F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 41

T.O. GR1F16CJ1

343

Pulling the CANOPY JETTISON

Thandle other than straight out may

cause the handle to jam.

3.

MANUAL CANOPY CONTROL handcrank -

Push in and rotate ccw.

Use of the CANOPY JETTISON T

handle or MANUAL CANOPY CON

TROL handcrank may result in seri

ous injury. To minimize chances of

injury, immediately release the handle

when the canopy starts to separate.

Ejection Seat Failure

If the ejection seat fails to function after the ejection

handle is pulled and the canopy has separated from

the aircraft, there are no provisions designed into

the escape system for manual bailout.

DITCHING

Ditch the aircraft only as a last resort. All attempts

to eject should be accomplished prior to ditching.

ELECTRICAL SYSTEM FAILURES

Electrical system failures are indicated by illumina

tion of the ELEC SYS caution light and one or more

ELEC control panel lights (in any combination). After

accomplishing the appropriate emergency proce

dures, refer to EMERGENCY POWER DISTRIBU

TION, this section, to determine inoperative

equipment for any remaining ELEC control panel

lights.

FLCS PMG Failure

If all four branches of the FLCS PMG fail in flight,

the FLCS PMG light illuminates. The converter/reg

ulator automatically selects the power source with

the highest voltage from the available alternate

sources. Other FLCS power sources are the main

generator, the standby generator, the EPU generator,

the EPU PMG, and the aircraft battery.

If FLCS PMG light illuminates:

1.

Land as soon as practical.

Single Generator Failures (in Flight)

A single generator failure is indicated by illumina

tion of either the MAIN GEN or STBY GEN light.

A mechanical failure which affects the standby

generator may also affect the FLCS PMG causing

illumination of both the STBY GEN and FLCS

PMG lights. Actions required in this circumstance

are the same as those for illumination of the MAIN

GEN or STBY GEN light; thus, this failure is also

categorized as a single generator failure.

Illumination of the MAIN GEN light indicates that

one or both nonessential ac buses are not being

powered by the main generator. The light may

illuminate if the main generator fails, if a main

power contactor trips off one or both nonessential

ac buses, or if a shorting failure of an overcurrent

sensing contactor (OCSC) or other wiring/equipment

occurs. Refer to PARTIAL ELECTRICAL POWER

LOSS, this section, for discussion of OCSC failures. In

all cases, the standby generator should automatically

come on line to power the essential and emergency

buses which are not being powered by the main

generator. The nonessential dc bus is not powered.

The main generator may be reset by depressing the

ELEC CAUTION RESET button or cycling the MAIN

PWR switch; however, moving the switch out of

MAIN PWR removes standby generator power and

causes the EPU to activate. A reset attempt should

not be made if the MAIN GEN light was preceded by

a 23 second loss of power to the HUD, MFD's, and

other cockpit equipment. Refer to EMERGENCY

POWER DISTRIBUTION, this section, for a list of

inoperative equipment if the main generator is/does

not reset.

Illumination of the STBY GEN light indicates that

standby generator power is not available for the

essential and emergency buses. The STBY GEN light

illuminates for standby generator system failure or

for failure of the essential bus relay(s). No bus loses

power if the STBY GEN light illuminates when the

main generator is still on line. The standby generator

may only be reset by depressing the ELEC CAUTION

RESET button.

Illumination of both STBY GEN and FLCS PMG

lights indicates that standby generator and FLCS

PMG power is not available. If the main generator

is on line, no buses lose power and the EPU does not

automatically activate.

T.O. GR1F16CJ1

344Change 1

Illumination of the MAIN GEN light

after a 23 second loss of power to the

HUD, MFD's, and other cockpit instru

ments indicates shorting failure of an

OCSC or other wiring/equipment.

NOTE

F

PX II

 The VHF radio is not powered

when the main generator is off line.

F

With standby generator failure and

the MAL & IND LTS switch in DIM,

the ELEC SYS caution light may not

appear to illuminate when the MAS

TER CAUTION and STBY GEN lights

illuminate.

If MAIN GEN light illuminated after a 23 second

loss of the HUD and MFD's was observed:

1.

Land as soon as practical.

If MAIN GEN light illuminated and a 23 second loss

of the HUD and MFD's was not observed, or if STBY

GEN or STBY GEN and FLCS PMG lights illuminate:

1.

ELEC CAUTION RESET button - Depress.

