Content .. 45 46 47 48 ..

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 47

T.O. GR1F16CJ1

390

The ENGINE warning light illuminates when

engine rpm is below 60 percent. Additionally, the

MAIN GEN and STBY GEN lights illuminate below

50 percent rpm and the EPU should start running.

Do not mistake a loss of ECS noise as an engine

flameout.

A flameout indicates an engine control failure, fuel

starvation, fuel system malfunction, or fuel cutoff

due to engine overspeed protection. If the engine

flames out, two features may instantly restart the

engine. There is an autorelight feature and the

capability to automatically transfer to SEC if certain

faults are detected in PRI. If these features work, the

restart may take place instantly and the flameout

may not be noticeable (except for the illumination of

the SEC caution light). In this situation, remain in

SEC. (Refer to SEC CAUTION LIGHT, this section.)

If the flameout progresses to the point that it is

noticeable, retard the throttle to OFF, then advance

to midrange. Refer to AIRSTART PROCEDURES

129

, this section.

Tower Shaft Failure

129

Failure of the engine tower shaft or its associated

geartrain results in engine flameout due to fuel

starvation. A restart is not possible; primary

emphasis should be on a flameout landing. If unable

to make a flameout landing, refer to EJECTION

(TIME PERMITTING), this section. Because tower

shaft failure results in the loss of rotation to the

enginedriven gearbox and ADG, the initial symp

toms are similar to main fuel pump failure. The

primary differences are that the rpm indication drops

immediately to zero and ENGINE warning light and

the SEC caution light illuminate since the engine

alternator is no longer providing power to the DEC.

The JFS should be started immediately upon

entering the JFS envelope to conserve EPU fuel. The

JFS drives the ADG and the engine gearbox which

restores rotation to both hydraulic pumps and

provides a reduced FLCS PMG output. Depending

on JFS performance and load, rpm may even be high

enough to restore standby generator power;

however, main generator power may cycle on and off.

Without the load of the engine, the JFS produces a

3055 percent rpm indication, which is the speed of

the engine gearbox and not the actual engine rpm.

The true engine rpm is unknown.

Low Altitude Engine Failure or Flameout

129

Refer to figures 310 and 311. Initial reaction to any

malfunction at low altitude should be to trade excess

airspeed for altitude. Higher altitude translates

directly to either additional time to achieve an

airstart or to additional glide range to reach a

suitable landing field. 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, more time is available by performing a

constant altitude deceleration to the desired

airspeed; if required, climb to achieve minimum

recommended ejection altitude.

If the zoom results in an altitude below 4000 feet

AGL, there may be insufficient time to achieve an

airstart prior to reaching minimum recommended

ejection altitude. In that case, primary consideration

should be given to preparing for ejection; do not delay

ejection below 2000 feet AGL.

If low altitude engine failure or flameout occurs:

Zoom.

Stores-Jettison (if required).

If stores jettison is attempted after main and

standby generators drop off line but before

EPU generator powers the SMS (approxi

mately 5 seconds delay), stores will not

jettison.

NOTE

Visually confirm the stores have

jettisoned and jettison again if re

quired.

Perform airstart (if altitude permits). Refer to

AIRSTART PROCEDURES, this section.

Below 4000 feet AGL, there may be

insufficient time to perform an airstart

prior to minimum recommended ejec

tion altitude.

AIRSTARTS

129

Refer to figure 312. Airstarting the engine does not

require exact airspeeds or rpm ranges, but there are

key events in the airstart sequence that must be

performed in a timely manner in order to have the best

chance for an airstart. The key events are initiating

the airstart while engine rpm is still high, selecting

SEC if there is no lightoff prior to rpm decaying below

50 percent in PRI (or immediately when below 10,000

feet AGL), and preserving engine rpm prior to

lightoff.

. GR1F

16CJ

391

160

180

200

220

240

260

280

300

320

340

360

380

400

420

440

460

480

500

INITIAL AIRSPEED KIAS

INITIAL AL

TITUDE 1000 FT AGL

1F-16X-1-4025X

GW = 23,000-25,000 LB

DI = 0-50

WINDMILLING OR SEIZED ENGINE

30-DEGREE CLIMB MAINTAINED TO 170/250 KIAS

CONFIGURATION:

CONDITIONS:

3G PULLUP TO 30

ZOOM CLIMB TO

ACHIEVE:

250 KIAS

170 KIAS

Low Altitude Zoom Capability

ENGINE F110-GE-129

DATA BASIS ESTIMATED

LG UP

Figure 310.

