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F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 45

T.O. GR1F16CJ1

375

Engine RPM and FTIT Response During

Spooldown and Airstart

ENGINE F100-PW-229

TIME SECONDS

100

200

400

600

800

1000

RPM %

FTIT C

350 KIAS

10,000 FEET

250 KIAS

35,000 FEET

350 KIAS

35,000 FEET

250 KIAS

10,000 FEET

25%

250/350 KIAS

35,000 FEET

250/350 KIAS

10,000 FEET

RATE OF ENGINE RPM AND FTIT DECAY

AS A FUNCTION OF ALTITUDE AND

AIRSPEED

At low altitude, regardless of airspeed,

the spooldown rate is rapid. Spooldown

rate is slower at higher altitudes as

airspeed is increased.

1F-16X-1-1040X

Figure 39.(Sheet 2)

T.O. GR1F16CJ1

376

NORMAL 25 PERCENT SPOOLDOWN AIRSTART ENGINE RPM AND FTIT

TIME TRACES FOR 250 KIAS/20,000 FEET

Light-off normally occurs within 5 seconds after the throttle is advanced to midrange.

However, engine rpm and FTIT turnaround are slow, making light-off subtle or difficult

to detect. Engine rpm stabilizes momentarily after light-off and FTIT may increase,

stabilize, or decrease as the engine rpm increases.

Engine RPM and FTIT Response During

Spooldown and Airstart

ENGINE F100-PW-229

THROTTLE TO MIDRANGE AT 25%

LIGHTOFF

THROTTLE TO OFF

TIME SECONDS

100

200

400

600

800

1000

1200

FTIT C

RPM %

1F-16X-1-1041X

25%

Figure 39.(Sheet 3)

T.O. GR1F16CJ1

377

THROTTLE TO MIDRANGE AT 50%

LIGHTOFF

THROTTLE TO OFF

100

200

400

600

800

1000

1200

FTIT C

RPM %

50%

NORMAL 50 PERCENT SPOOLDOWN AIRSTART ENGINE RPM AND FTIT

TIME TRACES FOR 250 KIAS/20,000 FEET

Light-off normally occurs within 5 seconds after the throttle is advanced to midrange.

However, engine rpm and FTIT turnaround are slow, making light-off subtle or difficult

to detect. Engine rpm stabilizes momentarily after light-off and FTIT may increase,

stabilize, or decrease as the engine rpm increases.

Engine RPM and FTIT Response During

Spooldown and Airstart

ENGINE F100-PW-229

TIME SECONDS

1F-16X-1-1042X

Figure 39.(Sheet 4)

T.O. GR1F16CJ1

378

NOTE

In most cases, the JFS will engage and

begin to arrest rpm spooldown rate at

approximately 30 percent. Engine rpm

should stabilize on the JFS at a

minimum of 22 percent.

PRI operation is confirmed by SEC

caution light not illuminated.

There are critical requirements which apply to any

airstart attempt. The most important is engine rpm.

High engine rpm provides the best chance of a

successful restart. Therefore, do not delay the

initiation of an airstart in an attempt to reach a

particular flight condition. Initiate an airstart as

soon as it becomes apparent that engine rpm has

decayed below inflight idle (approximately 60

percent rpm). Illumination of the ENGINE warning

light, engine instrument indications, and no

response to throttle movement can help confirm a

flameout. The best conditions for an airstart are at

30,000 feet MSL or below, 250 knots or more, and

high rpm. In general, the success of an airstart is

increased with higher engine rpm, lower altitude,

and higher airspeed.

The throttle should always be advanced to midrange

before 25 percent rpm regardless of FTIT, altitude,

airspeed, JFS assistance, or engine control mode to

prevent rpm decreasing below 12 percent. If rpm

decreases below 12 percent, fuel flow from the main

fuel pump and ignition power from the engine

alternator are lost allowing a further decrease in rpm.

As much as 350 knots or more is required to prevent

rpm from decreasing below 12 percent. If rpm is

allowed to decrease to near zero, 400 knots or more

may be required to regain 12 percent. This requires a

great amount of altitude which may not be available.

If rpm decreases to zero, a seized rotor may occur, due

to temporary engine thermal conditions, after which

it will not rotate even with high airspeeds or by

engaging the JFS. In general, rpm decay rate can be

decreased by increasing airspeed; however, below

30,000 feet MSL, higher airspeeds do not significant

ly affect the rpm decay. Therefore, maintain 250

knots below 30,000 feet MSL for spooldown airstarts.

