AFCS / STAB SYS Flashcards
The AFCS is what type of system?
electrohydromechanical
Define inner-loop.
Inner-loop is our SAS capability which employs rate dampening to improve stability.
It has fast response and limited authority.
Operates without movement of the flight controls.
Define outer-loop.
Outer-loop (auto-pilot) provides long term inputs by trimming the flight controls with 100% authority to move the flight controls through their full range of motion, at a limited rate of 10% per second.
What is the CILA? What is it commanded by?
the collective inner-loop actuator (CILA) is commanded by SAS 2.
the collective SAS operates with RADALT, BARALT, APPR/HVR, and DEPART modes engaged and is limited to +/- 10% control authority.
What is the difference between SAS 1 and SAS 2?
SAS 1 is an analog system. SAS 2 is a digital system.
Their functions are identical except that SAS 2 also provides: hover augmentation/gust alleviation, altitude hold/coupler features, turn coordination, and roll attitude hold.
SAS 1 is not linked to the AFCC.
With both SAS channels engaged, the pitch, roll, and yaw actuators have ______ control authority with each channel providing ______.
+/- 10%, +/-5%
When does the [SAS] caution appear?
if SAS 1 and SAS 2 lose electrical power or when hydraulic pressure is lost to the actuators
What happens when one SAS channel fails?
if either channel malfunctions, the [AFCS DEGRADED] caution appears.
if SAS 2 fails, the AFCC will auto-disengage the affected axis. if SAS 1 fails, the pilot must manually disengage SAS 1.
the remaining operable SAS channel is limited to +/-5% control authority, but operates at 2x it’s normal gain to partially compensate for the failed channel.
List the 19 functions of the AFCS.
5 Holds: Attitude Hold Airspeed Hold Heading Hold RADALT BARALT
5 Hovers: Automatic Approach Automatic Departure Hover Coupler Crew Hover Cable Angle Hover
3 "-ations": Stability augmentation Hover augmentation / gust alleviation Turn coordination
MTDABS: Maneuvering stability Trim Diagnostics (fail advisory) Automatic preflight checks Blade fold Stabilator control
Attitude Hold
engaged with the autopilot pushbutton.
attitude hold is used < 50 KIAS and commanded through cyclic trim release or 4-way trim.
auto-leveling transitions helo from left wing down in a hover to wings level at 50 KIAS.
Airspeed Hold
engaged with the autopilot pushbutton above 50 KIAS and AOB < 30 degrees.
Heading Hold
engaged with autopilot and WoffW.
trim switch on collective will slew HDG at 3 deg/sec. when < 50 KIAS.
> 50 KIAS: 1 sec. click = 1 deg. HDG change or 1 deg/sec coordinated turn
Altitude Hold (BARALT / RADALT)
engaged with SAS 2, trim, and autopilot engaged.
AFCC monitors torque and will stop collective increase if <80 KIAS torque rises to 120% or >80 KIAS torque rises to 106%.
BARALT: AFCC uses the air data transducer as the reference altitude
RADALT: AFCC uses radalt info as reference, can be engaged at any altitude 0-5000’ AGL
Automatic Approach
can be initiated at any airspeed and altitude < 5000’ AGL
On profile >40kts: 215fpm descent / 2.5kt/sec decel.
On profile <40kts: 130fpm descent / 1.5kt/sec decel.
Above profile: 360 fpm descent / airspeed hold
Below profile: RADALT hold / 2.5kt/sec. decel.
Automatic Departure
can be performed from a coupled hover or automatic approaching will terminate at 150’ / 120kts
Profile:
< 85kts: 3kt/sec accel. / 240fpm climb
>100kts: 1kt/sec accel. / 240fpm climb
AFCC monitors torque to prevent increase >120% below 80kts and above 106% above 80kt.
