THRUST REVERSER SYSTEM - DESCRIPTION AND OPERATION
1. General
A. A thrust reverser system for each engine is used by the pilot to reduce the length of the landing
roll. The thrust reverser system consists of the following subsystems: thrust reverser assembly,
thrust reverser control system, and thrust reverser position indicating system. The thrust
reverser assembly, installed on the aft end of the engine, reverses the direction of engine
exhaust gas flow during reverse thrust operation. The thrust reverser control system consists of
controls installed at the engine drum-and-shaft assembly on the wing front spar above the
engine, hydraulic plumbing, and a push-pull cable running between the controls and the thrust
reverser. The control system, operated by a control lever on the throttle controls in the control
cab, directs system A hydraulic pressure to the thrust reverser for the selected mode (forward
or reverse) of thrust reverser operation. The thrust reverser position indicating system consists
of indicator lights in the control cabin, solid state switches mounted in a switching module, and
switch sensors installed on the thrust reversers.
B. See 78-32-101 for description of the thrust reverser assembly, 78-34-01 for description of the
thrust reverser control system, and 78-36-01 for description of the thrust reverser position
indicating system.
THRUST REVERSER - MAINTENANCE PRACTICES
1. General
A. This procedure provides a method of manually locking the thrust reverser in the forward thrust
position. This procedure is to be used for dispatch of an airplane with an inoperable thrust
reverser.
2. Equipment and Materials
A. Thrust Reverser Isolation Valve Ground Lock Cap and Pin Assembly - F80109-3 or
F80109-9 (preferred)
B. 3-foot lever (crowbar, prybar, steel tube etc.)
C. Protective tape
3. Manually Deactivate Thrust Reverser
A. Deactivate the affected thrust reverser hydraulic system by installing a ground lock cap and pin
in the applicable thrust reverser isolation valve.
WARNING: SERIOUS INJURY CAN RESULT TO PERSONNEL IF GROUND LOCK CAP
AND PIN IS NOT PROPERLY INSTALLED. ATTEMPT TO STOW THRUST
REVERSER AFTER INSTALLING GROUND LOCK CAP AND PIN. REVERSER
SHOULD NOT STOW.
B. Pull and tag the affected THRUST REVERSER circuit breaker on panel P6.
C. Remove screws attaching actuator housing fairings to thrust reverser and remove both fairings
(if necessary) (Fig. 201).
D. If malfunction requiring deactivation is attributed to hydraulic system, proceed as follows:
(1) Apply protective tape to end of lever.
NOTE: Protective tape is used to prevent damage to thrust reverser guide carriage and
shroud assembly box.
(2) Manually move deflector doors as close to the stowed position as possible.
(3) Position tip of lever under either lug of guide carriage and using the shroud assembly box
as a fulcrum, pry guide carriage aft until an over center position is reached.
CAUTION: WHEN PRYING GUIDE CARRIAGE AFT, USE CARE TO PREVENT
SCRATCHING ACTUATOR HARDWARE.
E. Repeat step D on opposite side.
F. Attach actuator-housing fairings (if removed) to thrust reverser with screws.
NOTE: Due to deflector door preload it is necessary to pry edges of doors open to slide
actuator-housing fairings into place.
G. If malfunction requiring deactivation is attributed to a jammed deflector door actuator, proceed
as follows:
(1) Manually move deflector doors as close to the stowed position as possible.
(2) Remove bolt, washers and nut securing actuator rod to guide carriage.
(3) Firmly secure actuator to shroud assembly box with lockwire or suitable equivalent.
(4) Pry guide carriage over center per steps D. (1) and (3).
H. Repeat step G. on opposite side.
I. For all malfunctions, deactivate the thrust reverser.
(1) Make sure the thrust reverser is locked in the forward position.
(a) Look at the links from the aft inboard side of each actuator fairing.
(b) The over center links and guide carriage must be in the locked over center position
(Fig. 202).
(2) Lockwire the reverse thrust lever to the forward thrust lever.
(3) Install a ground lock Cap and Pin on the applicable isolation valve in the air conditioning
equipment bay (Fig. 203).
(4) Open the thrust reverser circuit breaker and attach a DO NOT CLOSE tag.
(5) Put a REVERSER INOP tag on the reverse thrust lever.
(6) Put a REVERSER INOP tag on the REVERSER UNLOCKED light.
J. Reinstall actuator housing fairings (if removed) per step F.
THRUST REVERSER SYSTEM - ADJUSTMENT/TEST
1. Thrust Reverser System Adjustment
A. General
(1) The only adjustments (rigging) normally required when installing a thrust reverser, is a
check of the thrust reverser push-pull control cable rigging, and a check of the deflector
door fairing step and gap limits. Components of the thrust reverser assembly requiring
rigging (deflector doors and linkage) are normally rigged during buildup of the thrust
reverser assembly prior to installation of the assembly on the airplane. If rigging of any of
these components is required, perform rigging according to instructions in the respective
component maintenance practices.
(2) Rigging of the thrust reverser controls other than the follow-up controls is accomplished by
rigging the engine controls. For rigging of the follow-up controls and the thrust reverser
push-pull cable, refer to 78-34-32.
(3) Adjustment of the reverse thrust detent is required under the following conditions; after
replacing an engine fuel control unit, after changing an engine and after adjustment of any
engine control system.
2. Thrust Reverser System Test
A. General
(1) A functional test of the thrust reverser and controls operation is performed using the
system B electric motor-driven pumps to provide the actuating force. Thrust reverser
actuation is also checked using the thrust reverser alternate hydraulic pressure source.
(2) The thrust reverser system test consists of a system indication test, a circuit check, and a
thrust reverser operational test. The landing gear air-ground sensing system, fire switch,
and pressure line check valve operation are also tested.
WARNING: BEFORE OPERATING THRUST REVERSERS, ENSURE THAT
ADEQUATE STEPS ARE TAKEN TO PREVENT INJURY TO PERSONNEL
OR DAMAGE TO EQUIPMENT.
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