When there is no reverse thrust command, an internal lock mechanism locks the actuators in the retracted position.
When there is a reverse thrust command, hydraulic pressure from the directional control valve (DCV) is directed to the extend and retract sides of the actuator piston. The extend pressure releases the actuator lock mechanism which unlocks the actuator piston. The piston extends because the surface area of the piston on the extend side is larger than the retract side of the piston. This permits the actuators to move the thrust reverser sleeve to the extended position in 2-3 seconds.
When the thrust reversers are commanded to retract, hydraulic pressure from the DCV is directed to the retract side of the piston. Hydraulic fluid in the deploy side tubing is directed to the hydraulic return line through the DCV. The actuators will retract and stow the thrust reverser sleeve in 3-5 seconds.
Training Information Point
The locking actuators are interchangeable but the correct plugs and unions must be installed in the actuator hydraulic ports for the installation at the center or lower position, left or right thrust reverser half.
Correct rigging of the thrust reverser actuators is done with the correct installation of the actuators. There are no adjustments that can be made after the actuators are installed. All adjustments to the actuators are made when the actuators are assembled at the fully retracted position per the component maintenance manual. Any adjustments to the actuators that are made during the installation, such as turning the actuator rod end changes the actuator length and can affect the operation of the thrust reverser actuation system. This can cause the T/R sleeve to bind or jam, operate slowly, cause damage to the actuator or damage to the thrust reverser structure.
The retract side of the thrust reverser hydraulic actuation system must be pressurized when a locking actuator is installed. The hydraulic pressure will make sure all the hydraulic actuators are completely retracted and the bullnose seal is compressed to correctly rig the thrust reverser actuation system. Do not remove the hydraulic pressure while you install the actuator.
EFFECTIVITY BEJ ALL 78-34-00
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D633W101-BEJ May 05/2003
PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
TRAS -LOCKING HYDRAULIC ACTUATORS
EFFECTIVITY BEJ ALL 78-34-00
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D633W101-BEJ May 05/2003
TRAS -NON-LOCKING HYDRAULIC ACTUATORS
General
The thrust reverser actuation system (TRAS) uses six hydraulic actuators to extend and retract the thrust reverser sleeves. There are two non-locking actuators for each engine.
The sync shafts make sure the actuators on each sleeve move together.
Purpose
The non-locking hydraulic actuators have these functions:
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