Content .. 15 16 17 18 ..

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 17

T.O. GR1F16CJ1

1120

TRAILING EDGE FLAPS (TEF'S) (FLAPERONS)

The flaperons are located on the wing trailing edge

and function as ailerons and TEF's. The flaperons

have a maximum command deflection of 20 degrees

down and 23 degrees up. When acting as flaps, the

deflection is downward; when acting as ailerons, the

deflection is up or down, as commanded. Both

functions are operable whenever the FLCS is

powered. The TEF's are controlled as a function of the

LG handle position, the ALT FLAPS switch, airspeed,

and mach number. Positioning the LG handle to DN

or the ALT FLAPS switch to EXTEND causes the

TEF's to deflect downward. At all airspeeds below 240

knots, the TEF's position is 20 degrees down. Above

240 knots, the TEF's reduce deflection as a function

of airspeed until nearly/fully retracted at 370 knots.

ALT FLAPS Switch

The ALT FLAPS switch is located

on the FLCP,

on the LG control panel. With the switch in

NORM, the TEF's are controlled by the LG handle

and airspeed. Placing the switch to EXTEND lowers

the TEF's only, depending on airspeed. The ALT

FLAPS switch does not affect the operation of the

LEF's unless the FLCS is operating on standby gains.

Refer to STANDBY GAINS, this section.

FLIGHT CONTROL SYSTEM (FLCS)

Refer to figure 142 for FLCS functional schematic

and figure 143 for FLCS pitch, roll, and yaw

schematic. The FLCS is a digital fourchannel,

flybywire system which hydraulically positions

control surfaces. Electrical signals are generated

through a stick, rudder pedals, and a MANUAL

TRIM panel. A main component of the FLCS is the

flight control computer (FLCC). Redundancy is

provided in electronic branches, hydraulic systems,

power supplies, and sensor systems. A FLT

CONTROL panel (FLCP) provides a BIT RUN FAIL

light and controls.

Command signals to the FLCC are initiated by

applying force to the stick and rudder pedals. These

signals are processed by the FLCC along with signals

from the AOA sensors, air data system, flight control

rate gyros, accelerometers, and INS. The processed

signals are transmitted to the ISA's of the horizontal

tails, flaperons, and rudder which are positioned to

give the commanded response.

Pitch motion is controlled by symmetrical movement

of the horizontal tails. Roll motion is controlled by

differential movement of the flaperons and horizontal

tails. Yaw motion is controlled by the rudder. Roll

coordination is provided by an ARI. The ARI function

is not available whenever MLG wheel speed exceeds

60 knots or if AOA exceeds 35 degrees. After takeoff,

ARI is activated within 2 seconds after the LG handle

is raised (spin down braking system). If the LG

handle remains down, 1020 seconds are required for

the MLG wheels to spin down and activate ARI.

Digital Backup (DBU)

DBU provides a software backup in the event of

software problems in the primary program. The DBU

is a reduced set of control laws which automatically

engages when software problems in the FLCC force a

majority of the branches into a failed state. DBU can

only be disengaged by use of the DIGITAL BACKUP

switch.

DBU operation does not significantly impact aircraft

handling qualities during normal cruise operation or

landing.

During DBU operation:

The AOS feedback function is inoperative.

Autopilot, terrain following, and stick steering are

inoperative.

Gun compensation is not provided.

With the LG handle in DN, the TEF's are positioned

to 20 degrees down. With the LG handle in UP and

the ALT FLAPS in EXTEND, the TEF's are

positioned to 20 degrees down if airspeed is less

than 290 knots.

There is no roll rate input to the AOA limiter.

Maximum roll rate command is a constant 167

degrees per second.

STORES CONFIG switch is inoperative.

Stick commands are essentially CAT III limited.

Rudder pedal commands are essentially CAT I

limited.

Dual air data failures are not recognized in DBU.

Standby gains are not engaged. If the LG handle is

in UP, midvalue air data is always selected. If the

LG handle is in DN, gains are fixed at normal

landing values.

Pitch trim centering at wheel spinup is inopera

tive.

AOA indications do not set to zero and random AOA

indications are possible in gusty wind conditions

with NLG WOW.

T.O. GR1F16CJ1

1121

The STICK CONTROL switch and the override

feature of the paddle switch are inoperative. If MPO

is activated, it cannot be overridden in the other

cockpit.

LEF scheduling is simplified and optimized for a

cruise condition at approximately 20,000 feet MSL.

LEF are not commanded to 2 degrees up when MLG

wheel speed is greater than 60 knots and the

throttle is IDLE or if MLG WOW.

DBU does not support communication on the MUX

bus, so failures while in DBU are not reported.

FLCS LIMITERS

Refer to figure 144 for limiter values. FLCS limiters

are provided in all three axes to help prevent

departures/spins.