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

420

440

INITIAL AL

TITUDE 1000 FT AGL

MINIMUM RECOMMENDED

EJECTION ALTITUDE

30 DIVE TO DESCENT KIAS OR 3G PULLUP

TO 30 ZOOM CLIMB INITIATED FROM THE

AIRSPEED/ALTITUDE EXISTING AT FIRST

RECOGNITION OF ENGINE FAILURE

AIRSTART INITIATED AT START OF DIVE OR

ZOOM BY CYCLING THROTTLE TO OFF AND

THEN MIDRANGE

45 SECONDS ASSUMED AFTER

THROTTLE ADVANCE TO ACHIEVE

USABLE THRUST (ASSUMES AIRSTART

DESCENT AIRSPEED IS 170 KIAS

CONDITIONS:

ENGINE F110-GE-129

INITIAL AIRSPEED KIAS

(SEC) (JFS RUN LIGHT ON)

INITIATION AT 25 PERCENT RPM)

GR1F-16CJ-1-0120A37

Low Altitude Airstart Capability

DATA BASIS ESTIMATED

CONFIGURATION:

GW = 23,000-25,000 LB

DI = 0-50
LG UP

. GR1F

16CJ

392

Figure 311.

T.O. GR1F16CJ1

393

1F-16X-1-4024-1A

ENGINE F110-GE-129

0.2

0.4

0.6

0.8

1.0

1.2

1.4

MACH NUMBER

TITUDE 1000 FEET

JFS ENVELOPE

AIRSTART ENVELOPE

POINT B TO

SL = 8.5 MIN/44 NM

CONDITIONS:

DRAG INDEX = 0
KIAS = 250

NO WIND

MIN KIAS

(WITH JFS

OPTIMUM FLIGHT PATH DURING AN AIRSTART (TYPICAL)

Engine out descent flight path maintains the aircraft in the required airstart envelope.

A 30-degree dive to descent KIAS is used to approach the airstart envelope

(Point A to B).

DIVE

170 KIAS

Airstart is enhanced by increased airspeed, altitudes below 30,000 feet, and light-off

at highest possible engine rpm.

GW = 26,000 LB

400 KIAS/0.9 MACH

RUN LIGHT

ON)

250 KIAS

(RECOMMENDED)

Engine RPM and FTIT Response During

Spooldown and Airstart

Figure312.(Sheet 1)

T.O. GR1F16CJ1

394

1F-16X-1-4024-2X

TIME SECONDS

90 100

LIGHT-OFF

RATE OF ENGINE RPM AND FTIT DECAY AND RECOV-
ERY FOR SPOOLDOWN AIRSTARTS AT 25,000 FEET.

Following the rapid FTIT rise and peak after light-off, FTIT
slowly decreases approximately 50 C.

Airstarts initiated between 25-50 percent engine rpm are

slow to light-off and may take up to 90 seconds to regain

usable thrust.

TIME SECONDS

RPM %

FTIT C

800

700

600

500

400

300

200

900

LIGHT-OFF

100

LIGHT-OFF

RATE OF ENGINE RPM AND FTIT DECAY AND
RECOVERY FOR JFS-ASSISTED AIRSTART AT

Following the rapid FTIT rise and peak after light-
off, FTIT slowly decreases approximately 50 C.

Airstarts initiated between 25-50 percent engine

rpm are slow to light-off and may take up to 90
seconds to regain usable thrust.

20,000 FEET.

Figure312.(Sheet 2)

T.O. GR1F16CJ1

395

Oil pressure is directly related to rpm. Do not

confuse a low oil pressure indication due to

windmilling rpm as an oil system malfunction.

Factors such as altitude, airspeed, weather, etc.,

must be considered in determining whether to try

an airstart, to accomplish a flameout landing, or to

eject. Jettisoning stores reduces altitude loss

during an airstart and improves glide ratio during

flameout landing. If gliding distance is not a factor,

maintain 250 knots or more in order to reduce rpm

rate of decay until the JFS can be started. The

engine can be airstarted with airspeeds from

170400 knots/0.9 mach; however, 250 knots

provides the best tradeoff of altitude loss, range,

and airflow for the engine.

