R **ON A/C ALL
4. Power Supply
____________
Not Applicable
5. Interface
_________
Not Applicable
6. Component Description
_____________________
R (Ref. Fig. 007, 008)
A. Power Control Unit
(1) Description
The flap PCU is a hydro-mechanical unit. The main body, which is a case, contains a differential gearbox.
The Line Replaceable Units (LRUs) of the PCU are as follows:
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two hydraulic motors
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two Pressure-Off Brakes (POB)
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two valve blocks
-six solenoid valves
-two inlet filters
- one Feedback Position Pick-off Unit (FPPU)
- one Instrumentation Position Pick-off Unit (IPPU).
(a) Hydraulic Motor
R (Ref. Fig. 009)
Each multi-piston hydraulic motor receives hydraulic pressure from a valve block. The output shaft of the motor is connected to a POB. Hydraulic fluid lubricates the motor. The cylinders of the motor are connected to two ports, referred to as the extend and retract ports. When the valve block supplies hydraulic fluid to the extend port, the motor moves in the direction necessary to extend the flaps. When hydraulic pressure is supplied to the retract port, the motor moves in the opposite direction and the flaps retract.
R Power Control Unit Figure 007
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R Power Control Unit - Schematic Figure 008
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R Hydraulic Motor Figure 009
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(b) Pressure-Off Brake (POB)
R (Ref. Fig. 010)
A POB is attached to each hydraulic motor. It holds the output shaft of the hydraulic motor when:
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the hydraulic motors do not operate
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the related hydraulic system does not supply sufficient hydraulic power
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the WTB stops the flap transmission system because of some system failures.
The POB has a multiple friction-disk pack. Splines connect the stators to the POB casing and the rotors to the shaft in the center of the POB. Springs hold the friction disks together. When hydraulic pressure is applied to the POB, the friction disks are disengaged (against the pressure of the springs). To remove the POB, you must remove the related hydraulic motor first.
(c) Valve Block
R (Ref. Fig. 011)
The flap PCU has two valve blocks which are electrically controlled. Each valve block controls the flow of hydraulic fluid to its related hydraulic motor and POB.
The Linear Variable Differential Transducer (LVDT) is installed on one end of the valve block. The LVDT supplies a signal to the SFCC so that the SFCC can monitor the position of the control valve spool. Installed on the valve block opposite the LVDT are two directional solenoid valves and one POB solenoid valve. The directional solenoid valves operate as the extend or the retract solenoid valves. The POB solenoid valve operates as the brake solenoid valve.
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