UH60 AFCS

8/13/2019 UH60 AFCS

1/21

United States Army Aviation Warfighting Center

Fort Rucker, AlabamaJanuary 2008

UH-60ASTUDENT HANDOUT

UH-60A Automatic Flight Control System (AFCS)4748-6

PROPONENT FOR THIS STUDENT HANDOUT IS:

8/13/2019 UH60 AFCS

2/21

TERMINAL LEARNING OBJECTIVE:

ACTION: Identify operational characteristics of the UH-60A/L Automatic Flight Control System (AFCS).

CONDITION: In a classroom given appropriate training devices, a list of characteristics, TM 1-1520-237-10, TM1520-237-10CL, Aircrew Training Manual, and the student handout.

STANDARD: In accordance with (IAW ) TM 1-1520-237-10, TM 1-1520-237-10CL, Aircrew Training Manual,and the student handout.

SAFETY REQUIREMENTS: Use care when operating training aids and/or devices.

RISK ASSESSMENT LEVEL: Low

ENVIRONMENTAL CONSIDERATIONS:It is the responsibility of all soldiers and DA civilians to protect theenvironment from damage.

EVALUATION: You must answer 7 out of 10 questions correctly to receive a "GO" on this scoreable unit.

LEARNING STEP/ACTIVITY 1: Identify the functions and purpose of the Automatic Flight Control System(AFCS).

a Description The AFCS is an electromechanical or electrohydro mechanical servo system

8/13/2019 UH60 AFCS

3/21

(2) Dynamic stability (short-term stability) is the tendency to resist oscillation.

c. Reasons for system.

(1) Helicopters are not as stable as fixed-wing aircraft. External forces will cause any aircraft to changeattitude, airspeed, or heading. However, fixed-wing aircraft can be designed to return to the desired attitudewhen the external force is removed (static stability).

(2) Helicopters have little or no tendency to return to the desired attitude. Since the rotor head moves withthe aircraft, helicopter will assume a new attitude and not the desired one.

(3) A helicopter hangs under a rotor head (like a pendulum) and swings or oscillates under rotor head.

Dynamic stability prevents porpoise in pitch, rock in roll, and fishtail in yaw.

(4) Pilot workload is much higher in a helicopter than in a fixed-wing aircraft.

(a) Constant correction is required to maintain attitude, airspeed, and heading.

(b) Constant correction is required to minimize oscillation.

(c) Instrument flying is extremely difficult.

(d) Accuracy of weapons is very poor due to lack of stability.

(e) Passengers are uncomfortable because of lack of stability.

d. Purpose of the AFCS is to enhance the stability and handling qualities of the helicopter.

(1) It provides static stability by holding--

(a) Airspeed.

(b) Attitude.

(c) Heading.

(d) Coordination while turning

(2) It provides dynamic stability to prevent--

(a) Porpoising in pitch axis.

(b) Rocking in roll axis.

(c) Fishtailing in yaw axis.

(3) AFCS Breakdown

8/13/2019 UH60 AFCS

4/21

(d) FPS provides limited flight control positioning which assists in maintaining helicopter pitch and rollattitudes, airspeed, heading, and turn coordination.

LEARNING STEP/ACTIVITY 2: Identify the operational characteristics of the stabilator system.

a. Description. The helicopter has a variable angle of incidence stabilator to enhance handling qualities. Theautomatic mode of operation positions the stabilator to the best angle of attack for the existing flight conditions.

After the pilot engages the automatic mode, no further pilot action is required for stabilator operation. Twostabilator amplifiers receive airspeed, collective stick position, pitch rate, and lateral acceleration information toprogram the stabilator through the dual electric actuators.

b. Operation. The stabilator is programmed to--

(1) Align stabilator and main rotor downwash in low speed flight to minimize nose up attitude resulting fromdownwash.

(2) Provide collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.A collective position sensor detects pilot collective displacement and programs the stabilator for acorresponding amount of movement to counteract for pitch changes. This coupling of stabilator input forcollective displacement is automatically phased in between 30 and 60 KIAS

(3) Decrease angle of incidence with increased airspeed to improve static stability.