AOA/G Limiter

Refer to figure 145. In cruise gains, the AOA/g limiter

reduces the positive g available as a function of AOA.

The negative g available is a function of airspeed.

Below 15 degrees AOA, the maximum positive g

available is +9g. As AOA increases, the maximum

allowable positive g decreases. The positive g limit

and maximum AOA depend on the position of the

STORES CONFIG switch. In CAT I, positive g

decreases to a value of 1g at 25 degrees AOA.

Maximum commanded AOA is approximately 25.5

degrees. In CAT III, maximum AOA varies from

approximately 1618 degrees as a function of GW and

The negative g available above approximately 250

knots is -3g. Below 250 knots, the available negative

g varies between 3g and zero g as a function of

airspeed, altitude, and AOA.

In takeoff and landing gains, the STORES CONFIG

switch has no effect on limiting or gains. Maximum

positive g is a function of airspeed and AOA. The

negative g command limit is not a function of

airspeed. It is a fixed limit. The maximum AOA for 1g

is approximately 21 degrees.

In inverted or upright departures, the AOA/g limiter

will override stick pitch commands if the MPO is not

engaged. The MPO can always override the negative

g function of the limiter. It can also override the AOA

function of the limiter when the AOA exceeds 35

degrees. Refer to MPO, this section.

Roll Rate Limiter

In cruise gains, the roll rate limiter reduces available

roll rate authority to help prevent roll coupled

departures. This authority is reduced as airspeed

decreases, AOA increases, or trailing edge down

horizontal tail deflection increases. Roll authority is

further reduced for large total rudder commands. In

takeoff and landing gains, roll rate limiting is

available but is a fixed value independent of AOA,

airspeed, or horizontal tail position.

Rudder Authority Limiter

In cruise gains, the rudder authority limiter reduces

the pedal commanded rudder deflection as a function

of AOA, roll rate, and STORES CONFIG switch

position for departure protection. However, ARI

authority, stability augmentation, and trim authority

are not reduced. In takeoff and landing gains,

category I rudder authority limiting is provided.

Yaw Rate Limiter

When AOA exceeds 35 degrees, the yaw rate limiter

overrides pilot roll and rudder commands and

provides flaperon with and rudder against the yaw

rate until AOA is below 32 degrees to enhance spin

resistance. The yaw rate limiter provides no

protection against yaw departures in the normal

flying range (-5 to 25 degrees AOA).

When AOA decreases below -5 degrees and airspeed

is less than 170 knots, the yaw rate limiter engages

but does not affect pilot roll and rudder commands.

Pilot roll and rudder commands are inhibited during

inverted departures only when the MPO is engaged.

The yaw rate limiter provides rudder against the yaw

rate until AOA is above -5 degrees to enhance spin

resistance.

Automatic yaw rate limiting to enhance spin

resistance is independent of the angleofsideslip

feedback function; thus, limiting is available even if

the FLCS AOS FAIL PFL is present.

FLCS GAINS

During normal operation, the FLCS receives inputs

(gains) from the ADC and provides relatively

constant aircraft response for a given stick input,

regardless of altitude or airspeed. This response

varies slightly depending on configuration. In the

event of a dual air data failure, the FLCS switches to

standby (fixed) gains.

T.O. GR1F16CJ1

1122

GR1F16CJ100441X37

FLCS Functional Schematic (Typical)

COMMANDS

TRIM INPUTS

MANUAL PITCH

FLCS POWER INPUTS

CONTROL INPUTS

RATES

ACCELERATION

AIRFLOW

AIR DATA

SWITCHES

BIT INDICATION

MANUAL TRIM PANEL

TRIM CONTROLS

TRIM/AP DISC

MANUAL PITCH OVERRIDE

SWITCH PANEL

DC POWER FLCS

QUADRUPLE FORCE

SENSORS

QUADRUPLE RATE

SENSORS

QUADRUPLE

ACCELEROMETERS

DUAL AIRFLOW SENSORS

PNEUMATIC SENSOR

ASSEMBLY (PSA)

CENTRAL AIR DATA

COMPUTER (CADC)

AIR DATA

Cockpit

BIT

Side Panel

Stick

Override

Stick

Rudder Pedals

Roll

Pitch

Yaw

Normal

Lateral

AOA

Total Pressure

Static Pressure

AOA

Total Pressure

Static Pressure

Total Temperature

Static Pressure

AIRCRAFT MANUAL TRIM

3-AXIS COMMANDS

TEF COMMAND

AOA

FLIGHT CONTROL PANEL

PITCH TRIM CENTERING

CONVERTER/REGULATORS

SIDESLIP DIFFERENTIAL

PRESSURE SENSOR

Figure 142.(Sheet 1)

