CAUTION: DO NOT CRANK THE LATCH ACTUATOR WITH MORE THAN
_______ 8 POUND-FEET TORQUE. THIS CAN CAUSE DAMAGE TO THE MANUAL DRIVE INPUT.
(a)
Manually crank the replaced latch actuator to move the latch pin to the fully retracted position (approximately 150 turns) and then back to fully extended position
(b)
If the operating torque is more than 20 pound-inches, adjust the latch fitting on the body frame (Ref 52-31-00/501).
S 864-022
(12) Make sure the door is in the fully closed, latched and locked position.
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747-400 MAINTENANCE MANUAL
S 214-023
(13)
Make sure that 2 green CLOSED lights and 16 green LATCHED lights on annunciator module come on.
S 214-024
(14)
Make sure EICAS message DOOR NOSE CARGO does not show.
F.
Put the Airplane Back To Its Usual Condition
S 864-025
(1) Remove electrical power, if it is not necessary (Ref 24-22-00/201).
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747-400 MAINTENANCE MANUAL
NOSE CARGO DOOR LATCH ACTUATOR - ADJUSTMENT/TEST
________________________________________________
1. General
_______
A. This procedure is used to find the defective actuator when you think there is a shorted diode in the actuator electrical system. The shorted diode condition is shown by the latch actuators (usually more than one) that drive hard against or through the open or closed internal stops. This condition can also be noted audibly by a change of sound as the actuator stalls against the stop.
NOTE: The actuator which drives against the internal stop is not the
____
one with the shorted diode.
B. You must do this test when there is a defective latch actuator with the damaged internal stops, unless you know the failure is caused by a damaged limit switch within the actuator.
C. The SYSTEM POWER and DOOR CONTROL switches are momentary switches. The two switches must be actuated simultaneously and held when you operate the nose cargo door. When one of the two switches is released, the door travel will stop. In this procedure, the door control switch refers to the use of the two switches.
TASK 52-31-05-725-001
2. Functional Test - Latch Actuator
________________________________
A. Standard Tools and Equipment
(1)
Voltmeter
B.
References
(1)
24-22-00/201, Manual Control
(2)
52-31-05/401, Latch Actuator
C.
Access
(1)
Location Zone
801 Nose Cargo Door
D.
Prepare For Test
(1)
Supply electrical power (Ref 24-22-00/201).
(2)
Make sure the nose cargo door is closed and latched.
(3)
Electrically open all the latches to the not fully-open position.
S 865-002
S 865-003
S 865-004
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S 865-005
(4)
Make sure these circuit breakers are closed:
(a)
On the Auxilary External 2 Power Center-Right panel P715: 1) NOSE CARGO DOOR
(b)
On the Power Distribution Center-Right panel P415: 1) 415F16, NOSE CARGO DOOR CONTROL
S 865-006
(5)
Open these circuit breakers and attach the DO-NOT-CLOSE tags:
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