This action may reset the main or standby

generator. Cycling the MAIN PWR switch

may also reset the main generator; however,

this action momentarily removes standby

generator power and activates the EPU.

2.

Land as soon as practical.

Main and Standby Generator Failure (in Flight)

Illumination of the MAIN GEN and STBY GEN

lights indicates that power is lost from at least one

nonessential ac bus and that the standby generator

also failed. The EPU should start automatically at

the time of the second failure as indicated by the

EPU AIR and EPU run lights. Additional lights,

such as HYDRAZN, AVIONICS FAULT, and

ENGINE FAULT, may also illuminate. If both

generators fail, power to all essential and non

essential buses (ac and dc) is lost. Refer to

EMERGENCY POWER DISTRIBUTION, this sec

tion, for list of inoperative equipment. The EPU

generator powers the emergency ac and dc buses and

both battery buses. Depressing the ELEC CAUTION

RESET button may reset the main and/or standby

generator.

NOTE

PX II

 The VHF radio is not powered

when the EPU is running or the main

generator is off line.

If MAIN GEN and STBY GEN lights illuminate:

1.

EPU switch - ON (if EPU run light is off).

2.

ELEC CAUTION RESET button - Depress.

This action may reset the main and/or

standby generator. The MAIN PWR switch

may also be cycled to reset the main

generator.

If MAIN GEN or STBY GEN light goes off:

3.

EPU switch - OFF, then NORM.

4.

ADI - Check for presence of OFF and/or AUX

warning flags.

If warning flag(s) is in view, refer to EGI

FAILURE/TOTAL INS FAILURE, this section.

PX II

 If only AUX flag is in view, pitch

and roll attitude information is likely

to be erroneous due to INS autorestart

in the attitude mode when other than

straight and level, unaccelerated

flight conditions existed.

5.

Land as soon as practical.

6.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

If MAIN GEN and STBY GEN lights remain on:

3.

ADI - Check for presence of OFF and/or AUX

warning flags.

If warning flag(s) is in view, refer to EGI

FAILURE/TOTAL INS FAILURE, this sec

tion.

PX II

 If only AUX flag is in view, pitch

and roll attitude information is likely

to be erroneous due to INS autorestart

in the attitude mode when other than

straight and level, unaccelerated

flight conditions existed.

T.O. GR1F16CJ1

345

4.

Land as soon as possible.

5.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

6.

If hydrazine depletes or EPU run light goes off

at low thrust - Go to ABNORMAL EPU

OPERATION, this section.

After landing and aircraft is stopped:

7.

Chocks - Installed (or parking brake engaged).

8.

EPU switch - OFF.

If chocks are not installed, be prepared

to immediately engage the parking

brake if it disengages when the EPU is

shut off.

9.

MAIN PWR switch - MAIN PWR (until chocks

are installed).

Main, Standby, and EPU Generator Failure

A main, standby, and EPU generator failure is

indicated by illumination of the MAIN GEN and

STBY GEN lights without an EPU run light. Other

indications include loss of all avionics, ADI OFF and

AUX warning flags, and uncontrollable cold airflow

into the cockpit or reduced airflow to the cockpit if

the water separator coalescer freezes up, and 

PX III

loss of OBOGS. The caution lights which illuminate

for a failure of just the main and standby generators

(e.g., AVIONICS FAULT, ENGINE FAULT) do not

illuminate. Refer to EMERGENCY POWER DIS

TRIBUTION, this section, for a list of inoperative

equipment. The primary concerns during multiple

generator failures are maintaining power to the

FLCS and maintaining/regaining power to the

emergency buses.

PX III

 With a main, standby, and EPU

generator failure, OBOGS and the OXY

LOW warning light are inoperative.

Activate EOS if above 10,000 feet

cockpit altitude.

The EPU generator may be inoperative for several

reasons, two of which may be remedied from the

cockpit. If the EPU AIR light is off, the EPU may not

have received an automatic start command;

manually turning the EPU on may correct this

failure. If the EPU GEN, EPU AIR, and HYDRAZN

lights are illuminated but the EPU run light is off,

the EPU may be underspeeding. If the EPU PMG

light is on or blinking, EPU speed is very slow. The

underspeed could be caused by failure of hydrazine

to power the EPU in conjunction with a low thrust

setting and may be corrected by advancing the

throttle. If the EPU generator operates, refer to

MAIN AND STANDBY GENERATOR FAILURE (IN

FLIGHT), this section.

