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AILERON AND FLAPERON CONTROL -WHEEL POSITION TRANSDUCERS

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AILERON AND FLAPERON CONTROL -WHEEL FORCE TRANSDUCER

Purpose

The wheel force transducer measures the total force from the captain and the first officer to the control wheels. The wheel force transducer sends analog electrical signals to the ACEs. The PFCs use these signals for the bank angle protection function.
Physical Description

The wheel force transducer is a spring with two electrically isolated LVDTs inside. The ACEs supply 7v ac, 1800 Hz excitation power.
The wheel force transducer is different from the two elevator force transducers.
The wheel force transducer attaches to the wheel left cable drum and to the left crank of the left shaft assembly.
Each LVDT has a separate cable which connects to the ACE connector bracket. This bracket has two receptacles, one for each LVDT of the force transducer. The order in which each LVDT connects to the connector bracket determines the interface of the LVDT with the ACE.
Location
The wheel force transducer is on the left shaft assembly, between the flight deck floor and the nose gear wheel well. Access is through the MEC, then along the left side of the nose gear wheel well.
Functional Description
When the pilot applies a force to the control wheel, the wheel force transducer spring extends or compresses. The LVDTs measure the spring movement.
The signal from one LVDT goes to the L2 ACE, and the other to the C ACE.
Indications
When both LVDTs of the wheel force transducer fail, the status message BANK ANGLE PROTECT shows.

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AILERON AND FLAPERON CONTROL -WHEEL FORCE TRANSDUCER

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AILERON AND FLAPERON CONTROL -AILERON PCU -LOCATION

Purpose

The aileron PCUs move the ailerons. Electrical command signals from the ACEs operate the aileron PCUs. Each aileron has two PCUs.
Location

The two PCUs are outboard on the wing rear spar. Access to the PCUs is by two hinged panels on the lower wing.
The kick link connects the PCU to the rear spar fittings. The actuator rod connects to the aileron at the aileron surface attach fitting. The reaction link connects to the aileron at the aileron attach fitting at the hinge line.
Two electrical connectors of different sizes connect to the upper side of the PCU.
Hydraulic tubing connects to ports, one on each side of the PCU. This tubing has fuses and check valves to help prevent the loss of hydraulic fluid if there is damage to the PCUs or hydraulic tubing. The fuses and check valves in the left hydraulic system are inboard of spoilers 1 and 14 in each wing. The fuses and check valves in the center hydraulic system are outboard of spoilers 1 and 14 in each wing.
Training Information Point
Removal and installation of the aileron PCU is in one assembly with the reaction link and the kick link.
To move the actuator for maintenance, depressurize the hydraulic systems. You get access to the manual bypass on the under side of the PCU. Turn the manual bypass to the bypass position while moving the aileron. After release of the manual bypass, it closes.
During installation of the aileron PCU, it is necessary to adjust the actuator null LVDT. Remove the LVDT access cover to adjust the LVDT.

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AILERON AND FLAPERON CONTROL -AILERON PCU -LOCATION

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777 AIRCRAFT MAINTENANCE MANUAL

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AILERON AND FLAPERON CONTROL -AILERON PCU -PHYSICAL DESCRIPTION

Physical Description

All four aileron PCUs are identical. Each aileron PCU, with its reaction link and kick link, weighs about 38 lb (17 kg).
The aileron PCU contains a hydraulic actuator with a control module. The control module contains:
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An electrohydraulic servo valve (EHSV)

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A bypass solenoid valve

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A blocking solenoid valve

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A mode selector valve

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An extension check and relief valve with manual bypass

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Two bypass check valves

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Two anti-cavitation check valves
　
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