER

B

P

SYSTEM A

S

T

PRESS

HYD/OIL

DRAG CHUTE

SYSTEM

Figure 133.(Sheet 1)

T.O. GR1F16CJ1

1101

GR1F-16CJ-1-0037-2X37

FLCS

ACCUMULATOR

FILTER

ENGINE

DRIVEN

HYDRAULIC

PUMP

FILTER

LG DOORS

UPLOCK

ACTUATED

FILTER

WARNING LIGHT

HYD PRESS

INDICATOR

HYDRAULIC

RESERVOIR

DUMP AND

RELIEF VALVE

B

P

SYSTEM B

S

T

PRESS

HYD/OIL

DRAG CHUTE

ACCUMULATOR

S

B

P

T

LEGEND:

ISOLATION VALVE

BLEED VALVE

FILL CONNECTOR

QUICK DISCONNECT

CHECK VALVE

PRESSURE SWITCH

PRESSURE TRANSMITTER

BYPASS

ELECTRICAL

PRESSURE

RETURN

SUPPLY

Figure 133.(Sheet 2)

T.O. GR1F16CJ1

1102

HYD/OIL PRESS Warning Light (Red)

System A HYD PRESS Indicator

System B HYD PRESS Indicator

HYD PRESS Indicators and Warning Light

(Typical)

GR1F16CJ10036X37

2

3

1.

2.

3.

2

3

1

1

C DF

DR

Figure 134.

EPU Fired Indicator

The EPU fired indicator is located next to the EPU

ground safety switch on the right side of the engine

inlet. Normally, the indicator displays a gray and

black disc. If the EPU has been activated, the

indicator displays six equally spaced black and white

triangles.

EPU OPERATION

The EPU is designed to operate automatically for

main and standby generator failure, dual hydraulic

system failure, PTO shaft or ADG failure, and engine

flameout or if the engine is shut down in flight. The

EPU can also be activated manually. After receiving

any start command, the EPU requires approximately

2 seconds to come up to speed.

EPU startup may not be audible. Once operating,

however, the EPU may be heard but does not sound

the same as during the EPU ground check. A lack of

sound during EPU startup does not indicate lack of

EPU operation which must be confirmed by

monitoring the EPU run light. EPU rpm is controlled

by three speed controls. The primary and secondary

speed controls are based on EPU rpm. The tertiary

speed control is based on EPU PMG frequency.

When the EPU is operating, engine thrust settings

should be maintained to prevent using hydrazine.

This normally requires a minimum of 

PW 229

 7580,

129

GE

 8290 percent rpm depending on pressure

altitude.

If the engine fails, hydrazine alone is used to power

the EPU. With hydrazine only, operating time of the

system is approximately 10 minutes under normal

load requirements. Increased flight control move

ment reduces this operating time. When the EPU is

the sole source of hydraulic power, EPU loss results

in loss of aircraft control.

T.O. GR1F16CJ1

1103

GR1F-16CJ-1-0038A37

OPEN IF EPU

SAFETY PIN

INSTALLED

LEGEND:

BLEED AIR
HYDRAZINE FUEL
HYDRAULIC FLUID SUPPLY

EPU START UP AND CONTROL POWER

EPU TEST RUN COMMAND

CLOSED ON

START, MAIN

GEN ON LINE

AUTO ARM/

DISABLE

OPEN WITH

WOW &

THROTTLE

BELOW IDLE

RUN LIGHT OFF

FOR OVER OR

UNDERSPEED

CONDITION

EPU/GEN TEST

SWITCH

EPU COMMAND INDICATION

HIGH PRESSURE

BLEED AIR

BLEED AIR

VALVE

RUN

COMMAND

(AUGMENT)

TEST RUN

COMMAND

(BLEED AIR

ONLY)

OVERSPEED SHUTOFF COMMAND

(TERTIARY CONTROL)

