Gulfstream G550, Operating Manual

Page: 38 / 94

to retract the pin, a trigger mechanism beneath the handle can be activated
to supply additional gas cartridge pressure to assist in retracting the pin. If
the cartridge assist is used, the aileron channel linkage cannot be
reconnected in flight since it requires special maintenance tools. However,
if only manual force is used to disconnect the aileron channels, the pin may
be reinserted in the mechanical arm link by pushing in on the handle if it is
determined that the malfunctioning aileron has returned to normal
operation.
C. Aileron Hard Over Prevention System (HOPS):
The conformity of the motion of aileron hydraulic actuators to aileron
control inputs from cockpit yokes or the autopilot is monitored by force link
mechanisms. The force links are the sensing elements that initiate aileron
HOPS activation. (See the flight controls HOPS system diagram in Figure
3). The mechanisms are essentially telescoping tubes with two sections -
one section that travels within the other. The end of one section of the tube
is connected to the cable linkage control inputs to the hydraulic actuator
and the end of the other tube section of the is connected to the actuator
shaft output to the aileron. The dual tube mechanism thus parallels the
action of the aileron actuator. Each tube section is spring loaded to resist
the push and pull motion transmitted through the actuator to move the
aileron. If a control cable input to the actuator is in the push direction and
the actuator shaft does not transmit a push assist or the aileron does not
move, the spring at the push end of the force link tube is compressed, and
an electrical contact within the spring initiates a signal to the hydraulic
control valves of both left and right aileron hydraulic actuators to bypass
system pressure. (If a resistance to control link input is present in the pull
direction, the spring and electrical contact at the end of the other section
would operate in the same way to activate HOPS bypass of hydraulic
pressure.)
The electrical signal incorporates a one half (½) second delay before
activating the hydraulic pressure bypass. Once activated, the control
valves are latched to the bypass position. If, in the judgement of the flight
crew, the condition causing the malfunction is transient, and the use of the
ailerons is deemed essential to continued safe flight and landing, the
HOPS initiated bypass can be reset by cycling both the LEFT AIL HYD S/O
and RIGHT AIL HYD S/O circuit breakers. If the malfunction is still present
the control valves will re-latch to the bypass state after the one half (½)
second delay. The left aileron shut off valve is powered by the left essential
DC bus and the right aileron shut off valve by the right essential DC bus.
When the electrical signal bypasses hydraulic pressure to the actuators,
signals are also sent to Input / Output (I/O) modules in the Modular
Avionics Units (MAUs). The left aileron state is communicated to MAU #1
and the right aileron state to MAU #2. The MAUs communicate with the
Monitor and Warning System (MWS) that formats the appropriate
messages for presentation on the Crew Alerting System (CAS) window.
To prevent inadvertent HOPS bypass of the aileron actuators during flight
conditions requiring quick reversals of the ailerons, the actuation of the
HOPS is filtered by:
•
The compression of the springs within the force link sections
•
Inertia in hydraulic piston action
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS
2A-27-00
Page 38
August 14/03
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