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MAINTENANCE MANUAL

 (2)  
The rotary switch energizes the electric motor clutches and commands a closed loop electrical system that selects the same seven flap positions as the hydraulic control system (except that slats are fully extended for the 20-unit position selection) . Slats are commanded to the fully extended position for the 20-, 25-, and 30-unit positions, and to the intermediate position for the 1-, 5-, and 15-unit positions. Flaps extend to the same positions as under normal hydraulic control.

 C.
Flap Control Cables

 (1)  
Two control cables, WFA and WFB, are attached to the cable drum on the flap control lever. Control movements of the flap control lever are transferred to the flap drive system by these cables. Cable WFA is the flap retract cable and cable WFB is the flap extend cable.

 (2)  
The control cables run from the cable drum under the cabin floor and back to the PDU at the forward end of the left main wheel well.

 (3)  
The control cables are attached to the flap PDU input drum.

 D.
Flap Power Drive Unit (PDU) (Fig. 9)

 (1)  
The flap power drive unit is the source of mechanical power for the flap drive system.

30-UNIT DETENT (FLAPS AND SLATS FULLY EXTENDED)
WFB CABLE
CABLE DRUM
POSITION TRANSMITTER LEVER
Figure 8

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MAINTENANCE MANUAL

TE FLAP PDULOCATION
WFA CABLE  CONTROL VALVE 
(PRIMARY DRIVE) HYDRAULIC MOTOR  BYPASS VALVE 
TORQUE TUBE  TORQUE TUBE 
DRIVE) (ALTERNATE MOTOR ELECTRIC WFB CABLE  POSTION TRANSMITTER 
HOUSING GEARBOX 

Flap Power Drive Unit (PDU)
Figure 9

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MAINTENANCE MANUAL

 (2)  
The flap PDU is a gearbox housing. Mounted on the housing is a hydraulic motor, alternate electric motor, hydraulic bypass valve, control valve assembly, mechanical controls and a rotary position transmitter.

 (3)  
The hydraulic and electric motors drive the common gear train which drives the torque tubes.

 (4)  
The hydraulic motor powers the flap drive system during normal operation. The motor is a constant displacement, bent axis, piston type motor, designed for reversible operation at a supply system pressure of 3000 psi. The hydraulic motor has a rated speed of 3760 RPM which drives the PDU gear train to yield a torque tube output of 857 RPM.

 (5)  
The alternate electric motor is mounted on the PDU housing and provides power to the flaps if hydraulic power is not available. The electric motor is a 400-Hz, 3-phase, 115 VAC motor with a cable clutch and a planetary gear set final drive.

 (a)  
The motor is controlled by FSEU-3 and relays for extension or retraction. The rotary position selector switch commands motor actuation through the FSEU.

 (b)  
A solenoid engages the cable clutch when AC power is supplied to the motor.

 (c)  
A torque limiter in the motor housing protects the motor in the event of a drive system jam.

 (d)  
The alternate electric motor has a rated speed of 275 RPM which gives a PDU output speed of 164 RPM.

 (e)  
Maximum duty cycle for the electric motor is 4 minutes (3 minutes off) to avoid overheating.

 (6)  
The hydraulic control valve directs hydraulic fluid to the retract or extend ports of the hydraulic motor to power the flap drive system.

 (a)  
The control valve is a mechanically operated slide valve containing a solenoid valve to override normal slide position.

 (b)  
Position of the valve slide is determined by rotation of an input crank. The input crank is driven by a linkage system which positions the crank according to location of cams in the PDU.
　
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