Gulfstream G550, Operating Manual

Page: 36 / 94

2A-27-40: Aileron Roll Control
1. General Description:
The flight crew controls the motion of the aircraft around the longitudinal axis by
displacement of the ailerons. The ailerons, composed of baked epoxy graphite
fabric, are mechanically linked to the pilot and copilot control yokes by a dual
installation of multi-strand braided cables and a system of pulleys and bellcranks.
A hydraulic actuator is incorporated in the cable linkage of each aileron to provide
a powered assist in deflecting the ailerons. The hydraulic actuators provide a
boost advantage of six to one (6 : 1) to pilot manual yoke inputs. Rotation of the
control yokes left or right produce a roll in the corresponding direction. Each
control yoke is linked to one aileron: the pilot yoke is cable-linked to the left aileron
and the copilot yoke is cable-linked to the right aileron. Although the ailerons are
independently linked, the control yokes are coupled together by a mechanical arm
beneath the cockpit floor so that rotation of one yoke will rotate the other yoke,
producing motion in both ailerons. Like the elevator system previously described,
the link between the control yokes may be separated if a malfunction causes one
aileron to become inoperative. A disconnect handle on the copilot side of the
center pedestal can be pulled out to separate the link between the yokes, allowing
independent operation of the free (unjammed) aileron.
Operation of the ailerons is symmetrical but opposite. If a control yoke is rotated to
the left to command a left roll, the aileron on the trailing edge of the right wing
deflects downward, producing a small change in the chord of a section of the
wing, and creating lift. The right wing then rises due to the increased lift
component. At the same time the aileron on the left wing trailing edge deflects
upward, disrupting airflow over the wing and decreasing lift. The left wing falls due
to the decrease in lift on a portion of the wing. A roll in the opposite direction is
accomplished by reversing the direction of the aileron deflection, creating the
same circumstances on opposite wings. The maximum aileron deflection is
eleven degrees (11°) up or down.
To increase the response time for roll commands, two of the three spoiler panels
on each wing are mechanically coupled to the aileron control cable linkage. The
two outboard spoilers on the falling wing (with the aileron deflected up) deploy,
creating additional disruption of airflow over the wing to increase roll rates. The
spoiler panels on the upward moving wing (with aileron deflected downward) do
not move, remaining faired with the upper wing surface.
A single trim tab on the left aileron is manually positioned to reduce control yoke
forces in maintaining a stabilized condition around the longitudinal axis. An aileron
trim wheel on the aft section of the cockpit center pedestal is linked by a cable
directly to the trim tab. The trim wheel is rotated left and right to produce the
corresponding trim input to position the left aileron. Since the ailerons are linked
through the mechanical connection between the control yokes, moving the left
aileron will move the right aileron in the opposite direction for a equal amount of
deflection. The trim tab has a ceramic surface surrounding the hinge points that is
heated to prevent ice formation that might interfere with tab operation.
The autopilot is integrated into the cable linkage to the ailerons through electric
servos. The aileron cables are wrapped around a drum driven by the servos. The
autopilot servos rotate the drum, producing cable inputs to position the ailerons.
NOTE:
The autopilot has no trim input to the ailerons
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS
2A-27-00
Page 36
August 14/03
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