AFCS Flashcards
The Automatic Flight Control System (AFCS) enhances the stability and handling qualities of the helicopter. It is comprised of four basic subsystems:
Stabilator
Stability Augmentation System (SAS)
Trim
Flight Path Stabilization (FPS)
The AFCS subsystems provide the helicopter with:
Static and dynamic stability.
AFCS provides oscillation damping (dynamic stability) and maintains desired attitude, speed, and handling (static stability).
The collective stick position transducers are ……………… and are located on the right side of the …………………………….. as you face forward on the aircraft.
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.
How many collective stick position transducers are there?
Unmodified UH-60 A aircraft have two
all other aircraft UH-60 A+/L have three
Collective position sensors detect …………………… and ………………….. the stabilator a corresponding amount to counteract pitch changes.
Collective position sensors detect pilot collective displacement and program the stabilator a corresponding amount to counteract pitch changes.
Stabilator Actuator Miscompare Thresholds
30 KIAS allows 100
150 KIAS allows 40
Stabilator actuator miscompare Airspeeds and angles
30 kias: up to 10 deg
150 kias: up to 4 deg
Stabilator Auto Mode light is on when:
In the auto mode with no faults
When is stabilator fault monitoring occuring?
All the time
4 requirements for the stabilator to be in the Auto Mode:
Collective Interlock
Airspeed/Airdata 1.7V
No Miscompare (30KIAS allows 10 deg/ 150 KIAS allows 4 deg)
No Hot Slew (Cyclic or MAN Slew)
How many limit switches are in the stabilator system
8 total
- 4 in Coffee can
- 4 in stabilator actuators (2 ea actuator)
Collective stick position transducers supply ………………….. position signals to the ……………………or …………………… to position the stabilator based off of the movement of the collective.
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.
AFCS Sensors (inputs)
Lateral Accelerometers
Airspeed Transducer
Air Data Transducer
Pitch Rate Gyro
Vertical Gyro
Collective Position Sensors
AFCS Pricessors (brains)
1/#2 Stabilator Amplifiers or Dual Stabilator Controller
AFCS Computer
SAS 1 Amplifier
AFCS Actuators (muscle)
Trim Actuators
SAS Actuators
Stabliator Actuators
When the stabilator (SCALP) Streamlines it…
Streamline- Align stabilator and main rotor downwash in low-speed flight to minimize nose-up attitude resulting from rotor downwash.
When the stabilator (SCALP) Collective Couples it…
Collective Coupling- Provides collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.
When the stabilator (SCALP) provides collective coupling it…
Provides collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.
When the stabilator (SCALP) angle of incidence varies it…
Angle of Incidence- Decrease angle of incidence as airspeed increases to improve static stability
When the stabilator (SCALP) provides lateral sideslip to pitch it…
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.
When the stabilator (SCALP) provides pitch rate feedback it…
Provides pitch rate feedback to improve dynamic stability.
