Learjet 60 - Thrust Reverser System

Learjet 60

Pilot's
Manual
THRUST
REVERSER SYSTEM
Each engine is equipped with an independent, electrically controlled,
hydraulically actuated, target-type thrust reverser . The thrust rever-
ser system consists of a thrust reverser assembly installation on each
engine, thrust reverser levers on the main thrust levers, a throttle balk
solenoid, associated hydraulic plumbing and associated electrical wir-
ing . Each thrust reverser assembly installation consists of an upper
and lower target-type door, four-bar door linkage, an inboard and
outboard door actuator, two secondary latches, four stow switches
and one deploy switch . A hydraulic control unit (HCU) for each
thrust reverser is installed in the
tailcone . The HCU controls the hy-
draulic flow to the associated
thrust reverser in response to electrical
inputs . Hydraulic power
for thrust reverser operation is supplied by a
combination of engine driven hydraulic pump
flow and a thrust re-
verser accumulator . Pressure from the auxiliary
hydraulic
pump
is
not available to the thrust reverser system . The thrust
reverser accu-
mulator is plumbed primarily to power thrust reverser operations
but
assists the main system accumulator for landing
gear, flap and brake
operation . Refer to Section III for more
details on the thrust reverser
hydraulic system . Electrical
power for
thrust
reverser control and
auto stow functions is 28 VDC supplied
through the 5-amp L and R
TR CONT and the 5-amp L and R
TR AUTOSTOW circuit breakers
on
the pilot's and copilot's circuit breaker panels . The 7 .5-amp WARN
LTS circuit breakers supply electrical power for FADEC discrete
sig-
nals and a redundant power source for the annunciator circuits .
DEPLOY
In order to arm a thrust
reverser,
both squat
switches must be in the
ground mode (aircraft weight on wheels),
and the applicable thrust
lever must be in the IDLE detent .
When the prerequisite conditions are
met, a signal from the applicable thrust
reverser relay box will open the
applicable isolation valve (within the HCU)
allowing hydraulic pres-
sure to be available for thrust reverser deployment
. The presence of hy-
draulic pressure will actuate a pressure switch in turn
illuminating the
green TR ARM light . Lifting the thrust reverser
lever to the DEPLOY
detent will signal the applicable HCU
to apply hydraulic pressure to
the secondary latch actuators anddeploy port of the thrust reverser ac-
tuators
(inboard and outboard) . When the secondary latches are re-
leased, the secondary latch stow switches send a signal to illuminate
the amber
TR
UNLOCK
light . Once the thrust reverser doors move out
of
the stowed position, the primary latch stow switches send a discrete
signal to
the on-side FADEC to limit engine thrust to idle . When the
doors reach the fully deployed
position, the deploy switch sends a sig-
nal to extinguish the amber TR UNLOCK
light, illuminate the white
PM-123
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2-21
Change 3