Functions of the Stabilator

Instructor:

CW2 Scott Paul Rogers

STABILATOR

TLO: To reinforce basic system fundamentalsfor the UH-60 IPC.

STABILATOR SYSTEM

The Stabilator is a variable angle of incidence airfoilthat enhances aircraft handling qualities in the pitchaxis. The system performs both static and dynamicstability.

STABILATOR SYSTEM

ACTUATORS

AIRSPEEDSENSORS

AM

PL

IFIE

RS

ACCELEROMETERS

POSITIO

N

INDICATORS

STABILATOR ACTUATORS

• Identical Actuators• Tail Pylon• Position the Stabilator• Screw Jack Drive• D/C ESS BUS (#1)

# 2

#1

STABILATOR AMPLIFIERS

• Identical Amplifiers• Aft Overhead Cabin• Pitch Rate Gyros• Auto/ manual control# 1

# 2

AIRSPEED SENSORS

• Airspeed transducer• Air data transducer• Cockpit bulkheads• DC signal 30-180 knts• Signal to Stab Amps

AIRSPEED

AIR DATA

LATERAL ACCELEROMETER

• Bank to turn rate• DC signal to amplifier• Mounted in cabin

COLLECTIVE POSITION TRANSDUCERS

• On mixing unit• Forward #1 amplifier• DC signal to amplifier

#2#1

POSITION INDICATORS

CYCLIC MOUNTED STABILATOR SLEW SWITCH

STABILATOR CONTROL PANEL

STABILATOR

5 FUNCTIONS

STABILATOR FUNCTIONS

Align stabilator and main rotor down wash in low speed flight to minimize nose-up attitude resultingfrom downwash.

STABILATOR FUNCTIONS

Decrease angle of incidence with increased airspeedto improve static stability.

STABILATOR FUNCTIONS

Provide collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.

STABILATOR FUNCTIONS

Provide side slip to pitch coupling to reducesusceptibility to gusts or out of trim condition.

STABILATOR FUNCTIONS

Provide pitch rate feedback to improve dynamicstability

EMERGENCY PROCEDURES

AUTO MODE FAILURE

1. Cyclic mounted stabilator slew-up switch - Adjust if necessary to arrest nose down pitch rate.

AUTO MODE FAILURE

2. AUTO CONTROL switch - Press ON once.

AUTO MODE FAILURE

If automatic control is not regained:3. Manually slew stabilator - Adjust to 0 for

flight above 40 KIAS or full down when airspeed is below 40 KIAS. The preferred method of manually slewing the stabilator up is to use the cyclic mounted stabilator slew-up switch.

4. LAND AS SOON AS PRACTICABLE.

AUTO MODE FAILURE

If manual control is not possible:

5. STAB POS indicator - Check and fly at or below KIAS LIMITS shown on placard.

6. LAND AS SOON AS PRACTICABLE.

UNCOMMANDED NOSE DOWN

1. Cyclic - Adjust as required.

2. Collective - Maintain or increase.

3. Cyclic mounted stabilator slew-up switch - Adjust as required to arrest nose down pitch rate.

UNCOMMANDED NOSE DOWN

4. MAN SLEW switch - Adjust to 0 at 40 KIAS and full down at airspeeds below 40 KIAS.

UNCOMMANDED NOSE DOWN

5. LAND AS SOON AS PRACTICABLE.

UNCOMMANDED NOSE UP

1. Cyclic - Adjust as required.

2. Collective - Reduce as required.

UNCOMMANDED NOSE UP

4. MAN SLEW switch - Adjust to 0 at 40 KIAS and full down at airspeeds below 40 KIAS.

UNCOMMANDED NOSE UP

5. LAND AS SOON AS PRACTICABLE.

WARNINGS

If the airspeed fault advisory light is illuminated, continuedflight above 70 KIAS with the stabilator in the AUTO MODEis unsafe since a loss of the airspeed signal from the remainingairspeed sensor would result in the stabilator slewing full-down

WARNINGS

If acceleration is continued or collective is decreased withthe stabilator in a trailing edge down position, longitudinalcontrol will be lost. The stabilator shall be slewed to 0 above 40 KIAS and full-down when airspeed is less than40 KIAS.

WARNINGS

Pressing the AUTO CONTROL RESET button after afailure occurs results in the automatic mode coming onfor one second. If a hardover signal to one actuator ispresent, the stabilator could move 4 to 5 in that one secondbefore another auto mode failure occurs. Subsequentreset attempts could result in the stabilator moving toan unsafe position.

WARNINGS

If the stabilator AUTO mode repeatedly disengages duringa flight, flight above 70 knots is prohibited with the stabilatorin to AUTO mode.

QUESTIONS?