If an attempt is made to force the aileron trim control wheel past its
mechanical stops, a shear pin breaks to disconnect the control wheel from
the torque tube, disabling roll trim.
G. Failure Detection System:
CAA Certified Aircraft Only: A flight control automatic failure detection
system monitors force applied to the aileron input / manual reversion rod,
providing detection of a jammed or malfunctioning aileron actuator. If the
system detects a failure, it automatically shuts off all hydraulic pressure to
that actuator (the opposite actuator remains unaffected) and triggers the
appropriate warning on the Crew Alerting System (CAS).
With the roll flight control system operating normally, forces on the aileron
input / manual reversion rod remain relatively low because there is no lag
between control wheel input and actuator output. If an actuator
malfunctions resulting in an aileron hardover action, force levels on the rod
increase significantly. When this force exceeds 150 pounds, a force-link
limit switch closes to energize an associated time delay relay.
Similarly, a jammed actuator results in increased control inputs being
applied by the flight crew. If these control inputs exceed approximately 20
pounds, the force-link limit switch closes to energize an associated time
delay relay.
If the time delay relay remains energized for more than ½ second, it
energizes a shutoff relay. The shutoff relay, in turn, powers the actuator’s
Combined and Flight hydraulic system shutoff valves to the closed position.
Closing of the shutoff valves also causes an amber L-R AIL HYD OFF
message to be displayed on CAS.
3. Controls and Indications:
(See Figure 14.)
A. Circuit Breakers (CBs):
Circuit Breaker Name: CB Panel: Location: Power Source:
L AIL HYD S/O (1) CPO A-14 Essential DC Bus
R AIL HYD S/O (1) CPO B-14 Essential DC Bus
NOTE(S):
(1) CAA certified aircraft only.
B. Caution (Amber) Messages and Annunciations:
CAS Message: Cause or Meaning:
L AIL HYD OFF (1) The flight control automatic failure detection system has
shut off Combined and Flight hydraulic system pressure to
the left aileron actuator.
R AIL HYD OFF (1) The flight control automatic failure detection system has
shut off Combined and Flight hydraulic system pressure to
the right aileron actuator.
RETRIM L-R WING
DOWN
Lateral axis out of trim.
NOTE(S):
(1) CAA certified aircraft only.
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS 2A-27-00
Page 45
January 31/02
Revision 6
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