(4) Provide sideslip to pitch coupling to reduce susceptibility to gusts. When the helicopter is out of trim in aslip or skid, pitch excursions are also induced as a result of the canted tail rotor and downwash on the stabilator.Lateral accelerometers sense this out of trim condition and signal the stabilator amplifiers to compensate for thepitch attitude change (called lateral to sideslip to pitch coupling). Nose left (right slip) results in the trailing edgeprogramming down. Nose right produces the opposite stabilator reaction.

(5) Provide pitch rate feedback to improve dynamic stability. The rate of pitch attitude change of thehelicopter is sensed by a pitch rate gyro in each of the two stabilator amplifiers and is used to position the

stabilator to help dampen pitch excursions during gusty wind conditions. A sudden pitch up due to gusts wouldcause the stabilator to be programmed trailing edge down a small amount to induce a nose-down pitch todampen the initial support..c. Actuators (2).

(1) Description. Two identical stabilator actuators connected back to back.

(2) Purpose. Actuators serve to move the stabilator to the required position.

(3) Location. The Number 2 actuator connects to the helicopters tail pylon (top). The number 1 actuatorconnects to the stabilators upper surface.

(4) Operation. Each actuator contains an electric servo motor that responds to input signals by driving ascrewjack, which causes the actuator to extend or retract.

8/13/2019 UH60 AFCS

5/21

e. Position indicators (2).

(1) Description. Two identical stabilator position indicators allow the pilot and copilot to monitor stabilator

position.

(2) Location. The indicators, are located on the instrument panel (just below the pilot's and copilot'sAirspeed Indicators).

(3) Operation. They contain OFF flags that are removed from view when power is applied and an indicator

pointer that displays stabilator angles between 10up and 45down.

NOTE: Although the indicators are marked 10up and 45down, do not confuse this with the actual stabilator

travel of 9up and 39down.

f. Stabilator position placards.

(1) Description. These lighted decals show maximum airspeed in relation to stabilator position for stuckstabilator.

(2) Location. A lighted decal is located beside each stabilator indicator.

(3) Function. Decals serve to limit airspeed for varying stabilator angles. They are marked with degrees onthe left side and airspeed on the right side.

g. Amplifiers (2).

(1) Description. The two identical stabilator control amplifiers contain electronic components, pitch rategyros used in automatic stabilator control, and relays that allow manual control.

(2) Purpose. Stabilator control amplifiers provide lateral acceleration, airspeed discrete signals, and pitchrate signals to the SAS/FPS computer and automatic stabilator control and provide relays that allow manualcontrol of the stabilator.

(3) Location. Stabilator control amplifiers are mounted on the aft overhead cabin. The amplifier located onthe left side is identified as Number 1; the amplifier located on the right side is Number 2.

(4) Operation.

(a) The Number 1 amplifier provides control signals to the Number 1 actuator.

(b) The Number 1 stabilator control amplifier provides filtered lateral acceleration and airspeed discretesignals to the SAS/FPS computer. It also supplies airspeed discrete and filtered pitch rate signals to SASamplifier.

(c) The Number 2 stabilator control amplifier provides filtered pitch rate and filtered lateral accelerationsignals to the SAS/FPS computer. Each stabilator amplifier contains a pitch rate gyro that produces a DC signalproportional to the helicopters rate of pitch attitude change

8/13/2019 UH60 AFCS

6/21

(2) Purpose. Airspeed and air data transducers supply airspeed signals to the stabilator amplifiers for thestabilators automatic mode operation and the SAS/FPS computer.

(3) Location. Airspeed and air data transducers are located on the cockpit bulkheads (forward of and

below the instrument panel). The air data transducer is on the right side of the helicopter; the airspeedtransducer is on the left side.

(4) Operation. The airspeed transducer supplies an airspeed signal to the Number 1 stabilator controlamplifier. The air data transducer supplies airspeed signals to the Number 2-stabilator-control amplifier. Theair data transducer also supplies airspeed and pressure altitude signals to the command instrument system.Both transducers supply airspeed signals to the SAS/FPS computer and receive air pressure inputs from theinstrument pitot-static system.

i. Collective stick position transducer (2).

