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MAINTENANCE MANUAL

Wing Gear Uplock Actuator
Figure 5

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MAINTENANCE MANUAL

UNLOCK  BLEEDER 
PRESSURE 
RESTRICTOR PLUG 
HEAD END 
ROD END 
HOUSING 
PISTON 
CYLINDER BARREL 
LOCK PRESSURE 
PACKING 
RING  O-RING 
BLEED PLUG 
(TWO LOCATIONS
RINGS  ON ROD END 
OF ACTUATOR) 
RETAINER 
VALVE 
Wing Gear Downlock Actuator 
Figure 6 

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MAINTENANCE MANUAL

 11. Operation
_________
 A. Functional Description
 (1)  
The wing landing gear operating sequence is shown in figure 7. Hydraulic schematics of the wing landing gear system in various conditions are shown in figure 8.

 (2)  
When gear is up and gear doors are closed, the door-operated sequence valve blocks fluid from unlocking the uplock and from lowering gear. When gear is selected DN and doors are opening, the sequence valve is positioned so fluid is directed to the unlock side of uplock actuator which unlocks wing gear. As doors continue to open, the sequence valve is positioned so fluid is directed to the down side of the gear actuator and gear extends.

 (3)  
After the gear is down and locked, the doors close. This repositions the sequence valve to shut off fluid to the door actuator and the uplock actuator. When UP is selected, fluid is blocked by the sequence valve until the doors begin to open. When the doors are fully open, fluid is directed to the unlock side of the downlock actuator and to the up side of the gear actuator. When the gear is up and locked, the doors again close, repositioning the sequence valve so that fluid is blocked from the actuators.

 (4)  
When the gear is up and locked and DN is selected hydraulic fluid is directed to the down ports of the downlock and uplock operated sequence valves. Since the gear is up and locked and the doors are closed, the uplock operated sequence valve is in the hook closed position. This allows fluid to be directed through the valve to the open side of the door actuator thus opening the doors.

 (5)  
When the gear unlocks and extends, the uplock operated sequence valve is mechanically positioned to shutoff fluid flow to the open side of the door actuator. This positioning of the valve also allows fluid to be directed through the interconnect line from the downlock operated sequence valve, through the uplock operated sequence valve to the CLOSE port of the door actuator, thus closing the doors. When gear UP is selected, fluid is directed to the sequence valve UP port. The sequence valve is in the downlock engaged position which directs fluid to the open side of the door actuator, thus opening the doors.

 (6)  
When the gear is down and locked, the flow thru the interconnect line from the downlock operated sequence valve is restricted to slow the door closing speed.

 (7)  
When the downlock actuator unlocks, the sequence valve moves to the downlock disengaged position; however, fluid is still directed through the uplock operated sequence valve to the open side of the door actuator as the gear is retracting. When the gear is up and locked, the uplock-operated sequence valve is repositioned to direct fluid to the closed side of the door actuator.

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