If the EPU generator is still inoperative and the

main and standby generators do not reset, power

cannot be restored to the emergency buses. The

aircraft battery supplies power to battery buses No.

1 and No. 2. As long as the ACFT BATT TO FLCS

light remains off, the EPU PMG and/or FLCS PMG

is supplying adequate FLCS power. The primary

concern is aircraft battery life for communications,

brakes, and hook. UHF communications are

available on the frequency in use at power loss with

UFC selected. BACKUP must be selected if a

frequency change is desired.

If the FLCS PMG light illuminates when the MAIN

GEN, STBY GEN, and EPU GEN lights are on, there

are two possible sources of FLCS power (EPU PMG

and aircraft battery). If the EPU PMG and ACFT

BATT TO FLCS lights are off, the EPU PMG is

supplying power to the FLCS whether the EPU run

light is on or off.

If the ACFT BATT TO FLCS light is on, the aircraft

battery is supplying power to the FLCS. The aircraft

battery supplies power for FLCS operation for 314

minutes (depending on state of battery charge) after

total generator failure. As the aircraft battery

depletes, the flight controls either become unrespon

sive or uncommanded maneuvers occur.

Imminent loss of electrical power to

the FLCS is indicated by increasingly

degraded flight control response and

uncommanded motions. Total loss of

FLCS power results in a pitching

motion and complete loss of control. At

high airspeeds, the pitching motion

could be excessive and interfere with

the ability to eject.

T.O. GR1F16CJ1

346

NOTE

If total loss of FLCS power occurs in the

landing configuration and near final

approach airspeed, the pitching mo

tion is gradual and in the noseup

direction for all configurations.

The ACFT BATT FAIL light indicates battery

voltage less than 20 volts. Brake operation is

doubtful during total generator failure with the

ACFT BATT FAIL light on. As aircraft battery

voltage continues to decrease, the capability to

operate the brakes, lower the hook, and deploy the

drag chute is lost. Lower the hook early since

significantly higher battery voltage is required to

lower the hook than is required to keep it fully

extended. Once lowered, the hook remains full down

well past the point at which the brakes are lost. An

approachend arrestment is recommended, if

conditions permit, because it is difficult to ascertain

brake operation. Relative intensity of the warning

and caution lights is not a positive indication of

battery voltage level.

If MAIN GEN, STBY GEN, and EPU GEN lights

illuminate:

PX III

 With a main, standby, and EPU

generator failure, OBOGS and the OXY

LOW warning light are inoperative.

Activate EOS if above 10,000 feet

cockpit altitude.

NOTE

PX II

 The VHF radio is not powered

when the EPU is running or the main

generator is off line.

1.

AOA - 12 degrees maximum (200 knots

minimum).

LEF's are inoperative and departure

susceptibility may be increased. Near 1g

flight, 200 knots should keep AOA less

than 12 degrees. Limit rolling maneuvers

to a maximum bank angle change of 90

degrees and avoid rapid roll rates.

2.

EPU switch - ON (if EPU run light is off).

3.

Climb if necessary.

4.

Throttle - As required to extinguish the

HYDRAZN light.

If EPU GEN light goes off:

5.

Go to MAIN AND STANDBY GENERATOR

FAILURE (IN FLIGHT), this section.

If EPU GEN light is still on:

6.

ELEC CAUTION RESET button - Depress.

This action may reset the main and/or

standby generator.

If both MAIN GEN and STBY GEN lights remain on:

7.

MAIN PWR switch - BATT, then MAIN PWR.

This action may reset the main generator.

If either MAIN GEN or STBY GEN light goes off:

8.

EPU switch - OFF, then NORM.

9.

Land as soon as possible.

10. Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

If MAIN GEN, STBY GEN, and EPU GEN lights all

remain on or all come on again:

F

Plan to land within 30 minutes to

insure adequate electrical power for

communications, brakes, hook, and

drag chute.

F

If the FLCS PMG and EPU PMG lights

are on in combination with the ACFT

BATT TO FLCS light, the aircraft battery

is powering the FLCS. With the aircraft

battery powering the FLCS in addition to

the battery buses, approximately 314

minutes flight time is available.

F

When the FLCS is powered by the

aircraft battery, remain alert for

degraded flight controls. At the first

indication of degraded response, re

duce airspeed and climb to safe

ejection altitude. Eject prior to com

plete loss of control.

8.

HOOK switch - DN.

9.

PX II

 CNI, 

PX III

 C & I knob - BACKUP.

