5J-8 Developed for Training Purposes Citation Bravo
March 2009
CAE SimuFlite
The control valve of the thrust
reverser system routes high pressure
to one of two lines, depending on
whether the deploy or stow sequence
is activated. The low pressure or
return line is always the opposite
line. From the control valve, the
return line bypasses the isolation
valve and returns to the aircraft
hydraulic system through a check
valve that prevents surge pressures
from blocking the return line.
Actuators
Each thrust reverser has two actua-
tors, one on each side of an alumi-
num support beam on the inboard
and outboard sides of the engine
exhaust. The actuators transform
hydraulic energy into mechanical
power to open and close the thrust
reverser doors through a linkage sys-
tem on a sliding track. An overcenter
feature in the linkage locks the
reverser in the stowed position.
Two hydraulic lines connect to ports
used for high pressure and return
lines, depending on the mode of
operation selected in the cockpit.
The control valve in the aft tailcone
provides inputs to the actuators
through two flex hoses.
Mechanically actuated limit
switches connect to the actuators to
provide cockpit indications. When
the actuators move, the stow limit
microswitch closes and the
UNLOCK annunciator
(Figure 5J-
3)
illuminates. Once the doors are
fully open, the deploy limit micro-
switch closes and the DEPLOY
annunciator illuminates.
Normal operating pressure for the
actuators is 1,500 PSI with a fluid
temperature range of -65 to 225°F.
When this high pressure is applied to
the actuator, an extend force of
9201bs is available; the stroke is
5.215 ±0.015 inches.
Isolation Valve
The isolation valve, which is
upstream from the hydraulic bypass
valve, isolates the control valve and
the actuators from the aircraft
hydraulic system while thrust revers-
ers are not in operation by blocking
off the high pressure inlet port. With
the thrust reverser levers selected to
DEPLOY, 28 VDC flows to the iso-
lation valve solenoid; this opens the
valve to direct hydraulic pressure to
the control valve. The solenoid
remains energized while the system
is in the deploy mode.
With the thrust reverser levers in
STOW, the stow switches close to
energize the isolation valve during
the stow cycle. Upon completion of
the stow cycle, the stow switches
open to remove power from the iso-
lation valve solenoid. The isolation
valve then closes to isolate the con-
trol valve system from hydraulic
supply pressure.
An electrical signal from the thrust
reverser levers actuates both the iso-
lation and control valve.
The isolation valve is wired through
the LH/RH ENGINE FIRE PUSH
switchlights. If either switchlight is
pressed, electrical power is removed
from the isolation valve, which then
closes to prevent thrust reverser
deployment on the affected engine.
Control Valve
The control valve, which is down-
stream from the isolation valve, has
two independently energized sole-
noids: one for the deploy cycle, the
other for the stow cycle. The sole-
noids move the control valve. The
control valve directs hydraulic pres-
sure to the actuator deploy or stow
Thrust Reverser Limitations
Reverse thrust power must be
reduced to the idle reverse detente
position at 60 K1AS on landing
roll.
Maximum allowable thrust reverser
deployed time is 15 minutes in any
one hour period (on the ground for
maintenance).
Thrust reversing on sod/dirt or
gravel runways is not allowed.
Use of thrust reversers is prohibit-
ed during touch and go landings.
Maximum crosswind component
for use of thrust component for use
of thrust reverser is 25 kts.
Maximum reverse thrust setting is
limited to no more than maximum
takeoff power less 2% N
1
for the
existing ambient temperature.
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