TO EMERGENCY

AC BUSES

TO CONVERTER/

REGULATORS

CLOSED FOR

PRESSURE > 2000 PSI

TO HYD

SYS A

EPU RUN LIGHT

CLOSED IF

MAIN GEN

OFF LINE

CLOSED IF

STANDBY GEN

OFF LINE

SPEED

MONITOR

HYDRAULIC

PUMP

CONTROL VALVES

5 KVA

GENERATOR

AC POWER

GENERATOR

CONTROL UNIT

HYDRAZINE FUEL

HYD SYS A

CLOSED FOR

PRESSURE < 1000 PSI

28 VDC PWR

MAIN

GENERATOR

STANDBY

GENERATOR

AUGMENT

MODE

BLEED AIR

MODE ONLY

Shown in augment mode with main

Emergency Power Unit Schematic (Typical)

EPU GROUND

SAFETY SWITCH

SOLENOID

ELECTRICAL

MECHANICAL

FROM HYD SYS A RSVR

EPU

EPU

CONTROLLER

VALVE

ASSY

NITROGEN

EPU FUEL

QUANTITY

PRESSURE

INDICATOR

GASEOUS NITROGEN

FILL

CONNECTOR
QUICK

DISCONNECT

HYDRAULIC PRESSURE

HYD SYS B

EPU PMG FAIL INDICATION FROM CONVERTER/REGULATORS

EPU GENERATOR FAIL INDICATION

STANDBY GENERATOR

FAIL INDICATION

MAIN GENERATOR

FAIL INDICATION

ELEC

SYS

P

M

G

NOTE:

and standby generators failed.

PX III

PX II

7 KVA

Figure 135.

T.O. GR1F16CJ1

1104

GR1F-16CJ-1-0039X37

1. HYDRAZN Light (Amber)

2. AIR Light (Amber)

3. EPU Run Light (Green)

4. EPU Switch

EPU Control Panel

(Typical)

C DF

4

3

2

1

Figure 136.

LANDING GEAR (LG) SYSTEM

The LG system is normally operated by hydraulic

system B. The NLG is extended and retracted by

hydraulic pressure. The MLG's are retracted

hydraulically but are extended by freefall assisted by

airloads. All the LG doors are hydraulically activated

with electrical sequencing during retraction and

mechanical sequencing during extension. If hydrau

lic system B fails, the LG may be extended

pneumatically.

MAIN LANDING GEAR (MLG)

The two MLG's are independent of each other and

retract forward with a mechanical wheel twist into two

separate wheel wells. Each MLG wheel is equipped

with three fusible (thermal pressure relief) plugs.

NOSE LANDING GEAR (NLG)

The NLG retracts aft with a 90degree mechanical

wheel twist into the wheel well. A torque arm

quickdisconnect is provided so that the nosewheel

can be turned beyond the steerable range for towing.

LANDING GEAR CONTROLS AND INDICATORS

Refer to figure 137. The LG control panel is located

on the left auxiliary console.

Landing Gear Handle

The LG handle, located on the LG control panel has

a wheelshaped grip. Movement of the handle

operates electrical switches (powered by emergency

dc bus No. 2) to command LG retraction or extension.

A warning light in the LG handle, powered by battery

bus No. 2 illuminates when the LG and doors are in

transit or have failed to lock in the commanded

position. The warning light also illuminates when all

LG's are not down and locked, airspeed is less than

190 knots, altitude is less than 10,000 feet, and rate

of descent is greater than 250 feet per minute. The

handle is locked in the DN position when the aircraft

is on the ground (weight on wheels). In flight, a signal

from the left MLG WOW switch automatically

activates a solenoid which unlocks the handle,

allowing movement to the UP position. The handle is

locked in the UP position to prevent LG extension

during high g maneuvers.

Landing Gear Handle Down Permission Button

The LG handle down permission button, located on the

LG handle, unlocks the handle electrically to permit

movement to the DN position. The button energizes an

electrical solenoid which releases the springactuated

handle lock. The button must be depressed before

downward force is applied to the LG handle. The

electrical solenoid may not unlock the handle while

any appreciable downward force is applied.