In flight, the throttle must be retarded to OFF then

back to the operating range for only four reasons: to

reset the overspeed protection logic, to clear a stall,

to begin the airstart procedure, or to terminate a

hot/hung start. Exact throttle position is not

important for an airstart, so any position between

IDLE and MAX AB is acceptable; however, the

midrange position is preferred because of possible

throttle misrigging at IDLE or possible engine

overspeed shutdown at MIL or above.

Once the throttle is retarded to OFF and then back

to the normal operating range, do not retard the

throttle to OFF again during the airstart unless a

hot/hung start occurs. Unnecessarily retarding the

throttle to OFF terminates any start attempt which

may be in progress.

A successful restart depends on many variables:

cause of flameout, type of fuel, altitude, airspeed,

and engine rpm when the airstart is attempted. High

engine rpm is the most important variable and

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 the airstart as soon as it becomes apparent

that engine rpm has decayed below inflight idle

(approximately 70 percent rpm) or illumination of

the ENGINE warning light, engine instrument

indications, and no response to throttle movement

confirm a flameout. The best conditions for airstart

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

with high engine rpm.

At medium and high altitudes, the airstart attempt

should be started in the engine control mode selected

by the DEC. The DEC contains diagnostic logic

designed to identify PRI engine control failures and

may automatically transfer to SEC. If there is no

indication of a lightoff before rpm decays below 50

percent, place ENG CONT switch to SEC (even if the

SEC caution light is on) and continue the airstart

attempt. At low altitude (below 10,000 feet AGL),

SEC should be selected as soon as possible after

initiating the airstart.

Of equal importance to selecting SEC when required

is preserving engine rpm. The JFS should be started

as soon as the aircraft is in the JFS envelope. The

advantage of using the JFS to assist the airstart is

that once the JFS RUN light is on, airspeed can be

reduced. Under normal conditions the JFS will

motor the engine at a minimum of 25 percent.

An airstart can be rapid if lightoff occurs above 60

percent rpm. Airstarts initiated between 5025

percent engine rpm are slow to light off and may take

up to 90 seconds to regain usable thrust. If altitude

is available, increasing airspeed can assist engine

acceleration and decrease the time to regain usable

thrust once a lightoff is achieved. As long as engine

rpm continues to increase, this condition should not

be considered as a hung/no start. Spooldown

airstarts initiated below 25 percent rpm have been

successful during flight tests, but spool up to usable

thrust may take more time than is available. Keep

engine rpm at 25 percent or above during spooldown

airstarts, if possible.

Following the rapid FTIT rise and peak of a lightoff,

FTIT slowly decreases approximately 50

C. There

fore, do not confuse a drop in FTIT as an unsuccessful

airstart unless accompanied by decreasing rpm as

well.

High Altitude Airstart Considerations

129

As altitude is increased above 30,000 feet MSL, the

probability of a successful airstart can be improved by

attempting the airstart as soon as possible (before

rpm decays below approximately 50 percent) and by

quickly descending to altitudes below 30,000 feet

MSL after the airstart is initiated. Airspeeds above

250 knots (400 knots/0.9 mach maximum) should be

considered as a means to reduce altitude and increase

the probability of a successful airstart. Spooldown

airstarts can be achieved with rpm as low as 25

percent, but not at all airspeeds and altitudes.

T.O. GR1F16CJ1

396Change 1

At high altitudes, dive as required to maintain speed

in the 250400 knot/0.9 mach range. Unless an

airstart is obviously impossible (total lack of fuel,

tower shaft failure, 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 fails for no apparent reason. If a

spooldown airstart is not successful before reaching

20,000 feet MSL, a JFSassisted airstart should be

attempted. When below 20,000 feet MSL, turn JFS

on. Activating the JFS above 20,000 feet MSL 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, airspeed

may 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). Time constraints due to EPU fuel

consumption must also be considered. A maximum

range or maximum endurance glide from above

approximately 35,000 feet MSL may exhaust EPU

fuel prior to landing. (Refer to T.O. GR1F16CJ11,

figure B63.) With the JFS running, EPU fuel

consumption is also reduced.

