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Friction Clamp Block
Elevator Stop
Figure 2: Trim Tab Actuator Assembly
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C. Trim Tab Actuator Assembly
The trim tab is a one-piece GFRP molding. The tab has 2 integral levers. Two cranked actuating levers attach to the integral levers. The left cranked actuating lever connects to the long flexible cable. The right actuating lever connects to a friction damper.
The friction damper has a clamp-block with a hole for a rod. The rod connects to the right actuating lever on the trim tab. You can adjust the friction of the rod in the clamp block.
3. Operation
When you move the top of the trim handwheel forward, these things happen: ) The small gear wheel moves the top of the gear segment forward. ) The gear segment pulls the inner core of the flexible cable forward. ) The inner core of the flexible cable pulls the left cranked actuating lever forward. ) The left cranked actuating lever pulls the trim tab lever forward to move the tab up. ) The up movement of the trim tab pushes the elevator down in flight giving nose-down trim.
When you move the top of the handwheel aft, the gear segment moves aft, the cable moves aft and
the trim tab moves down. This pushes the elevator up and gives nose-up trim.
In each case, the pilot can see the trim position from the white mark on the gear segment.
4. Emergency Operation
In the event of failure of the trim control system between the handwheel and the trim actuator lever, the friction damper will prevent trim tab flutter.
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Trouble-Shooting
1. General
The table below lists the defects you could have in the elevator trim control system. If you have the trouble detailed in the Trouble column read across to the Possible Cause column. Then do the repair in the Repair column.
Trouble Possible Cause Repair
Too much play in the trim system. Worn bearings or joints. Replace the defective items.
Trim handwheel stiff to move. Flexible cable damaged. Trim damper incorrectly adjusted. Replace the flexible cable. Adjust the trim damper.
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Maintenance Practices
1. General
These maintenance practices tell you how to test the elevator trim control system. They also tell you how to adjust the system. Refer to Section 55-20 for data on how to remove and install the elevator and trim tab.
2. Elevator Trim Control System Test for Correct Range of Movement
A. Equipment
Item Quantity Part Number
Control clamp. 1 Commercial.
Inclinometer. 1 Commercial.
Fuselage trestle. 1 Commercial.
B. Elevator Trim Control Test Procedure
Note: Make sure that the airplane does not move in pitch during the procedure. It will cause errors in the test.
Detail Steps/Work Items Key Items/References
(1) Make a copy of the Control Surfaces Adjustment Report. Refer to Section 06-00. Use it to record the measurements.
(2) Put a trestle under the rear fuselage. To prevent movement in pitch.
(3) Hold the trailing edge of the elevator in line with the horizontal stabilizer Use a clamp at the tips.
(4) Set the trim handwheel to neutral.
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