DN LOCK REL Button

C

 

DF

 The DN LOCK REL button, located on the LG

control panel, when depressed, mechanically unlocks

the springactuated handle lock if the electrical

solenoid should fail or not be powered. It overrides all

electrical LG control signals. Depressing this button

and raising the LG handle on the ground retracts the

LG. The downlock release button may not unlock the

LG handle while any appreciable downward force is

applied. 

DR

 For DN LOCK REL button differences,

refer to F16D AIRCRAFT, this section.

T.O. GR1F16CJ1

1105

GR1F-16CJ-1-0040A37

2

3

HORN SILENCER Button

ALT GEAR Handle

SPEED BRAKE Position Indicator

STORES CONFIG Switch

GND JETT ENABLE Switch (Lever Lock)

    ALT FLAPS Switch

WHEELS Down Lights (Green)

HOOK Switch (Lever Lock)

DN LOCK REL Button

LG Handle Down Permission Button

LG Handle

LG Handle Warning Light (Red)
LANDING TAXI LIGHTS Switch

Landing Gear Control Panel (Typical)

C DF

DR

EMER STORES JETTISON Button

(Covered)

ANTI-SKID Switch

ALT GEAR Reset Button

BRAKES Channel Switch

1

16

15

14

13

12

8

7

6

5

4

11

10

9

1

16

8

7

6

5

17

10

13

12

11

3

2

1.

2.

3.

4.

5.

6.

7.

8.
9.

10.

11.

12.

13.

14.

15.

16.

17.

Figure 137.

T.O. GR1F16CJ1

1106

ALT GEAR Handle

The ALT GEAR handle, located just outboard of and

below the LG control panel, is used to extend the LG

if normal extension is not possible. Pulling the ALT

GEAR handle supplies pneumatic pressure to open all

LG doors, extend the NLG, and shut off the LG selector

hydraulic valve. The LG/hook emergency pneumatic

bottle is also used to lower the hook and contains

sufficient pneumatic pressure for one LG extension

and to hold the hook down. The bottle cannot be

recharged in flight. Since pneumatic pressure is

reduced by expansion as the actuators extend, less

than the normal extending force is available.

An LG reset button, located on the ALT GEAR handle,

provides a means of retracting the LG after an alternate

extension if system B hydraulic pressure is available.

LG Warning Horn

The LG warning horn is an intermittent fixed volume

signal which sounds in the headset when the NLG or

MLG is not down and locked and all the following

conditions exist:

D

Airspeed is below 190 knots.

D

Pressure altitude is less than 10,000 feet.

D

Rate of descent is greater than 250 fpm.

HORN SILENCER Button

The HORN SILENCER button is located on the LG

control panel. Depressing the button silences the LG

warning horn. If the warning condition is eliminated,

the horn resets. If it is not eliminated, subsequent LG

audio warnings do not occur.

TO/LDG CONFIG Warning Light

The TO/LDG CONFIG warning light, located on the

right glareshield, illuminates in flight whenever

pressure altitude is less than 10,000 feet, airspeed is

less than 190 knots, rate of descent is greater than

250 fpm, and either of the following conditions exists:

D

TEF's not full down.

D

NLG or either MLG not down and locked

(accompanied by LG warning horn).

The TO/LDG CONFIG warning light illuminates on

the ground if TEF's are not full down.

With TEF's full down, rapid reversals of roll

command inputs may cause the TO/LDG CONFIG

warning light to momentarily illuminate if the

altitude, airspeed, and rate of descent conditions

outlined above are met or WOW.

WHEELS Down Lights

The three green WHEELS down lights, located on

the LG control panel, are arranged on the silhouette

of the aircraft. When any LG is down, its respective

light is on. A safe up and locked LG condition is

indicated when all three of the lights and the LG

handle warning light are off. The lights are powered

by battery bus No. 1 (to energize downlock relays)

and emergency dc bus No. 1 (to illuminate lights).

