Figure 3: Flap Actuator Installation
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Flight Controls
AMM
3. Operation
If you operate the flap selector switch these things happen: ) The switch energizes the related logic circuit. ) The logic circuit switches on the related transistors to supply power/ground to the flap motor. ) The flap motor turns the reduction gear and spindle. This moves the push-rod towards the new set position. ) The push-rod turns the idler lever around its axis. ) The idler lever moves the push-rods in the fuselage and the wings. ) The push-rods move the bellcranks in the left and right wing. ) The two short push-rods move the flaps. When the flaps come to the set position: ) The cam on the flap actuator operates the related position and indication micro-switches. ) The logic circuit switches off the related transistors to de-energize the motor. ) The flap position indicator shows the new flap position.
4. Fail-Safe Operation
The flap control system has these safety properties:
) If the LDG position micro-switch fails closed the flap actuator push-rod will continue to travel for about 5 mm (0.2 in.) until it reaches an internal stop. This prevents damage to the flaps. The FLAP circuit-breaker opens.
) If the UP position micro-switch fails closed, the actuator push-rod contacts the end of the actuator body after about 5 mm (0.2 in.) of movement. This prevents damage to the flaps. The FLAP circuit-breaker opens.
) If there is a mechanical failure in the controls to one flap, the torsion tube prevents asymmetric flap movement.
Doc # 6.02.01 Page 7
Rev. 4 09 Jan 2003
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AMM
Flap Selector Switch Flap Position Indicator
UP LED
T/O LED
LDG LED
FLAP CONTROL UNIT IN THE INSTRUMENT PANEL (View Looking Forward)
Closed Closed
T/O Indication
Micro-Switch
T/O Position Moving Up Micro-Switch
MICRO-SWITCH BOARD (View Looking Down)
Figure 4: Flap Electrical Control System
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Flight Controls
AMM
Trouble-Shooting
1. General
The table below lists the defects you could have in the flap 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
Flaps do not operate. Circuit breaker not set. Airplane electrical system voltage low. Flap selector switch defective. Set the flap circuit breaker. Do a test of the airplane electrical system voltage. Replace the flap electronic control unit.
Flap circuit-breaker will Short to ground in the wires to the Do an insulation test between
not stay closed. electrical control unit or the micro-switches. Short to ground in the electrical control unit. Short to ground in a micro-switch. Short to ground in a wire between a closed micro-switch and the control unit. each wire and ground. Repair or replace defective wires. Replace the electrical control unit. Replace the micro-switch. Do an insulation test between each wire and ground. Repair or replace defective wires.
Flap circuit-breaker opens when flap selector switch moved to any down position. Short to ground in a motor supply wire. Do an insulation test between each wire and ground. Repair or replace defective wires.
Flap circuit-breaker opens when flap selector switch moved to any up position. Short to ground in a motor supply wire. Do an insulation test between each wire and ground. Repair or replace defective wires.
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