This airspeed does not maintain rpm above 12

percent; however, it does the best tradeoff between

the rate of rpm spooldown and loss of altitude.

Stabilizing or increasing rpm is normally the first

indication of an engine lightoff. Lightoff normally

occurs within 5 seconds after advancing the throttle.

However, rpm turnaround is slow, making lightoff

subtle and difficult to detect. FTIT response is slow

and may reverse trend one or more times during the

start sequence. Neither condition should be confused

with a hung start.

DEEC overtemperature protection logic attempts to

limit FTIT to 870

C, which may result in decreasing,

hung, or slowly increasing engine rpm. If a hung start

occurs (stabilized FTIT 870

C or less, rpm stabilized

below 60 percent), increase airspeed to a maximum of

400 knots/0.9 mach if altitude allows. If hung start

continues or there is no throttle response, reinitiate

the airstart with the ENG CONT switch in SEC when

below 30,000 feet MSL.

During an SEC start, 4560 seconds is required for

engine lightoff and acceleration to midrange from

the time the throttle is advanced from OFF.

If a SEC airstart is initiated at high RPM (above 40

percent), as much as 30 seconds following throttle

advancement may be required for RPM to stabilize or

begin to increase, indicating a successful light. This

slow engine response should not be confused with a

nolight response in which case RPM would continue

to decrease.

SEC airstarts initiated at lower RPM show positive

RPM turnaround within 15 seconds of placing

throttle to midrange. RPM continuing to decrease

after 15 seconds from throttle advancement or

stabilizing at a minimum of 22 percent with the JFS

RUN light on, indicates a nolight has occurred.

High Altitude Airstart Considerations

PW 229

Refer to figure 39. At 30,000 feet MSL and above, the

airstart (PRI or SEC) should be initiated by retarding

the throttle to OFF then advancing to midrange as

soon as possible regardless of FTIT or airspeed.

Always advance the throttle to midrange by 25

percent engine rpm. Dive to obtain 400 knots/0.9

mach to minimize rpm spooldown rate and quickly

decrease altitude to less than 30,000 feet MSL. If

lightoff indications are not noted within 20 seconds

in PRI or 30 seconds in SEC after advancing the

throttle, or if FTIT exceeds 870

C, retard the throttle

to OFF and reinitiate the airstart with the ENG

CONT switch in

PRI,

NORM, regardless of

which control mode the engine is presently in. If a

hung start occurs (rpm stable with FTIT stable at

870

C or less), keep the throttle at midrange until

below 30,000 MSL then reinitiate the airstart with

the ENG CONT switch in SEC.

T.O. GR1F16CJ1

379

At high altitudes, the dive should be at approximately

30 degrees to gain or maintain 250 knots below 30,000

feet. Once established, approximately 510 degrees of

dive should maintain airspeed. Note that airspeed

should not be reduced to less than 250 knots until the

JFS RUN light is on, and PRI mode is confirmed.

Unless an airstart is obviously impossible (total lack

of fuel, engine seizure, etc.), do not become tempted to

establish a maximum range or maximum endurance

glide. The first consideration should be an immediate

spooldown airstart attempt even if the engine failed

for no apparent reason. If airstart airspeed is not

maintained, rpm decreases at a faster rate. The only

airstart option available is then a JFSassisted

airstart. Time constraints due to EPU fuel consump

tion must be considered. A maximum range or

maximum endurance glide from above approximately

35,000 feet may exhaust EPU fuel prior to landing.

(Refer to T.O. GR1F16CJ11, figure A63.)

The reason for most airstart failures above 30,000

feet MSL is the engine inability to light off and not

due to the DEEC's inability to control the start.

Therefore, all second airstart attempts above 30,000

feet MSL should be made with the ENG CONT switch

PRI,

NORM. The engine does not have a

lightoff problem below 30,000 feet; therefore, all

second airstart attempts below 30,000 feet MSL

should be made with the ENG CONT switch in SEC.

When below 20,000 feet MSL, select JFS START 2.