Landing Gear WeightonWheels (WOW)

Switches

The LG WOW switches, located on both MLG's and on

the NLG, operate as a function of LG strut extension

to allow or terminate various system functions.

Refer to figure 138 for a list of systems affected by the

WOW switches and symptoms of WOW switch failure.

LANDING GEAR OPERATION

Movement of the LG handle to the UP position causes

the following events:

D

LG handle warning light illuminates.

D

LG unlocks and retracts.

D

Three WHEELS down lights go off.

D

MLG wheel spin is stopped.

D

LG doors close and lock.

D

LG handle warning light goes off.

D

Hydraulic pressure removed from LG.

D

FLCS switches to cruise gains.

D

TEF's retract to streamlined position.

D

Electrical power is removed from brake channel 1.

Movement of the LG handle to the DN position causes

the following events:

D

LG handle warning light illuminates.

D

LG doors and LG unlock, extend, and lock into place.

D

Three WHEELS down lights illuminate.

D

LG handle warning light goes off.

D

TEF's extend.

D

FLCS switches to takeoff and landing gains.

D

PW 229

 LG DN nozzle scheduling is activated.

D

Speedbrakes close to 43 degrees if not overridden.

D

Electrical power is supplied to brake channel 1.

T.O. GR1F16CJ1

1107

LG WOW Switch

RIGHT MLG  SYSTEMS

Aircraft Battery

Air Data Probe

Altimeter (ELECT)

AOA Probes

Brakes/Antiskid

ECS

Engine Controls

EPU

FCR

FLCC

LG Warning

Pitot Probe

Probe Heat Monitor

SMS

VMS

C

Fails to Ground Position in Flight

Fails to InFlight Position on Ground

FCR does not transmit

FCR transmits

Stores cannot be emergency jettisoned with LG down unless

GND JETT ENABLE switch is in ENABLE

Stores can be emergency jettisoned with GND JETT ENABLE switch

in OFF

 VMS is inoperative

C

 VMS is operative unless INHIBIT is selected

C

Brakes can be applied before touchdown if toe brakes are

depressed

With simultaneous failure of left and right MLG WOW switches

and ANTISKID switch in ANTISKID, toe brakes are inoperative

when groundspeed is less than 20 knots

ANTISKID switch holds in PARKING BRAKE with throttle in OFF to

IDLE range

With simultaneous failure of left and right MLG WOW switches,

ANTISKID switch must be held in PARKING BRAKE to operate

parking brake

With simultaneous failure of left and right MLG WOW switches,

ACFT BATT FAIL light indicates aircraft battery failure (voltage 20V

or less) or battery charger failure

ACFT BATT FAIL light indicates aircraft battery failure only

EPU is commanded on during engine shutdown; operation cannot

be terminated with the EPU switch

LG and low speed warning tones are inoperative

C

Probe heat monitor is inoperative unless TEST or PROBE HEAT is

selected

Probe heat monitor is operative

All probe heaters except total temperature are on

FLCS BIT cannot be initiated

Figure 138.(Sheet 1)

T.O. GR1F16CJ1

1108

LG WOW Switch

LEFT MLG  SYSTEMS

Aircraft Battery
AOA Probe (right)
Brakes/Antiskid
Chaff/Flare Dispenser
EPU
FLCC

Ground Test Panel (fuel pump lights)
JFS Ground Cutout
LG Handle
LG Warning
Total Temperature Probe
VMS