Low Altitude Airstart Considerations

129

Initiate the airstart as soon as possible. After

initiating a zoom climb and jettisoning stores (if

required), retard the throttle to OFF then advance

the throttle to the normal operating range. Place the

ENG CONT switch to SEC and turn on the JFS

(START 2) to assist the airstart.

Following a zoom climb, plan to arrive at 250 knots

until the JFS RUN light is on; airspeed may then 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). 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

129

To begin the airstart sequence, retard the throttle to

OFF; then immediately advance the throttle back into

the normal operating range, preferably 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.

After throttle advance, monitor for signs of a lightoff

before rpm decays below 50 percent (characterized

by a rapid rise in FTIT accompanied by a slow

increase in rpm). If rpm and FTIT continue to decay

after rpm drops below 50 percent, place the ENG

CONT switch to SEC (even if the SEC caution light

is illuminated).

If a hot/hung start occurs, retard the throttle to OFF

and allow the FTIT to drop to below 700

C before

advancing the throttle. Increasing the airspeed

(maximum of 400 knots/0.9 mach) should help the

next airstart to be cooler. If the condition persists,

retard the throttle to OFF, place the ENG CONT

switch to SEC, and allow the FTIT to decrease below

700

C before advancing the throttle.

After entering the JFS envelope, start the JFS to

assist in preserving rpm. With the JFS RUN light on,

airspeed may be reduced to achieve maximum

range/endurance.

If the JFS stops running or fails to run within 30

seconds, do not reattempt a JFS start until the

brake/JFS accumulators have had time to recharge.

Allow 1 minute of engine rotation (either windmil

ling or JFSassisted) 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 occurs 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 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.

It is possible the engine may not respond properly to

throttle movement following an otherwise success

ful airstart. If this occurs or if thrust is insufficient

to ensure a safe landing, switch to SEC, or if already

in SEC, switch to PRI.

T.O. GR1F16CJ1

Change 1397

When the airstart is completed and usable thrust is

regained, turn the JFS off. 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 and then back to

NORM.

NOTE

The VHF radio is not powered when

the EPU is running.

To accomplish an airstart:

Throttle-OFF, then midrange.

FTIT should decrease rapidly when

throttle is OFF. If FTIT does not

decrease rapidly, verify that the

throttle is OFF.

Do not mistake a rapid initial FTIT rise

during an airstart as an indication of a

hot start. Typically, airstarts are

characterized by rapidly increasing

FTIT with a slow increase in rpm.

If a relight does not occur before rpm decays below 50

percent or if below 10,000 feet AGL:

ENG CONT switch-SEC (even if SEC

caution light is on).

Airspeed-Attain approximately 250 knots or

establish maximum range or endurance

airspeed (

200 or 170,

205 or 175 knots,

respectively, plus 5 knots per 1000 pounds of

fuel/store weights) with JFS RUN light on.

Above 30,000 feet MSL, airspeeds in the

250400 knot/0.9 mach range should be

considered to reduce altitude and increase

the probability of a successful airstart.

NOTE

If maximum gliding range is not a

factor, consider maintaining 250 knots

or more above 10,000 feet AGL to

provide best restart conditions (in case

of JFS failure). Below 10,000 feet AGL

with the JFS RUN light on, maintain

maximum range or maximum endur

ance 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 accumulators 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 engine rpm rolls back or hangs below inflight idle

(approximately 70 percent) and FTIT exceeds 935

Throttle-OFF, then midrange.

Allow FTIT to drop below 700

C before

advancing the throttle.

Airspeed-Increase (400 knots/0.9 mach

maximum).

If hung start/hot start persists:

Throttle-OFF.

ENG CONT switch-SEC, if in PRI; PRI, if in

SEC.

NOTE

In certain circumstances, the engine

may malfunction in SEC. Returning to

PRI may result in attaining usable

thrust.

The proximity of the ENG CONT

switch to the JFS switch makes the

JFS switch susceptible to being

bumped to OFF when selecting SEC.

10. Throttle-Midrange.

Allow FTIT to drop below 700

C before

advancing the throttle.

Content .. 45 46 47 48 ..

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 47

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 47