10. Minimize UHF transmissions.

T.O. GR1F16CJ1

347

If conditions permit:

11. Land as soon as possible.

Fly airspeed for 11 degrees AOA approach

using fuel state when power was lost.

12. LG handle - DN. (Use DN LOCK REL button.)

If LG handle does not lower, select

BRAKES CHAN 2 and position ALT

FLAPS switch to EXTEND. 

PW 229

Nozzle remains closed resulting in

higher than normal landing thrust.

13. ALT GEAR handle - Pull (190 knots maximum).

S

Alternate LG extension can be used up to 300

knots; however, the NLG may not fully extend

until 190 knots. Time above 190 knots should

be minimized in case there is a leak in the

pneumatic lines.

S

WHEELS down lights and TO/LDG CONFIG

warning light function are inoperative.

Monitor LG handle warning light to verify

that LG is down.

F

NWS is not available following alter

nate LG extension.

F

Do not depress the ALT GEAR reset

button while pulling the ALT GEAR

handle. This action may preclude

successful LG extension.

F

Pulling the ALT GEAR handle with

normal system B hydraulic pressure

may result in system B hydraulic

failure within 15 minutes.

14. Consider an approachend arrestment, if

conditions permit. (Refer to CABLE ARREST

MENT, this section.)

15. Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

After landing:

16. Stop straight ahead and have chocks installed

(or engage parking brake).

17. MAIN PWR switch - MAIN PWR (until chocks

are installed).

EPU Malfunctions

UNCOMMANDED EPU OPERATION

Failures can occur which allow engine bleed air to

spin the EPU turbine even though the EPU has not

been commanded on. This may not be apparent if the

thrust level and amount of bleed air are such that the

EPU is turning above or below the speed range which

turns on the EPU run light. During uncommanded

EPU operation on bleed air, EPU speed varies directly

with throttle position. High thrust settings are likely

to result in EPU failure.
The EPU may also activate for reasons not apparent to

the pilot. Although this is not an EPU malfunction, it

may be interpreted as uncommanded EPU operation.
If uncommanded EPU operation on bleed air is

suspected:

NOTE

The nonessential dc buses and essen

tial dc bus may lose power. If so, this

results in loss of power to fuel boost

and transfer pumps, 

PX II

 VHF radio,

CARA, ECM, and FCR and power for

normal weapon arming/release in

cluding selective jettison.

1.

Throttle - Minimum practical thrust.

2.

Stores - Jettison (if required).

Only if required to maintain low thrust.

3.

Land as soon as possible.

If EPU is running with normal indications:

NOTE

F

The nonessential dc buses and essential

dc bus lose power. This results in loss of

power to fuel boost and transfer pumps,

PX II

 VHF radio, CARA, ECM, and FCR

and power for normal weapon arming/

release including selective jettison.

F

If the affected systems are required

for the safe recovery of the aircraft,

consider delaying/terminating EPU

operation until the systems are no

longer required.

4.

EPU - Leave running.

5.

Land as soon as possible.

6.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

T.O. GR1F16CJ1

348

ABNORMAL EPU OPERATION

Abnormal EPU operation after a normal start

command is indicated by one or more of the

following:EPU run light flashes, indicating EPU

operation in tertiary speed control mode; EPU run

light does not come on or goes off after initial

illumination, indicating sustained underspeed or

overspeed operation; EPU HYDRAZN light does not

go off or EPU fuel quantity continues to deplete when

the throttle is advanced to assure adequate bleed air,

indicating an EPU bleed air or fuel control system

problem.

When tertiary speed control is functioning, the EPU

run light alternately cycles on and off (one to three

times per second) as a function of EPU speed

fluctuating between the normal and slightly above

normal speed ranges. The MASTER CAUTION and

the EPU HYDRAZN lights may illuminate. Hydra

zine use occurs regardless of available engine bleed

air. The hydrazine supply depletes in approximately

10 minutes. After hydrazine depletion, the EPU

continues to operate with available bleed air on

tertiary speed control.

If tertiary speed control cannot control EPU speed

(constant overspeed), total EPU failure is immi

nent. Excessive voltage generated by the EPU

generator or its PMG is regulated by the

converter/regulators before going to the FLCC.

Other electrical and avionic equipment may be

damaged by the overvoltage condition. When EPU

failure occurs, FLCS power is provided by the FLCS

PMG, main generator, standby generator, or the

aircraft battery (whichever has the higher voltage).