D

Fails to Ground Position in Flight

Fails to InFlight Position on Ground

Chaff/flare dispenser is inoperative

Chaff/flare dispenser is operative

AOA probe heater (right) is on

JFS shuts down automatically during engine start

JFS does not shut down automatically during engine start

LG UP position cannot be selected unless DN LOCK REL button is

depressed

LG UP position can be selected without DN LOCK REL button

depressed

TO/LDG CONFIG warning light is on with TEF's not down

TO/LDG CONFIG warning light is off with TEF's up

Total temperature probe heater is inoperative

Total temperature probe heater is on

VMS is inoperative

D

VMS is operative unless INHIBIT is selected

D

Brakes can be applied before touchdown if toe brakes are

depressed

With simultaneous failure of right and left MLG WOW switches

and ANTISKID switch in ANTISKID, toe brakes are inoperative

when groundspeed is less than 20 knots

ANTISKID switch holds in PARKING BRAKE with throttle in OFF to

IDLE range

With simultaneous failure of right and left MLG WOW switches,

ANTISKID switch must be held in PARKING BRAKE to operate

parking brake

Fuel pump lights on external ground test panel are inoperative

With simultaneous failure of right and left MLG WOW switches,

ACFT BATT FAIL light indicates aircraft battery failure (voltage 20V

or less) or battery charger failure

ACFT BATT FAIL light indicates aircraft battery failure only

LG and low speed warning tones are inoperative

D

EPU is commanded on during engine shutdown; operation cannot

be terminated with the EPU switch

FLCS BIT cannot be initiated

Figure 138.(Sheet 2)

T.O. GR1F16CJ1

1109

LG WOW Switch

NLG  SYSTEMS

Air Data Probe

AOA Probe (Left)

AR

FLCP

FLCS Power

NWS

Pitot Probe

Speedbrakes

C

C

Fails to Ground Position in Flight

Fails to InFlight Position on Ground

Air data, pitot, and left AOA probe heaters are on

AOA indicator displays zero degrees

A/R DISC button is inoperative

C

A/R DISC button is operative

C

FLCS fails BIT

NWS can be engaged and follows rudder inputs with NLG down

NWS is inoperative

Speedbrakes are not limited to 43 degrees with right MLG down

and locked

Speedbrakes do not remain open more than 43 degrees

ACFT BATT TO FLCS light indicates aircraft battery is supplying

power to one or more FLCS branches

ACFT BATT TO FLCS light indicates aircraft battery is supplying

power to one or more FLCS branches (bus voltage 25 vdc or less)

FLCS PMG light indicates FLCS PMG power is not available at one

or more FLCS branches

FLCS PMG light indicates the FLCS PMG is not supplying power to

any FLCS branches

Figure 138.(Sheet 3)

T.O. GR1F16CJ1

1110Change 1

NOSEWHEEL STEERING (NWS) SYSTEM

The NWS is electrically controlled using dc bus No. 1

power and is hydraulically operated using system B

pressure. Steering signals are provided through the

rudder pedals. Should NWS be engaged with the

rudder pedals displaced, the nosewheel drives to the

rudder pedal commanded position. NWS is limited to

32 degrees in each direction; however, turn radius can

be reduced by using inside brake. NWS is

automatically disengaged when the NLG strut is

extended. NWS is not available following an

alternate LG extension and may not be available

anytime the nosewheel WHEELS down light is not

illuminated.

NWS CONTROLS AND INDICATORS

Refer to figure 13.

NWS A/R DISC MSL STEP Button

The NWS A/R DISC MSL STEP button, located on the

outboard side of the stick, is used to engage or

disengage NWS when the aircraft is on the ground.

Once depressed, NWS is engaged and the button may

be released. If the button is held depressed,

continuous NWS is provided.

NWS Light

The NWS light, the center element of the AR/NWS

status indicator located on the top of the glareshield,

illuminates green when NWS is engaged. NWS does

not operate even though the NWS light is illuminated

when the NWS FAIL caution light is on or when

system B hydraulic pressure is unavailable. On the

ground, NWS continues to operate with the AIR

REFUEL switch in OPEN even though the NWS light

is off.

NWS FAIL Caution Light

The NWS FAIL caution light, located on the caution

light panel, illuminates when a failure in the NWS

system has caused electrical power to be switched off.