Activating the JFS above 20,000 feet is prohibited

since successful JFS start/motoring of engine is

unlikely and the brake/JFS accumulators will be

depleted. If the JFS RUN light is on and PRI mode is

confirmed, airspeed may be reduced to achieve

maximum range or maximum endurance. If the JFS

RUN light is on and SEC mode is confirmed,

maintain 250 knots minimum. With the JFS

running, EPU fuel consumption is also reduced.

Low Altitude Airstart Considerations

PW 229

Due to the limited time available and the rapid rpm

spooldown rate at low altitude, some additional

considerations are required. Below approximately

10,000 feet MSL, rpm decreases rapidly regardless

of airspeed and remains between 5025 percent for

only 510 seconds; therefore, rpm should be closely

monitored. Advance the throttle to initiate the

airstart before rpm goes below 25 percent

regardless of FTIT indication. This action should

insure that lightoff occurs prior to 12 percent rpm.

Start the JFS immediately after advancing the

throttle (if airspeed is below 400 knots).

Following a zoom climb, plan to arrive at 250 knots.

Airspeed may be reduced to achieve maximum

range or maximum endurance (200 or 170 knots,

respectively) only if PRI mode is confirmed and the

JFS RUN light is on. If SEC mode is confirmed or

tower shaft failure is suspected, maintain 250 knots

minimum. If a higher airspeed is maintained or an

attempt is made to gain airspeed to delay the rpm

decay, available time may be reduced to the point

that an airstart is not possible. During any low

altitude airstart attempt, constantly evaluate

altitude above the ground relative to airstart

success. Do not delay ejection below 2000 feet AGL

unless the engine is producing thrust capable of

maintaining level flight or safely controlling the

sink rate or unless a flameout landing can be

accomplished.

Airstart Procedures

PW 229

To perform an airstart, retard throttle to OFF,

then

advance throttle to midrange.

NOTE

If the throttle is retarded to OFF to clear

a stall, it should be maintained in OFF for

a few seconds to allow the stall to clear.

Start the JFS below 20,000 feet MSL and below 400

knots immediately after the throttle is advanced to

midrange to initiate the spooldown airstart.

If the JFS stops running or fails to run within 30

seconds, do not reattempt a JFS start until the

brake/JFS accumulators have time to recharge. Allow

1 minute of engine rotation (either windmilling or

JFS assisted) at 12 percent rpm or above to insure

that the brake/JFS accumulators are fully recharged.

Recharging begins 34 seconds before the JFS RUN

light illuminates or 30 seconds after selecting a start

position (in the event of a JFS failure to run).

Recharging begins regardless of JFS switch position.

In the event of a JFS shutdown, the JFS switch does

not relatch in either start position while the JFS is

spooling down. Spooldown from full governed speed

takes approximately 17 seconds. The JFS switch

must be cycled to OFF and then to START 2 to

reinitiate a JFS start. It is possible to complete the

spooldown before the brake/JFS accumulators are

recharged if the JFS ran for only a short time.

When the airstart is completed, turn the JFS off (if

tower shaft failure is not suspected). Reset the main

generator using the ELEC CAUTION RESET button

and verify MAIN GEN and STBY GEN lights are off.

Cycle the EPU switch to OFF, then back to NORM.

T.O. GR1F16CJ1

380Change 1

With engine failure or flameout,

OBOGS is inoperative. Activate EOS if

OXY LOW warning light illuminates

above 10,000 feet cockpit altitude.

To accomplish an airstart:

Throttle-OFF, then midrange.

NOTE

FTIT will decrease rapidly when

throttle is OFF.

Airspeed-As required.

Above 30,000 feet MSL, dive at 400

knots/0.9 mach. Below 30,000 feet MSL,

establish approximately 250 knots. When

below 20,000 feet MSL with the JFS RUN

light on and PRI mode confirmed, airspeed

can be reduced to achieve maximum range

or maximum endurance (

200 or 170,

205 or 175 knots, respectively, plus 5 knots

per 1000 pounds of fuel/store weights and

plus 5 knots if CFT's are installed).

NOTE

If maximum gliding range is not a factor,

consider maintaining 250 knots above

10,000 feet AGL to reduce rpm spooldown

rate (in case of JFS failure). Below 10,000

feet AGL with the JFS RUN light on and

PRI mode confirmed, maintain maximum

range or maximum endurance airspeed.

JFS switch-START 2 below 20,000 feet MSL

and below 400 knots.