Under some failure conditions, hydrazine may not

be available to the EPU or it may continue to deplete

even with adequate bleed air. If a hydrazine

malfunction or depletion occurs, landing must be

accomplished using an engine thrust setting

sufficient to maintain an adequate bleed air supply

to the EPU. Failure to maintain minimum engine

rpm can result in hydraulic pressure fluctuations or

electrical bus cycling. Advance throttle as required

to maintain adequate bleed air supply. (If the EPU

is the sole source of hydraulic pressure, the throttle

should be set so as to keep the EPU run light on

during mild flight control inputs.) This action may

result in a thrust level that is higher than required

for a normal straightin approach. Fully open

speedbrakes or a shallower than normal approach

may be required. A straightin approach followed by

an approachend arrestment is recommended.

If EPU was turned on for an ACFT BATT FAIL or an

FLCS RLY light:

1.

EPU switch - OFF, then NORM.

2.

Land as soon as possible.

3.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

If EPU was activated for other reasons:

1.

Throttle - As  required ( 

PW 229

 7580, 

129

GE

8290 percent rpm).

Keep thrust high enough to assure adequate

bleed air if EPU fuel usage continues above

PW 229

 80, 

129

GE

 90 percent rpm or if EPU

run light is flashing. If EPU fuel is depleted

or if EPU run light goes off at low thrust, set

throttle to keep EPU run light on.

2.

EPU FUEL quantity - Monitor.

3.

Land as soon as possible.

Make an approachend arrestment, if practi

cal, if EPU fuel depletes before landing or if

EPU run light goes off at low thrust settings.

Refer to CABLE ARRESTMENT, this sec

tion.

If PTO shaft or both hydraulic

systems are failed, underspeed of the

EPU results in loss of control. Do not

retard throttle completely to IDLE

until after touchdown.

If EPU underspeeds, electrical bus

cycling may affect brake operation. For

a missed engagement, attempt CHAN

1 then CHAN 2 brakes. If no braking is

available, consider going around for

another engagement or making a

departureend arrestment. The park

ing brake still operates.

4.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

T.O. GR1F16CJ1

Change 1349

FLCS RLY Light

Illumination of the FLCS RLY light indicates that

voltage on one or more of the four FLCC branches

connected to the aircraft battery is inadequate

(below 20V). Therefore, should main generator,

standby generator, and FLCS PMG power be lost

(engine shutdown, PTO shaft failure, ADG failure),

power would not be available to one or more FLCS

branches until the EPU is on line. The EPU must be

turned on if the FLCS RLY light cannot be

extinguished.

1.

FLCS PWR TEST switch - TEST, momen

tarily.

If FLCS RLY light goes off:

2.

Land as soon as practical.

If FLCS RLY light remains on:

2.

EPU switch - ON.

NOTE

F

The nonessential dc buses and essen

tial dc bus lose power. This results in

loss of power to fuel boost and transfer

pumps, 

PX II

 VHF radio, CARA, ECM,

and FCR and power for normal weapon

arming/release including selective

jettison.

F

If the affected systems are required for

the safe recovery of the aircraft,

consider delaying/terminating EPU

operation until the systems are no

longer required.

3.

Land as soon as practical.

4.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

If EPU runs abnormally:

3.

EPU switch - OFF, then NORM.

4.

Land as soon as possible.

Partial Electrical Power Loss

Loss of power to several systems or indicators without

any indications on the ELEC control panel may be the

result of wire harness chafing or the loss of power to

one or more ac or dc buses. Refer to EMERGENCY

POWER DISTRIBUTION, this section, to determine

affected buses and equipment. If one item on a bus is

powered, then that bus should be considered

powered. Wire harness chafing can affect numerous

items on more than one bus without causing loss of

power to a bus. 

A failed overcurrent sensing contactor (OCSC) may

be the cause of the partial power loss. If the OCSC

failure involves electrical shorting, power from the

main generator is degraded while the short is

present. An obvious effect of this degraded power is

loss of the HUD and MFD's. If the short quickly burns

itself open, only the system(s) which receives power

through the failed OCSC is lost. Power to the

nonessential ac No. 1, emergency ac No. 1, emergency

dc No. 1, and nonessential dc buses goes through one

OCSC. Failure of this OCSC results in a loss of power

to many items, including the FCR, CADC, stick trim,

TACAN, VHF radio, DED, FUEL FLOW indicator,

primary instrument and console lights, VVI, AOA

indicator, and 

PX II

 FCC. 