NOSEWHEEL STEERING (NWS) SYSTEM  

D

Either cockpit can control the NWS. Control is

accomplished by means of an NWS control button/in

dicator located in both cockpits just aft of the stick.

Depressing the button/indicator transfers control of

the NWS; the indicator illuminates green in the

cockpit which has control. Control then remains in

that cockpit even if the engine is shut down and/or

electrical power is removed. NWS can only be

engaged and operated from the cockpit which has

control. When NWS is selected, the NWS light

illuminates green in both cockpits. The aft stick

paddle switch allows immediate override of the

forward cockpit if the STICK CONTROL switch on

the TEST switch panel is in AFT; the NWS control

button/indicator in the aft cockpit and OVRD light

illuminates. The front cockpit paddle switch cannot

override the aft cockpit regardless of the position of

the STICK CONTROL switch. With the AIR

REFUEL switch in OPEN, NWS can be engaged or

disengaged from either cockpit without using the

paddle switch regardless of which cockpit has control.

WHEEL BRAKE SYSTEM

Each MLG wheel is equipped with a hydraulically

powered multiple disc brake. The brakes are

electrically controlled by conventional toe brake

pedals. The amount of braking gradually increases as

pedal pressure is applied. A parking brake is also

provided. An antiskid system protects against blown

tires and is only available when using toe brakes.

D

 Brakes may be applied singly or simultaneously

from the forward or rear cockpits. The brake signals

from both cockpits are additive so that the total signal

to the brakes is the sum of the pedal forces from both

cockpits.

Brake hydraulic power is supplied by system B. If

system B fails or the engine is operating at less than

12 percent rpm, the toe brakes and parking brake are

available until the brake/JFS accumulators deplete.

Continuous use of the toe brakes, even with the

parking brake set, depletes accumulator fluid and

causes loss of all braking capability after approxi

mately 75 seconds (brake/JFS accumulators initially

fully charged). When holding the aircraft stationary,

use of the parking brake is preferred since brake/JFS

accumulator fluid is not depleted.

TOE BRAKE SYSTEM

Refer to figures 139 and 140. The toe brakes use

electrical power from the FLCC and CHAN 1 and

CHAN 2 dc power sources. The brake pedals require

FLCC power to operate. The pedal signals are

supplied to the 

b2t

 brake control/antiskid assembly

LESS

 

b2t

 brake control box which, in turn, uses both

CHAN 1 and CHAN 2 dc power sources to operate

valves for controlling hydraulic pressure to the

brakes. CHAN 1 and CHAN 2 are powered by battery

buses No. 1 and No. 2, respectively. 

PX III

 In addition,

there is an alternate power source for CHAN 2 on

emergency dc bus No. 2.

T.O. GR1F16CJ1

1111

1F-16X-1-0026X

BRAKE
CHAN 1

BRAKE
CHAN 2

C

A

D

B

L

R

FLCC
BRANCHES

TOE BRAKES

Toe Brake System

Figure 139.

The electrical power sources are grouped to provide

two redundant channels. Channel 1 uses FLCC

branches A and C and CHAN 1 dc power. Channel 2

uses FLCC branches B and D and CHAN 2 dc power.

If one FLCC branch fails, one toe brake in either

CHAN 1 or CHAN 2 is inoperative.

An inoperable FLCC branch may illuminate the

FLCS FAULT caution light and generate a BRK PWR

DEGR PFL. FLCS PWR lights on the TEST switch

panel should be used to determine the proper

BRAKES channel switch position.

After engine shutdown (main and standby generators

and FLCS PMG not operating), the brakes remain

powered as long as the MAIN PWR switch is not

moved out of MAIN PWR. If the MAIN PWR switch

is moved to BATT, the FLCS relays open and the

FLCC is no longer powered by the aircraft battery.

Therefore, the toe brakes are inoperative.