(1) Description. The two collective stick transducers are identical.

(2) Purpose. They supply DC collective stick position signals to the stabilator control amplifiers andSAS/FPS computer and from the Number 2 collective stick position transducer to the CIS processor.

(3) Location. Both transducers are mounted on the right side of the flight controls mixer assembly.

(4) O ti

8/13/2019 UH60 AFCS

7/21

(1) Description. The two lateral accelerometers are Identical.

(2) Purpose. They provide the stabilator control amplifiers with DC electrical signals that represent the

relationship of the helicopter bank angle to its turn rate.

(3) Location. The lateral accelerometers are mounted in the cabin ceiling. The Number 1 accelerometer islocated on the left side of the helicopter, and the Number 2 accelerometer is located on the right side. On someaircraft, they are located on the left and right sides of the stabilator amplifiers.

(4) Operation.

(a) The Number 1 accelerometer receives excitation from the left side of the helicopter and supplies

signals to the Number 1 amplifier.

(b) The Number 2 accelerometer receives excitation from the right side of the helicopter and providessignals to the Number 2 amplifier.

k. Control panel.

(1) Description. The stabilator/flight control panel contains switches and relays used to control thestabilator system.

(2) Location. The panel is located on the center of the lower console.

(3) Switches.

(a) Cyclic mounted stabilator slew-up switch. The preferred method of manually slewing the stabilatoris to use the cyclic mounted stabilator slew-up switch.

NOTE: Use of the cyclic mounted stabilator slew-up switch should be announced to the crew to minimizecockpit confusion.

(b) MAN SLEW. This switch is spring loaded to the center (OFF) lever lock switch. It allows the pilot toposition the stabilator to any fixed position within its full range of travel.

NOTE: Use of the MAN SLEW causes the AUTO control mode to disengage.

(c) AUTO control reset. An illuminated push-button switch displays the word ON when the stabilatorsautomatic control mode is engaged. Pushing the button resets the automatic mode if it fails.

NOTE: Airspeed transducers must be connected before the automatic mode will engage.

(d) Test button. The test button is operational at airspeeds below 60 knots and is used to ground checkthe stabilator system. It causes the stabilator to drive up and the AUTO mode to disengage. Relays in thecontrol panel cause the STABILATOR caution and master caution to illuminate and a beeping tone to besupplied to the pilot's and copilot's headsets when the AUTO mode is OFF. Pushing the master caution capsuleresets the master caution and tone.

8/13/2019 UH60 AFCS

8/21

WARNING: MAKE SURE ALL PERSONNEL AND EQUIPMENT ARE CLEAR OF THE STABILATOR BEFOREAPPLYING ELECTRICAL POWER TO THE HELICOPTER.

(a) The automatic mode disengages if positions of the stabilator actuators disagree by an amount that

depends on forward airspeed. Shutdown occurs at 10of error at 0 knots and 4of error at 150 knots.(b) The automatic mode also disengages when the MAN SLEW switch is moved to the UP or DN

position or the cyclic mounted stabilator slew up switch is used.

(2) Operation (general).

(a) Both stabilator amplifiers receive AC and DC power when electrical power is applied to thehelicopter. They, in turn, supply VDC to the airspeed and air data transducers, collective stick positiontransducers, lateral accelerometers, and actuator feedback potentiometers.

(b) Airspeed and air data transducers produce DC output signals that increase for forward airspeedsbetween 30 and 180 knots.

(c) Collective stick position transducers produce a DC output signal that is proportional to the collectivestick's position.

(d) A centered collective equals 0 volts. A down collective results in a positive signal; an up collectivecauses the output to go negative. (Output voltage is 1.34 volts per inch of stick displacement from the center.)

(e) Pitch rate signal.

1. Each stabilator amplifier contains a pitch rate gyro. These produce DC signals that representthe helicopters rate of pitch attitude change.

2. Pitch rate signals also are routed out of each stabilator amplifier through filters.

3. The number 1 signal is used by the SAS amplifier. The number 2 signal is used by the SAS/FPScomputer.

b. Manual mode operation.