PX III

 The MMC enters a

degraded mode that includes loss of the HUD. Failure

effects for the other OCSC's are limited to individual

store stations, the FCR, or the nacelle ac buses. If the

short persists for 23 seconds, the main generator

goes off line and power is removed from all eight

overcurrent sensing contactors. The standby genera

tor should automatically come on line to power the

essential, emergency, and battery buses. Refer to

SINGLE GENERATOR FAILURES (IN FLIGHT),

this section if the MAIN GEN FAIL light is on.

OCSC's can also fail open without electrical

shorting. These failures do not result in degraded

power from the main generator but do cause loss of

power to the buses/items protected by the OCSC.

The ELEC CAUTION RESET button can be used to

reset a failed open OCSC; however, the OCSC may

not remain reset if the fault persists.

The buses with a resettable overcurrent sensing

contactor are nonessential ac bus No. 1 and the

nacelle nonessential ac bus.

The items with a nonresettable overcurrent sensing

contactor are the radar ac bus; stations 3, 5, and 7;

and left and right inlet stations.

1.

ELEC CAUTION RESET button-Depress.

The failed open OCSC may reset.

If power is restored:

2.

Land as soon as practical.

T.O. GR1F16CJ1

350Change 1

If power is not restored:

2.

Determine the power status of electrical buses.

Refer to EMERGENCY POWER DIS

TRIBUTION, this section, to determine the

power status of individual buses. If one item

on a bus is powered, then that bus should be

considered powered.

NOTE

Determining the status of the battery

buses is critical for a safe recovery of

the aircraft.

If one or both emergency ac buses are not powered:

3.

EPU switch-ON.

NOTE

F

The nonessential dc buses and essen

tial dc bus lose power. This results in

loss of power to fuel boost and transfer

pumps, 

PX II

 VHF radio, CARA, ECM,

and FCR and power for normal weapon

arming/release including selective jet

tison.

F

If the affected systems are required for

the safe recovery of the aircraft,

consider delaying/terminating EPU

operation until the systems are no

longer required.

If the battery buses 

PX III

 and emergency dc bus

No. 2 are not powered,:

4.

Consider a net arrestment, refer to NET

ARRESTMENT, this section.

If net arrestment is not available:

5.

Consider a gear up landing, refer to LANDING

WITH LG UNSAFE/UP, this section.

If power to the battery buses is lost after the

landing gear has been extended, the landing

gear cannot be raised.

6.

Refer to EMERGENCY POWER DISTRIBU

TION, this section.

7.

Land as soon as possible.

If EPU was activated:

8.

Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

Aircraft Battery Failure

Aircraft battery system failure is indicated by the

ELEC SYS and ACFT BATT FAIL lights. The FLCS

RLY light also illuminates if the failure involves low

battery voltage. If the battery fails and both main

and standby generators subsequently drop off line,

power is not available to activate the EPU. If the

battery fails and subsequent loss of main generator,

standby generator, and FLCS PMG power occurs

(e.g., engine shutdown, PTO shaft failure, ADG

failure), power is not available to activate the EPU

or control the aircraft. Thus, it is necessary to turn

the EPU on after battery failure is indicated. The

ACFT BATT FAIL light illuminates only for low

battery voltage while in flight (approximately 20

volts). If a battery charger failure occurs in flight and

is still present after landing, the ACFT BATT FAIL

light illuminates 60 seconds after WOW.

If the aircraft battery fails (and EPU is

off), do not taxi except to clear runway.

Subsequent loss of the main and

standby generators results in loss of all

braking, NWS, hook, radios, and drag

chute.

1.

EPU switch-ON.

NOTE

F

The nonessential dc buses and essen

tial dc bus lose power. This results in

loss of power to fuel boost and transfer

pumps, 

PX II

 VHF radio, CARA, ECM,

and FCR and power for normal weapon

arming/release including selective jet

tison.

F

If the affected systems are required for

the safe recovery of the aircraft,

consider delaying/terminating EPU

operation until the systems are no

longer required.

F

If both radios become inoperative after

an aircraft battery failure indication,

refer to PARTIAL ELECTRICAL

POWER LOSS, this section.

F

The ACFT BATT FAIL light may

subsequently extinguish. This should

not be interpreted to mean that the

battery has recharged. It may indicate

that the battery voltage is so low that

the light cannot remain illuminated.