Regardless of which channel is selected, hydraulic

pressure to three of the six pistons in each brake is

controlled by electrical power from one dc power

source and pressure to the other three pistons of each

brake is controlled by electrical power from another

dc power source. A loss of one dc power source when

CHAN 1 is selected results in degraded brake

operation (only onehalf of the pistons are powered

and significantly more brake pedal force than normal

is required to stop). Due to redundancy features,

selecting CHAN 2 may restore full braking. If all dc

power sources fail or if all FLCC branches are off, the

toe brakes are totally inoperative.

Channels 1 and 2 use separate redundant circuit

elements for controlling the brakes and operate the

same except that when CHAN 1 is selected, both dc

power sources are switched off when the LG handle

is up. With CHAN 1 selected, the brakes only operate

with the LG handle down; with CHAN 2 selected, the

brakes are operable with the LG handle either up or

down. If the LG handle is stuck in the UP position,

CHAN 2 must be selected to achieve braking.

SPIN DOWN BRAKING SYSTEM

The spin down braking system provides hydraulic

brake pressure to stop MLG wheel spin during LG

retraction. The hydraulic pressure is relieved when

the LG is up and locked.

BRAKES CHANNEL SWITCH 

C

 

DF

The BRAKES channel switch, located on the LG

control panel, has positions of CHAN 1 and CHAN 2

and allows wheel brake system switching. CHAN 1 is

the normal position.

PARKING BRAKE 

C

 

DF

The parking brake is activated by the ANTISKID

switch located on the LG control panel, and supplies

full, unmetered pressure to three of the six pistons in

each brake. The parking brake holds the aircraft

stationary without the use of toe brakes. It can also be

used for emergency braking if the toe brakes are

inoperative. The parking brake is powered by battery

bus No. 2 and system B hydraulics or one brake/JFS

accumulator (the brake/JFS accumulator which is

not used for START 1).

T.O. GR1F16CJ1

1112

GR1F-16CJ-1-1042-1X37

WHEEL

SPEED

SENSOR

PREBRAKE

RESTRICTOR

VALVE

LG UP

PRESSURE

SHUTTLE

VALVE

PARK

VALVE

BRAKE CONTROL/

ANTI-SKID ASSY

TOE

BRAKES

FLCS

INVERTERS

BRAKE

CHAN 2

BRAKE

CHAN 1

CHANNEL SELECTOR

CHANNEL 1

CHANNEL 2

ANTISKID

CAUTION

LIGHT

RELAY

28 VDC

BATTERY

BUS

NO. 2

26 VAC 800 H

4 INDEPENDENT EXCITATION POWER

SOURCES FROM FLCS INVERTERS

z

GROUND

AIR

>1 INCH ABOVE

NEAR IDLE

THROTTLE

POSITION

SWITCH

MLG WOW

L

R

B

D

A

C

ANTI

SKID

CHANNEL 1

OR

CHANNEL 2

OUTPUT

28 VDC

BATTERY

BUS

NO. 1

Wheel Brake Schematic (Typical)

IDLE

Figure 140.(Sheet 1)

T.O. GR1F16CJ1

1113

GR1F-16CJ-1-1042-2X37

HYD SYS B PRESSURE

HYD

RETURN

HAND

PUMP

TO JFS

SHUTOFF VALVE

RIGHT

METERING

VALVE

LEFT

METERING

VALVE

SHUTOFF VALVE

SUPPLY HYDRAULIC CIRCUITS

WHEEL

SPEED

SENSOR

RIGHT

BRAKE

SHUTTLE

VALVE

LEFT

BRAKE

SHUTTLE

VALVE

HYD POWER

SUPPLY

HYD RETURN

BRAKE HYD

CIRCUIT

PARKING BRAKE

CIRCUIT

LEGEND:

ELECTRICAL

MECHANICAL

CHECK VALVE

ACCUMULATOR

ACCUMULATOR

Figure 140.(Sheet 2)