(1) Manual mode operation allows the pilot to control stabilator position.

(2) The stabilator control/flight control panel stabilator MAN SLEW switch allows selection of any fixedstabilator position between 9 degrees (trailing edge up) and 39 degrees (trailing edge down). The switch hasfour sets of contacts. Two sets of "hot slew" contacts provide 28-VDC power to the Number 1 and Number 2stabilator control amplifiers anytime the switch is moved up or down. This output causes amplifier logic circuits

to disengage the automatic mode. The additional two sets of switch contacts supply 28 VDC to either slew upor slew down relays in both amplifiers. Contacts of the slew up or slew down relays supply the interlocks (28VDC) power to the actuator motors which cause the stabilator to drive. The pilot must never exceed the limitairspeed, listed on instrument panel placards, for any selected stabilator angle.

c. Degraded operation.

8/13/2019 UH60 AFCS

9/21

WARNING: COVERS ON PITOT TUBES WOULD CAUSE THE STABILATOR TO REMAIN IN THE TRAILING-EDGE DOWN POSITION WITH NO CAUTION LIGHTS OR AURAL WARNING.

LEARNING STEP/ACTIVITY 4: Identify the operational characteristics of the stability augmentation system

(SAS).

a. Analog stability augmentation system. The analog system (SAS 1) is one of two SAS systems. It operatesindependently of the SAS/FPS computer and provides the aviator with redundancy.

b. Digital stability augmentation system (SAS 2). SAS 2 is operated by the SAS/FPS computer. It isindependent of SAS 1 and provides stability in the same axis using the same actuators.

c. Purpose--provides dynamic stability in the pitch, roll, and yaw axes.

d. Components.

(1) Actuators (3).

(a) Description. Three actuators are provided for the pitch, roll, and yaw channels.

(b) Purpose. Actuators link SAS electronic components to the helicopters mechanical flight controlsystem.

(c) Location. The actuators are mounted on the transmission deck at the pilot assist servo.

(d) Operation.

1. Hydraulic pressure. An electrohydraulic servo control flapper valve allows 3,000 psi hydraulicpressure from the Number 2 hydraulic system, or backup system, to operate the actuator.

2. Electrical inputs. Electrical inputs are supplied by the analog SAS amplifier and digital SAS/FPScomputer. The actuators respond to electrical inputs and hydraulic pressure by moving control linkages that

change rotor blade angles without moving cockpit controls.

3. Actuator stroke. The actuator stroke is mechanically limited to allow maximum control authorityof 10 percent of the total control available to the pilot.

4. Lock pin. Each actuator contains a centering lock pin that locks the actuator output at midstrokewhen hydraulic pressure is removed.

8/13/2019 UH60 AFCS

10/21

(2) SAS Amplifier.

(a) Description. It contains a rate gyro that serves as a sensor for yaw SAS.

(b) Purpose. It processes aircraft sensor signals to develop command signals that are applied to SASactuators when SAS 1 is engaged.

(c) Location. The SAS amplifier is located on the floor of the electronic compartment's "tunnel" (belowthe instrument panel).

(d) Control authority. Amplifier electrical outputs are limited to allow analog SAS (SAS 1) a maximumof a 5-percent authority. Gain control circuits double each channel's gain when SAS 2 is switched OFF.

Authority remains at 5 percent.

(3) Sensors.

(a) No. 1 stabilator control amplifier supplies the SAS amplifier with filtered pitch rate, filtered and nulled

lateral acceleration, and airspeed discrete signals. The pitch rate signal originates from a rate gyro inside thestabilator amplifier. The airspeed discrete signal also is developed by the stabilator amplifier.

(b) The pilot's (Number 2) vertical gyro supplies the SAS amplifier with a signal that represents thehelicopters roll attitude.

(c) An airspeed transducer supplies a signal that determines polarity of the airspeed discrete.

8/13/2019 UH60 AFCS

11/21

(b) SAS 1 switch energizes the SAS amplifier for SAS 1 coils, and the SAS 2 switch energizes circuitry

in the SAS/FPS computer for SAS 2 coils.

