Gulfstream G550 Operating Manual

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2A-29-10: General
1. Description:
The G550 aircraft has two hydraulic systems, left and right, each powered by an
engine driven pump installed on the respective left and right engine that
pressurizes fluid contained in dedicated reservoirs. The engine-driven pumps are
not equipped with off / on switches, but continuously operate unless the
respective engine is shut down with the cockpit fire handle. Both systems are
independent, each with separate lines and no common point for fluid interchange
to preserve the integrity of each system. However, since the failure of an engine-
driven pump or the engine itself would result in the loss of the autonomous
hydraulic system, replacement power sources are available. An overview of the
two hydraulic systems is shown in Figure 1.
Hydraulically powered aircraft components, except the engine thrust reversers,
are redundantly protected with either an alternate hydraulic power source, dual
(left and right) hydraulic actuators, hydraulic accumulator pressure or compressed
nitrogen (N
are powered using actuators connected to both hydraulic systems, with either
system capable of independently powering the controls. See the following table.
LEFT HYDRAULIC
SYSTEM POWER
*Because the rudder is essential to the control of the aircraft when operating with
only one engine, the rudder and yaw damper is also be powered by an Auxiliary
Control surfaces and aircraft sub-systems used in the takeoff and landing phases
of flight are subject to many cycles, higher force loads, and a require a greater
range of movement. For design simplicity they are powered by a single system,
the left hydraulic system. However, these components are protected with a high
level of redundancy. The left hydraulic system is unique in that left system fluid
may be pressurized by two sources other than the engine driven pump. An
electrically driven Auxiliary (AUX) pump, or an impeller driven by right hydraulic
system pressure, termed the Power Transfer Unit (PTU) can pressurize left
system hydraulic fluid. These two surrogate hydraulic pressurization sources offer
additional redundancy by using separate quantities of left system hydraulic fluid.
The PTU pressurizes normal left system fluid, but the AUX pump uses a
dedicated quantity of left system fluid preserved within the left system reservoir in
the event of left system fluid loss. If all left and AUX hydraulic fluid is lost, the
components essential to landing can be operated using pressure stored in
accumulators or nitrogen bottles. The following table illustrates the actuation
power sources for takeoff and landing controls, subsystems and actuators:
PRODUCTION AIRCRAFT SYSTEMS
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) bottle pressure. Control surfaces used throughout the flight regime
2
X
X
X
X
X
X
electric pump using left system fluid. See the following text and table.
TOC
OPERATING MANUAL
HYDRAULICS
FLIGHT CONTROL
SURFACE
Elevator
Aileron
Rudder / Yaw Damper *
Flight Spoilers
Speedbrakes
Stick Pusher
RIGHT HYDRAULIC
SYSTEM POWER
X
X
X
X
X
X
2A-29-00
Page 1
August 14/03