T.O. GR1F16CJ1

1123

GR1F-16CJ-1-0044-2A37

WARNING and CAUTION

LIGHTS

DMUX

MFD FLCS PAGE

PFL'S

MEMORY MODE

SENSOR POWER AND TEST

RIGHT HORIZONTAL TAIL

INTEGRATED

SERVOACTUATOR (ISA)

RUDDER

INTEGRATED

SERVOACTUATOR (ISA)

LEFT FLAPERON

INTEGRATED

SERVOACTUATOR (ISA)

RIGHT FLAPERON

INTEGRATED

SERVOACTUATOR (ISA)

LEFT HORIZONTAL TAIL

INTEGRATED

SERVOACTUATOR (ISA)

DUAL LEF COMMAND

SERVOS

LEGEND:

ELECTRICAL

MECHANICAL

LEF ACTUATION

SYSTEM

FLIGHT CONTROL COMPUTER

STABILITY/COMMAND

AUGMENTATION

QUADRUPLE ELECTRONICS/

PROCESSORS

CONTROL DYNAMICS

GAIN SCHEDULING

QUADRUPLE INPUT/

OUTPUT SELECTORS

800 HZ SENSOR POWER

SUPPLY

AILERON-RUDDER

INTERCONNECT

STRUCTURAL FILTERS

AOA LIMITING

YAW RATE LIMITING

HIGH AOA ROLL RATE

LIMITING

DIGITAL BACK-UP

AUTOPILOT

AUTO TF

SIDESLIP FEEDBACK

AMUX

MFL'S, PFL'S

INS PITCH, ROLL,

CADC-ALTITUDE

INERTIAL VELOCITIES

YAW ANGLES;

NVP-TF COMMANDS

FCC, MMC-

PX III

PX II

Figure 142.(Sheet 2)

T.O. GR1F16CJ1

1124

PITCH

ROLL

PITCH TRIM

MECHANICAL LIMIT

HORIZONTAL TAIL STICK FORCE

AOA

PITCH RATE

NORMAL ACCELERATION

IMPACT PRESSURE

ROLL TRIM

AILERON STICK FORCE

ROLL RATE

GUN FIRE

ISA

RIGHT HORIZONTAL

TAIL

MECHANICAL LIMIT

LEFT HORIZONTAL

TAIL

RIGHT

FLAPERON

LEFT

FLAPERON

FLIGHT
CONTROL
COMPUTER

1F-16X-1-4009X

FLCS gains scheduled by air

data inputs.

NOTES:

FLCS Pitch, Roll & Yaw Schematic (Typical)

ISA

ELECTRICAL

MECHANICAL

LEGEND:

GUN COMPENSATION

INS

Sideslip angle and rate

calculated in the FLCC

based on INS inputs.

YAW

YAW TRIM

RUDDER PEDAL FORCE

YAW RATE

LATERAL ACCELERATION

MECHANICAL LIMIT

RUDDER

ISA

ANGLES AND VELOCITIES

Figure 143.

T.O. GR1F16CJ1

1125

FLCS Limiter Functions

PITCH AXIS

ROLL AXIS

YAW AXIS

Maximum AOA=25

Maximum roll rate command

decreases with:

AOA above 15

Maximum deflection (pedal com

mand) reduced for:

AOA>14

(zero roll rate)

CAT

g command system until 15

AOA

Airspeed less than 250 knots

Horizontal tail deflection more

than 5

trailing edge down

Total rudder command (from

Roll rate>20

/sec

NOTE:

Zero rudder authority available at

AOA

g/AOA command system above

AOA

Total rudder command (from

pilot and FLCS) exceeding 20

Combination of horizontal tail

greater than 15

trailing edge

down and AOA above 22

Maximum AOA=16

(de

pending on GW)

Maximum roll rate command

reduced by approximately 40 per

cent of CAT I authority. Additional

Maximum deflection (pedal com

mand) reduced for:

CAT

III

g command system until 7

AOA

at 100 knots to 15

AOA at 420

knots and above

cent of CAT I authority. Additional

decreases as function of AOA, air

speed, horizontal tail position,

and total rudder command

AOA>3

(zero roll rate)

Roll rate>20

/sec

NOTE:

g/AOA command system above

these values

NOTE:

Zero rudder authority available at

AOA

1. In takeoff/landing gains, the

FLCS operates as a pitch rate

command system until 10

AOA and a pitch rate/AOA

command s stem abo e 10

1. In takeoff/landing gains, maxi

mum roll rate is fixed at

approximately onehalf the

maximum roll rate available in

cr ise gains regardless of

1. Above 35

AOA, the yaw rate

limiter provides yaw axis

antispin control inputs

2. Below 5

AOA and less than

NOTES

command system above 10

AOA

2. +9g available until 15

AOA.