(c) SAS 1 and SAS 2 each have a 5-percent authority for a total of a 10- percent authority.

(d) Failure of SAS 1 will not be indicated visually but may be known by the lack of aircraft stability.

(e) Failure of sensors controlling SAS 2 will cause the failure advisory panel on the flight control panelto illuminate.

(5) Indicators. In case of loss of actuator pressure, or if both SAS 1 and SAS 2 are off, the SAS OFFcaution will appear.

LEARNING STEP/ACTIVITY 5: Identify the operational characteristics of the digital automatic flight controlssystem (AFCS/SAS2).

a. Description. The digital AFCS will provide the following:

(1) Cyclic stick and pedal trim.

(2) Stability augmentation (SAS 2).

(3) Autopilot functions (FPS).

8/13/2019 UH60 AFCS

12/21

(c) Power. The computer is powered by the Number 2 AC primary bus and Number1 and Number 2

primary DC busses.

(2) Vertical gyros. Two vertical gyros, located in the nose electronic compartment, produce attitude signalsfor pitch and roll.

(3) ASN 43 compass system directional gyro. This gyro is located in the nose electronic compartment andproduces a heading signal.

(4) Airspeed and air data transducers.

(a) Location. These transducers are located in the forward section of the cockpit, above the tail rotor

pedals, with airspeed on the left side and air data on the right side.

(b) Operation. They operate from the pitotstatic system and are powered by the stabilator system.

(c) Signal use.

1. Yaw trim.

2. Pitch FPS--airspeed hold.

3. Yaw FPS--automatic turn coordination logic

4. Yaw SAS 2.(5) Rate gyros. Rate gyros in the pitch, roll, and yaw channels control the rate of any change.

(6) Lateral accelerometers. These are used to produce signals when the helicopter slips or skids.

(7) Collective stick position transducers. These are located at the flight controls mixer. They produce asignal that represents collective stick's position. The signals are used for yaw trim, collective to yaw coupling,

and pitch FPS airspeed hold.

(8) Drag beam switch/Weight on Wheels switch (WOW). This switch --

(a) Holds pitch, roll, and yaw integrators when helicopter is on ground.

(b) Prevents FPS from continuing to drive controls if aircraft is taxied to spot that is not level.

c. System's operation.

(1) Electrical supply. The SAS amplifier receives 115-VAC power from the AC essential bus. The SASamplifier and AUTO flight control panel engage circuits are supplied with 28-VDC essential bus. Operation ofroll SAS and yaw turn coordination is dependent on the pilot's (Number 2) vertical gyro. It is powered from the

AC essential bus. Pitch and roll channels receive signals from the Number 1 stabilator amplifier.

(2) Hydraulic supply. Hydraulic pressure, required for SAS actuator operation, is supplied by the Number 2

8/13/2019 UH60 AFCS

13/21

(b) SAS amplifier circuits modify the rate signal to provide desired aircraft and system response.

(c) SAS 1 gain depends on the engage condition of SAS 2. If SAS 2 is ON, SAS 1 operates at a normalgain. SAS 1 and SAS 2 supply the actuator with signals to stabilize the helicopter. If SAS 2 is OFF, the SAS 1

amplifier doubles its gain. This provides larger signals for a given aircraft movement to help compensate for theloss of SAS 2.

(d) The servo valve driver supplies current to operate the SAS actuator.

LEARNING STEP/ACTIVITY 6: Identify the operational characteristics of the trim system.

a. Trim actuators are connected to flight control linkages in a manner that allows them to move cockpit controls.

(1) Pitch--to fore and aft cyclic stick linkage.

(2) Roll--to lateral cyclic stick linkage.

(3) Yaw--to pedal linkage.

b. Pitch actuator is hydraulic.

(1) It receives 1,000 psi from pilot assist module.

(2) Pressure is supplied only if trim is ON and computer detects no pitch trim malfunction.

c. Roll and yaw actuators are electromechanical.

d. FPS provides 100 percent control authority using trim actuators.

e. All actuators operate at a limited rate (about 10 percent per second). They are self-limited and also limitedby computer.

f. All actuators contain override springs which--

(1) Allow pilot a 100-percent override of trim.

