AFCS

Question 1

The Automatic Flight Control System (AFCS) enhances the stability and handling qualities of the helicopter. It is comprised of four basic subsystems:

Answer 1

Stabilator

Stability Augmentation System (SAS)

Trim

Flight Path Stabilization (FPS)

Question 2

The AFCS subsystems provide the helicopter with:

Answer 2

Static and dynamic stability.

AFCS provides oscillation damping (dynamic stability) and maintains desired attitude, speed, and handling (static stability).

Question 3

The collective stick position transducers are ……………… and are located on the right side of the …………………………….. as you face forward on the aircraft.

Answer 3

The collective stick position transducers are identical and are located on the right side of the mechanical mixing unit (MMU) as you face forward on the aircraft.

Question 4

How many collective stick position transducers are there?

Answer 4

Unmodified UH-60 A aircraft have two

all other aircraft UH-60 A+/L have three

Question 5

Collective position sensors detect …………………… and ………………….. the stabilator a corresponding amount to counteract pitch changes.

Answer 5

Collective position sensors detect pilot collective displacement and program the stabilator a corresponding amount to counteract pitch changes.

Question 6

Stabilator Actuator Miscompare Thresholds

Answer 6

30 KIAS allows 10⁰

150 KIAS allows 4⁰

Question 7

Stabilator actuator miscompare Airspeeds and angles

Answer 7

30 kias: up to 10 deg

150 kias: up to 4 deg

Question 8

Stabilator Auto Mode light is on when:

Answer 8

In the auto mode with no faults

Question 9

When is stabilator fault monitoring occuring?

Answer 9

All the time

Question 10

4 requirements for the stabilator to be in the Auto Mode:

Answer 10

Collective Interlock

Airspeed/Airdata 1.7V

No Miscompare (30KIAS allows 10 deg/ 150 KIAS allows 4 deg)

No Hot Slew (Cyclic or MAN Slew)

Question 11

How many limit switches are in the stabilator system

Answer 11

8 total

• 4 in Coffee can
• 4 in stabilator actuators (2 ea actuator)

Question 12

Collective stick position transducers supply ………………….. position signals to the ……………………or …………………… to position the stabilator based off of the movement of the collective.

Answer 12

They supply collective stick position signals to the stabilator amplifiers or dual stabilator controller (DSC) to position the stabilator based off of the movement of the collective.

Question 13

AFCS Sensors (inputs)

Answer 13

Lateral Accelerometers

Airspeed Transducer

Air Data Transducer

Pitch Rate Gyro

Vertical Gyro

Collective Position Sensors

Question 14

AFCS Pricessors (brains)

Answer 14

1/#2 Stabilator Amplifiers or Dual Stabilator Controller

AFCS Computer

SAS 1 Amplifier

Question 15

AFCS Actuators (muscle)

Answer 15

Trim Actuators

SAS Actuators

Stabliator Actuators

Question 16

When the stabilator (SCALP) Streamlines it…

Answer 16

Streamline- Align stabilator and main rotor downwash in low-speed flight to minimize nose-up attitude resulting from rotor downwash.

Question 17

When the stabilator (SCALP) Collective Couples it…

Answer 17

Collective Coupling- Provides collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.

Question 18

When the stabilator (SCALP) provides collective coupling it…

Answer 18

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

Question 19

When the stabilator (SCALP) angle of incidence varies it…

Answer 19

Angle of Incidence- Decrease angle of incidence as airspeed increases to improve static stability

Question 20

When the stabilator (SCALP) provides lateral sideslip to pitch it…

Answer 20

Lateral Sideslip (pitch)- Provide (lateral) sideslip to pitch coupling to reduce susceptibility to gusts.

LEFT PEDAL- Stabilator will drive 3 degree down from its original reference. Correcting for more Main Rotor down wash placing ACFT in a nose up attitude.

RT PEDAL- Stabilator drives up from the original reference. Correcting for less main rotor downwash placing the aircraft nose down.

Question 21

When the stabilator (SCALP) provides pitch rate feedback it…

Answer 21

Provides pitch rate feedback to improve dynamic stability.