NOTE

If the JFS switch is erroneously placed

to START 1, leave it there.

If the JFS RUN light does not illuminate

or goes off once illuminated, place the

JFS switch to OFF and reattempt

START 2 when the brake/JFS accumu

lators are recharged. The JFS switch

does not relatch in either start position

while the JFS is spooling down.

Stores-Jettison (if required).

If stores jettison is attempted after main

generator drops off line but before EPU

generator powers the SMS (approximately 5

seconds delay), stores will not jettison.

NOTE

Visually confirm the stores have

jettisoned and jettison again if re

quired.

If a no light, hot start, or stall occurs:

Throttle-OFF.

ENG CONT switch-SEC if below 30,000 feet

MSL (250 knots minimum).

NOTE

Place the ENG CONT switch to SEC

prior to placing the throttle to

midrange, otherwise a start anomaly

may result.

The proximity of the ENG CONT

switch to the JFS switch makes the

JFS switch susceptible to being

bumped to OFF when selecting SEC.

Throttle-Midrange.

If a hung start occurs:

Airspeed-Increase (maximum of 400 knots/

0.9 mach).

If hung start continues or there is no throttle

response:

Throttle-OFF when below 30,000 feet MSL.

10. ENG CONT switch-SEC (250 knots mini

mum).

NOTE

Place the ENG CONT switch to SEC

prior to placing the throttle to

midrange, otherwise a start anomaly

may result.

The proximity of the ENG CONT

switch to the JFS switch makes the

JFS switch susceptible to being

bumped to OFF when selecting SEC.

11. Throttle-Midrange.

If engine does not respond normally after airstart is

completed:

12. Refer to FLAMEOUT LANDING, this section.

T.O. GR1F16CJ1

Change 1381

If engine responds normally:

Do not turn JFS or EPU off if indicated

rpm is below 60 percent with adequate

thrust (e.g., tower shaft failure).

12. JFS switch-OFF.

13. ELEC CAUTION RESET button-Depress.

Verify MAIN GEN and STBY GEN lights are

off.

14. EPU switch-OFF, then NORM.

15. ADI-Check for presence of OFF and/or AUX

warning flags.

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

FAILURE, this section.

16. Throttle-As required.

NOTE

If the SEC caution light is on, refer to

SEC CAUTION LIGHT, this section.

17. Land as soon as possible.

18. Refer to ACTIVATED EPU/HYDRAZINE

LEAK, this section.

ENGINE MALFUNCTIONS

129

The EMS compares expected versus actual engine

operation. The purpose of the EMS MFL is to provide

maintenance personnel with an early indication of

an engine condition which requires correction. No

action is required for an engine MFL at anytime

during a flight.

Low altitude, for engine malfunction purposes, is

generally defined as 10,000 feet AGL or below. If an

engine malfunction is suspected, the initial reaction

should be to trade excess airspeed for altitude.

Unless

a suitable airfield is within gliding distance, turns

should be avoided as they decrease the amount of

time/altitude available to successfully recover engine

performance or prepare for ejection. Optimizing the

exchange of airspeed for altitude must be a priority

action for any engine malfunction. Above 310 knots,

more time is available by performing a zoom climb

using a 3g pullup to 30degree climb until

approaching the desired airspeed (use approximately

50 knots lead point) and then initiating a zerog

pushover. Below 310 knots and above the minimum

recommended ejection altitude, more time is

available by performing a constant altitude decelera

tion to the desired airspeed. If below the minimum

recommended ejection altitude and below 310 knots,

primary concern should be to trade excess airspeed

for altitude in preparation for ejection. If appropriate,

jettison stores as soon as possible.

For any situation where automatic activation of the

EPU is relied upon, verify that the EPU run light is

on to insure that the EPU has started. If the EPU run

light is off, position the EPU switch to ON.

SEC is a highly reliable backup engine operating

mode. However, in certain circumstances the engine

may malfunction in SEC following an auto transfer,

or continue to malfunction in SEC following a manual

transfer. Returning to PRI may result in proper

engine response, due to either the resetting of

internal hydromechanical control pressures or to the

resetting of digital engine control logic.

Idle thrust in SEC during ground operation is

approximately twice that in PRI. After landing in

SEC, consider minimizing taxi distance and consider

following HOT BRAKES procedures, this section.

Engine Fire

129

Generally, the first indication of fire in the engine

compartment is the ENG FIRE warning light.