Maximum g decreases as a

function of AOA and airspeed

cruise gains, regardless of

AOA, airspeed, or horizontal

tail deflection

2. Above 35

AOA, the yaw rate

limiter cuts out stick roll com

2. Below 5 AOA and less than

170 knots, the yaw rate limiter

provides antispin rudder in

puts; pilot roll and rudder com

mands are cut out only when

MPO is engaged

u c o o O a d a speed

mands and provides roll axis

antispin control inputs

g g

3. Maximum deflection (30

)

always available thru ARI and

stability augmentation

Figure 144.

T.O. GR1F16CJ1

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1F-16X-1-0010X

NORMAL LOAD F

ACTOR G

AOA DEGREES

CAT III SELECTED

GW = 25,000 POUNDS

CAT III SELECTED

GW = 30,000 POUNDS

CAT III SELECTED

GW = 35,000 POUNDS

CAT I SELECTED

AOA/G Limiter Function (Cruise Gains)

Figure

145.

T.O. GR1F16CJ1

Change 11127

Cruise Gains

The FLCS is in cruise gains with the LG handle in UP,

the ALT FLAPS switch either in NORM or in

EXTEND above 400 knots, and the AIR REFUEL

switch either in CLOSE or in OPEN above 400 knots.

At low AOA, the pitch axis of the FLCS is a g

command system. As AOA increases, the FLCS

switches to a blended g and AOA system to provide a

warning of high AOA/low airspeed. Roll rate limiting

is available and maximum roll rate decreases as a

function of low airspeed, high AOA, and horizontal

tail position.

Takeoff and Landing Gains

The FLCS is in takeoff and landing gains with the LG

handle in DN, the ALT FLAPS switch in EXTEND

(below 400 knots), or the AIR REFUEL switch in

OPEN (below 400 knots). In takeoff and landing

gains, the FLCS pitch axis operates as a pitch rate

command system until 10 degrees AOA and a blended

pitch rate and AOA command system above 10

degrees AOA. Roll rate limiting is available but is a

fixed value independent of AOA, airspeed, or

horizontal tail position.

Standby Gains

In standby gains, control response is tailored for a

fixed altitude (sea level, standard day) and airspeed

(LG handle in UP, approximately 600 knots; LG

handle in DN, approximately 230 knots). The FLCS

warning light and FLCS FAULT caution light

illuminate.

When operating on standby gains, the LEF's are at

zero degrees with the LG handle in UP and the ALT

FLAPS switch in NORM. The LEF's deflect 15

degrees down with the LG handle in DN or the ALT

FLAPS switch in EXTEND. The operation of the

TEF's is not affected in standby gains.

A standby gains condition can be reset in flight, back

to the first failure condition, by using the FLCS

RESET switch. The original air data system failure is

latched upon occurrence of the second failure and

does not reset. If reset is successful, the FLCS

warning light goes off.

FLCS DATA RECORDER

The FLCS data recorder is attached to the ejection

seat and departs the aircraft on ejection. It retains the

same information as the FLCC including FLCS

failure data, airspeed, altitude, true heading and

elapsed time from takeoff.

ANGLEOFSIDESLIP (AOS) FEEDBACK FUNC

TION

The angleofsideslip feedback function provides

improved departure prevention by using AOS and

AOS rate feedback to position the rudder. AOS and

AOS rate are calculated in the FLCC using INS data.

The calculated AOS is also monitored in the FLCC by

comparing it to an AOS derived from differential

pressure sensor signals. This monitoring detects one

of two possible failures:

AOS derived from INS is erroneous.

AOS derived from differential pressure sensor is

erroneous.

Either failure deactivates the AOS feedback function

and activates the FLCS FAULT caution light and the

FLCS AOS FAIL PFL.

The AOS feedback function is active when all of the

following conditions are met:

Airspeed is less than 350 knots.

AOA is greater than 10 degrees.

AOS exceeds 2 degrees.

AOS monitoring has not detected a failure.

DBU is not engaged.

MPO switch is in NORM.

The FLCS is in cruise gains.

Terrain following is not engaged.

GUN COMPENSATION

The FLCS automatically compensates for the off

center gun and the aerodynamic effects of gun gas

emissions during firing by moving the flaperons and

rudder. Gun compensation is optimized for 0.70.9

mach range; therefore, all excursions may not be

eliminated. For example, gunfiring at low mach may

result in nose left excursions while nose right

excursions are likely at higher mach. Failure

monitoring of gun compensation circuits is not

provided and there are no caution light indications for

incorrect compensation.

FLIGHT CONTROL SYSTEM (FLCS) CONTROLS

Stick

Refer to figure 146. The stick is a forcesensing unit

which contains transducers in both pitch and roll

axes, moves approximately 1/4 inch in both axes, and

is rotated slightly cw.

Content .. 15 16 17 18 ..

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 17

F16C/D (BLOCKS 50 AND 52+). FLIGHT MANUAL (15 OCTOBER 2002) - page 17