Automatic depart
Crew hover
Longitudinal stick gradient augmentation
(pitch bias actuator)
Blade-fold assist
Automatic preflight check
Diagnostics (mode failure display)
Figure 8-31.-Stabilator control panel.
AFCS Control Panels
The pilot controls the AFCS from the AFCS
DEGRADED light on the caution/advisory panel. They
CONTROL panel and the stabilator control panel
will also illuminate the appropriate mode failure
(figs. 8-30 and 8-31). The stabilator control panel
capsule on the failure advisory section of the AFCS
contains all the operating controls for the stabilator.
CONTROL panel. Stabilator failures illuminate the
All the other AFCS controls are on the AFCS
STABILATOR caution light on the caution/advisory
CONTROL panel. All detectable AFCS mode failures,
panel and generate an aural warning tone in the
except the stabilator, illuminate the AFCS
pilot's and ATO's headsets.
The AFCS CONTROL panel has switches to
electronically engage the SAS 1, SAS 2, and a
SAWBOOST HYD switch. The SAS/BOOST HYD
switch controls pressure application to SAS actuators
and pitch boost servos.
Stability Augmentation System (SAS)
The SAS 1 system provides electrical control
signals proportional to sensor inputs to the pitch, roll,
and yaw servo valves. The servo valves convert
electrical control signals into hydraulic commands for
the SAS actuators. The SAS actuators respond to the
hydraulic commands and produce mechanical
movement of the flight control linkages without
moving the cyclic sticks and pedals. The flight control
linkages direct changes in main rotor and tail rotor
pitch.
With both SAS 1 and SAS 2 engaged, the SAS
actuators each have 10 percent authority of flight
control movement. Each SAS system has 5 percent
authority. With only SAS 1 engaged, the gain of the
SAS amplifier is double, but the control authority
remains at 5 percent. The AFCS control panel
provides a signal to the SAS amplifier to indicate SAS
2 engagement.
The SAS 1 pitch channel provides dynamic
stability for the helicopter's pitch axis. The No. 1 pitch
rate gyro senses changes in pitch rate and applies this
rate to the No. 1 stabilator amplifier. The No, 1
Figure 8-30.-Helicopter automatic flight control
stabilator amplifier filters this pitch rate signal and
system panel.
applies it to the SAS amplifier. The SAS amplifier
processes
the
pitch
rate
signal
to