Abnormal fuel indications (quantity/flow) may also

be present. FTIT probably will not be higher than

normal. Explosions, vibrations, or engine instrument

fluctuations are usually indicative of a serious engine

problem; engine failure may be imminent. Immediate

action should be taken to reduce thrust to the

minimum practical level after attaining safe ejection

parameters. If within gliding distance of a suitable

runway, consider shutting the engine down. Suffi

cient time should exist to analyze the situation and

make an ejection versus land decision. The ejection

decision should be based on visual and/or cockpit

indications that the fire is persisting. Cockpit

indications include continued illumination of the

ENG FIRE warning light and subsequent FLCS

malfunctions/degraded flight controls or subsequent

loss of either hydraulic system.

Fires can also occur in the nozzle area when using AB.

These fires are the result of portions of the nozzle

failing which allows the AB plume to burn through

the nozzle. Ventilation should inhibit forward

movement of the fire into and through the engine bay.

Since these fires are aft of the detection circuit, the

ENG FIRE warning light will not illuminate.

Additionally, the nozzle position indications are

normal, and there are no vibrations or instrument

fluctuations. In most cases, these ABrelated nozzle

T.O. GR1F16CJ1

382Change 1

fires are detected by someone outside the aircraft

(wingman, tower, etc.). When operating in AB and a

fire is reported at the rear of the aircraft, retard

throttle below AB immediately. This action should

extinguish a nozzle fire within approximately 3045

seconds and minimize damage to the aircraft skin,

speedbrakes, nozzle, and flight controls; however,

nozzle damage may result in a noticeable thrust loss.

If on takeoff and the conditions permit:

Abort.

If takeoff is continued:

Climb.

Maintain takeoff thrust until minimum

recommended ejection altitude is attained

and then throttle to minimum practical.

Stores-Jettison (if required).

At a safe altitude:

Throttle-Minimum practical.

If fire occurred in AB, ENG FIRE warning

light may not illuminate. Fire should

extinguish after throttle is retarded; how

ever, nozzle damage may result in lower than

normal thrust.

If ENG FIRE warning light goes off:

FIRE & OHEAT DETECT button-Depress.

Determine if fire detection circuit is

functional.

If fire persists:

Eject.

If fire indications cease:

Land as soon as possible.

OVERHEAT Caution Light

129

Detection of an overheat condition in the engine

compartment, ECS bay, MLG wheel wells, or EPU

bay illuminates the OVERHEAT caution light.

Accomplish as many of the following as required to

extinguish the light. If the light goes off, verify the

integrity of the detection circuit by depressing the

FIRE & OHEAT DETECT button and land as soon as

possible.

If OVERHEAT caution light illuminates:

Throttle-Minimum practical.

FIRE & OHEAT DETECT button-Depress.

Determine if fire detection circuit is

functional.

If OVERHEAT caution light remains on (or detect

circuit checks bad) and EPU is running:
3.

EPU switch-OFF (if feasible).

If the EPU was manually turned on, consider

turning it off to determine if it is the source

of the overheat condition. If the OVERHEAT

caution light remains on, the EPU should be

turned back on.

If OVERHEAT caution light remains on (or detect

circuit checks bad):
4.

OXYGEN-100%.

AIR SOURCE knob-OFF.

External fuel cannot be transferred in OFF

or RAM. Consider jettisoning tanks to

decrease drag if range is critical and the ECS

cannot be turned on for short periods of time

to transfer fuel.

With the ECS shut down or the AIR

SOURCE knob in OFF or RAM, the

gsuit does not inflate and PBG is

disabled.

Descend to below 25,000 feet and reduce

airspeed to below 500 knots.

When airspeed is reduced and cockpit is depressu

rized:
7.

AIR SOURCE knob-RAM (below 25,000

feet).

External fuel cannot be transferred in OFF or

RAM. Consider jettisoning tanks to decrease

drag if range is critical and the ECS cannot be

turned on for short periods of time to transfer

fuel.

With the ECS shut down or the AIR

SOURCE knob in OFF or RAM, the gsuit

does not inflate and PBG is disabled.

Nonessential electrical equipment-Off.

NOTE

If in VMC and the ADI and HSI are not

required for flight, the INS should be

considered nonessential.

Content .. 43 44 45 46 ..

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 45

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 45