(2) Provide breakout and gradient forces at controls.

g. All actuators provide dampening.

(1) Force at controls is proportional to rate of movement.

(2) Small force is present during pitch and roll.

h. Roll and yaw actuators contain override clutches which--

(1) Allow override if electromechanical actuator jams.

8/13/2019 UH60 AFCS

14/21

(b) Actuator remains very close to trimmed position.

(c) Actuator holds the cyclic stick fixed.

j. Cyclic stick trim release button causes computer to release trim.

(1) Hydraulic pressure is removed from pitch trim actuator.

(2) Feedback signal is zeroed.

(3) Stick is free to move.

(4) Trimmed or referenced position becomes changed.

(5) Stick is trimmed to position where button is released.

(6) Cyclic stick trim switch changes computers command signal to actuator.

(a) Actuator will drive.

(b) Stick will drive at about 0.4 inches per second.

k. Roll trim actuator has a built-in servo system.

(1) System holds actuator and cyclic stick fixed when trim is ON and not released.

(2) It is referenced through clutches and centering springs in actuators when trim is OFF or released.

(3) Computer supplies command to the actuator when cyclic stick trim switch is used.

NOTE: When the cyclic trim switch is slewed left and right, while on the ground and with FPS on, the cyclic willreturn to center.

l. Yaw trim actuator has a built-in servo system.

(1) System holds actuator and pedals fixed when trim is ON and not released.

(a) It is referenced when yaw trim is released.

(b) Pedal microswitches release yaw trim at airspeeds less than 60 knots.

(c) Pedal microswitch and cyclic trim (pressed at the same time), is required to release yaw trim atairspeeds above 60 Kts. This disengages yaw trim and the turn coordination feature.

(2) Computer supplies command signal to yaw trim actuator and electronic collective to airspeed to yawcoupling (maximum effect below 40 knots, no effect above 100 knots).

(a) Boost servo pressure must be ON for proper operation.

8/13/2019 UH60 AFCS

15/21

(1) Pedals or cyclic stick become free in affected axis trim and FPS is inoperative.

(2) During pitch failure, actuator hydraulic pressure is removed.

(3) During roll or yaw failure, the actuator clutch is disengaged.

(4) Computer senses failure when actuator position signal (feedback) does not agree with command signal.

(a) Trim failure advisory light will be ON.

(b) Trim failure and flight path stabilization caution lights will be ON.n. Computer failure cause affected trim axis to shut down.

(1) Pitch channel. Flight indications are the same as for an actuator failure.

(2) Roll or yaw.

(a) Stick or pedals will be free.

(b) Trim failure and flight path stabilization caution lights will be ON.

(c) Computer (CPTR) failure advisory light will be ON.

(d) Trim and FPS in affected axis will be inoperative.

LEARNING STEP/ACTIVITY 7: Identify the operational characteristics of the flight path stabilization system(FPS).

a. It provides the autopilot functions, which are to --

(1) Hold roll attitude.

(2) Hold pitch attitude/airspeed.

(3) Hold heading or automatic turn coordination.

b. The flight path stabilization operates by trimming cockpit controls.

(1) Trim must be ON.

(2) Boost servos must be ON for proper yaw channel operation.

(3) There is a 100-percent control authority.

8/13/2019 UH60 AFCS

16/21

d. Pitch channel provides attitude hold (below 60 Kts) and attitude & airspeed hold (above 60 Kts)(airspeed holdoverrides attitude hold), by trimming cyclic stick to position required to maintain pilots desired attitude andairspeed..

NOTE: Airspeed hold goes OFF for 30 seconds after collective stick is moved through the 60-percent positionbelow 100 knots.

e. Yaw channel provides heading hold or automatic turn coordination/automatic turn logic by driving pedals asrequired to maintain pilots desired heading or balanced flight. It holds heading unless pedal trim is released orautomatic turn coordination/automatic turn logic is engaged.

(1) Pedal trim is released when airspeeds are less than 60 knots by pedal microswitches or whenairspeeds are greater than 60 knots by pedal microswitches and the cyclic trim release.

