AFCS Flashcards
19 functions
Pitch, roll, yaw stability augmentation Automatic Preflight Checks Hover augmentation/gust alleviation Cyclic, collective, and pedal trim Blade fold Pitch and roll attitude hold Airspeed hold Heading hold Turn Coordination Maneuvering Stability Radar altitude hold Barometric altitude hold Automatic approach to hover Hover coupler Automatic Depart Crew Hover Cable angle hover Fault diagnostics Stabilator control
Control mixing
Mechanical Collective to yaw Collective to lateral Collective to longitudinal Yaw to longitudinal
Electrical
Collective/airspeed to yaw
3 major components
Advanced flight control computer AFCC
Stability augmentation system SAS
Stabilator system
Four inputs to stab
Collective position
Lateral acceleration
Airspeed
Pitch Rate
Attitude hold
Airspeeds less than 50 KIAS
Using 4 way trim changes pitch rate at 5 deg/sec
Airspeed hold
Above 50 KIAS and AOB less than 30*
4 way trim changes at rate of 6 KIAS per second
4 way trim laterally changes roll at 6* per second
Heading hold
Yaw trim actuator, when weight off wheels
Below 50 KIAS depress pedals
Above 50 KIAS depress pedals and cyclic trim
Heading trim switch below 50 KIAS slewed at 3* per sec
Above 50 KIAS switch for less than 1 second will change heading 1, holding for greater than 1 second 1per sec turn
When is heading hold reengaged
When following for 2 seconds
Roll is within 2* of wings level
Yaw rate is less than 2* per second
Altitude hold
Computer stops collective at 106 and 120 for respective airspeeds
RADALT hold up to 5000 ft agl
Hover augmentation / gust alleviation
SAS 2 improves stability at low airspeeds by using attitude retention, longitudinal acceleration, and lateral acceleration to eliminate drift
Turn Coordination
Automatic above 50 KIAS
Heading hold disengaged when roll attitude is greater than 1* and any of the following
Lateral cyclic greater than 3 percent displacement
Cyclic trim rel button pressed
Roll attitude exceeds 2.5* using 4way trim
Maneuvering stability
Cyclic is moved forward to simulate loading at AOB greater than 30*
1% forward for every 1.5* AOB between 30 and 75*
Automatic approach to a hover
Above, 360ft/min airspeed hold
Below, 2.5 kt/s altitude hold
On 2.5 kt/s 215ft/min
Below 40kt on - 1.5 kt/s
130 ft/min
assumes wings level when engaged and again at 80 KIASHover coupler
can be varied +_10kts with 4 way
Engages when longitudinal velocity is within 1KGS of LONG pot, or within 5KGS if engaged manually
RADALT hold when within 2 feet of altitude selected
Stops pulling at 116% torque
Automatic Depart
To 120 KIAS and 150ft AGL
240ft/min climb
3 kt/sec below 85 KIAS
1 kt/sec above 100 KIAS