(2) Automatic turn coordination/automatic turn logic operates only at airspeeds above 60 knots andengages when the pilot slews (by use of the cyclic stick trim switch) left or right about inch and a roll attitudeof about 1.5 degrees or more.

f. FPS failures.

(1) Directional gyro failure disables heading hold.

(a) Pedal trim and automatic turn coordination remains functional.

(b) Flight path stabilization caution light is ON.

(c) Gyro failure advisory light is ON.

(2) Airspeed sensor failure disables automatic turn coordination.

(a) Flight path stabilization caution light is ON.

(b) Airspeed failure advisory light is ON.

(3) Lateral accelerometer failure disables automatic turn coordination.


(b) ACCL failure advisory light is ON.

(4) Vertical gyro (roll) failure.


(b) Gyro failure advisory light is ON.

(5) Yaw rate gyro failure.

8/13/2019 UH60 AFCS

17/21

8/13/2019 UH60 AFCS

18/21

DIGITAL AUTOMATIC FLIGHT CONTROL UNITS EFFECTS OF MALFUNCTIONS

8/13/2019 UH60 AFCS

19/21

D-27

STABPOS

DEG

STABPOS

DEG

STABILATOR SYSTEM

AIR DATATRANSDUCER

AIRSPEED

TRANSDUCER

COLLECTIVE STICKPOSITION TRANSDUCERS(on MechanicalMixing Unit)

#2 LateralAccelerometer

#1LateralAccelerometer

L/Spitottube

R/Spitottube

0 30

Miscompare Range Chartairspeed

stabilatoractuatorposition

100

PilotCopilot

(Used for checks & rigging)

MANSLEW: Sprungto off position, selects manual mode

when movedup or down,alows manual positioning ofstabilator to any position.

TEST: Functions@ 60KTS& below, signals #1amp.

to retracts #1 actuator, fault monitoring detects miscompare(IAW rangechart) between #1/#2 actuators and switches

to manual mode (audible & visual warnings activate).

AUTOCONTROL: Switches from manual to automatic mode.

CYCLICSLEW: Selects manual mode& moves stab.up only.(stabilator up movement stops whenswitch is released)

(canbemovedwithbatterypower viaDCESSbus)

(moves only whenconvertedpower ispresent via#2 DCPRI bus)

to

bothstab.

amps.

USE OF EXCHANGED A/S SIGNALS

80 KTS or LESS: Amps usehigher of thetwo A/S signals.

80KTS & ABOVE: Eachampuses it's own A/S signal.(if oneamp is sensing below 80 with theother sensing

above 80, thelow oneprograms for80 KTS)

PNL

LTS

PNLLTS

#2 Stab.Amp.

pitch rategyro

#1 Stab.Amp.

pitch rategyro

STABILATORCONTROLS

MANSLEW

UP

DN

OF

F

TEST

AUTOCONTROL

R

ESE

TAUTOFLIGHTCONTROL

ON

ON

ON ON ON

ON

SAS1 SAS 2 TRIM FPS

FAILURE ADVISORYRE

SE

T

RE

SE

T

BOOST

POWER ONRESET

CPTRSAS 2

TRIM RGYR

ACCL CLTV

A/S GYRD

STABILATOR

9 deg

39 deg

0 deg

150

4

RANGEOF MOTION

both actuators: @48 deg.

singleactuator: @ 35deg.(may be lessdependingonstabposition whenother actuatorwaslost)

Stab positionLimit & A/Ssignals

NO.1 ACTUATOR

NO.2ACTUATOR

2

1

position commands

position & limit feedback

ver 1.1

11/00

0

8/13/2019 UH60 AFCS

20/21

D-27

GYRO

COMP RATE

AIRSPEED

TRIMACT

V E RT D IRSAS

VALVE

COLLSTICK

LATACCEL

FANFAIL

PROC A

GND

NORM

PROC B

FANTEST

J139

J12

J111J121

FPS

TRIM

SAS 2

fault monitoring / advisory

STABILATOR CONTROLS

MAIN SLEW

UP TEST

AUTOCONTROL

RESET

SAS 1 SAS 2 TRIM FPS

OFF ON

ON ON ON ON

RESET

RESET

ON

BOOST FAI LU RE A DV IS ORY

CPTR

TRIM

SAS2

RGYR

ACCL

A/S

CLTV

GYRO

POWERON RESET

TRIM FAIL FLT PATH

STAB

SENSORS

1

2

3

Input sensor B,I,M,P, and Q

1 SAS2 sensor signals: Q,G,J,K,N,O,H,and R

2 TRIM sensor signals: E and B

3 FPS sensor sign als: B,E,J,K,N, and O

NOTE: signals A,F,L,M, and R arefor fault monitoring only

Automati c Fl ight Contro l Input sig nals

A air da ta transducer s ignal J #2 pitch rate gyro si gnal (#2 stab amp )B air speed transducer signal K heading signal (gyro magnetic compass)C #1 lateral accelerometer signal L pilots vert. gyro pitch signal (att. ind. sys.)D #2 lateral accelerometer signal M pilots vert. gyro roll signal (att. ind.sys.)E #1 collect ive posit ion sensor N copilots vert. gyro pitch signal (att . ind. sys.)F #2 collect ive posit ion sensor O copilots vert. gyro rol l signal (att .ind.sys.)G rol l rate gyro s ignal P #1 yaw rate gyro s ignal (f rom sas ampl if er )H #2 yaw rate gyro signal Q #1 f i ltered lateral acceleromtere signal (#1 stab amp)I #1 pitch rate gyro signal (#1 stab amp) R #2 filtered lateral acceleromtere signal (#2 stab amp)

FLIGHT PATH STABILIZATION SYSTEMver 1.110/97

8/13/2019 UH60 AFCS

21/21

D-31

2

1

GYRO

COMP RATE

AIRSPEED

TRIMACT

VERT DIRSAS

VALVE

COLLSTICK

LATACCEL

FANFAIL

PROCA

GND

NORM

PROCB

FANTEST

J139

J12

J111J121

FPS

TRIM

SAS 2

fault monitoring / advisory

#2 Stab.

Amp.

pitch rate

gyro

#1 Stab.

Amp .

pitch rate

gyro

STABILATOR

STABILATOR SYSTEM

SIGNALS IN

# 1 CLTV# 1 ACCL

A/S X-DUCTER

SIGNALS IN

# 2 CLTV# 2 ACCL

A/D X-DUCER

SIGNALS OUT SIGNALS OUT

#1 CLTV

#1 ACCLA/S X-DUCER

PITCH RATEGYRO

#2 CLTV

#2 ACCLAIR DATA

PITCH RATEGYRO

TEST FAULTMONITORING

CIRCUIT

TEST FAULTMONITORING

CIRCUIT

TESTDRIVE/ ACT ONLY

STABILATOR CONTROL PANEL

STAB. MODE SELECT (AUTO)STAB. MAN. SLEWSTAB. TEST

SAS / FPS SYSTEM

SIGNALS IN#1 PITCH RATE GYRO#2 VERTICAL GYRO#1 ACCL.

A/S X-DUCER

SAS 1

AMP.

YAW RATE

GYRO

PITCH

ROLL

YAW

PITCH RATE GYRO

VERTICAL GYRO

#1 ACCL.

A/S X-DUCER

YAW RATE GYRO

TRIM ACTUATORS

PITCH ROLL YAW

#1 AND #2 ACCL (FILTERED)AIR DATA X-DUCERYAW RATE GYRO

NOTE:

#1 AND #2 ACCLFILTERED SIGNALS ARE

PROCESSED IN THE STABILATOR AMP ROLL RATE GYRO

#2 PITCH RATE GYRO

PILOT'SCYCLIC ANDPEDAL TRIM

CONTROLSWITCHES

SIGNAL OUT

(COPILOT'S) #1 VERTICAL GYRO

#1 ACCL.#1 CLTVA/S X-DUCER

#1 PITCH RATE GYRO

ASN 43 COMPASS(HEADING)

SASACTUATORS

SIGNALS OUT

#1 CLTVA/S X-DUCER

TRIMSIGNALS IN

Documents

UH60 AFCS