(a)
If a group of flaps does not move within a certain amount of time after the flap control lever is moved, the FCU sets a disagree. The FCU then switches that flap group to primary electric mode and activates the flap drive electric motors.
(b)
In primary electric mode, the flaps respond to the flap control lever in the same sequence as they do for primary hydraulic/pneumatic mode. Flap movement is much slower under electric power than under hydraulic and pneumatic power. A LE flap group (group A or B) in primary electric mode will return to primary pneumatic mode as soon as the flap group reaches the commanded position.
(c)
If the FCU sets a disagree while a flap group is in primary electric mode, the FCU will continue to energize the electric motors, even though there may be no flap movement.
(d)
The times delays for the FCU to set a disagree are:
1) TE Hydraulic - Extend: 7 sec
-
Retract: 7 sec
2) TE Electric - Extend: 25 sec
-
Retract: 25 sec 3) LE Pneumatic - Extend: 35 sec in air, 15 sec on ground
-
Retract: 25 sec in air, 15 sec on ground
4) LE Electric - Extend: 135 sec, or 5 sec to leave retracted position on ground
-Retract: 135 sec
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747-400 MAINTENANCE MANUAL
(e)
An additional time delay of 30 seconds for the TE flap hydraulic disagree is begun when the landing gear control lever is moved from UP to DN.
(6)
Alternate Electric Mode
(a)
In alternate electric mode, the flap drive electric motors are under manual control independent of the FCU's. The flaps are controlled from two switches on the pilots' center instrument panel. The ALTN FLAPS ARM switch is pressed to enable the alternate system.
(b)
Two of the three flap control unit inputs are from the relays R7774, ALT FLAP SW RLY NO. 1, and R7775, ALT FLAP SW RLY NO. 2. The circuit breakers TE FLAP ELEC CONT OTBD and TE FLAP ELEC CONT INBD supply power to these relays. If these two circuit breakers are open, the flaps will be in the primary mode. If only one of the circuit breakers are open, the flaps will be in the alternate mode. A FLAPS CONTROL EICAS caution message will be displayed when the flap system is in the alternate mode.
(c)
The ALTN FLAPS EXT/RET switch is placed in the EXT or RET position to activate the relays which power the electric motors. The relays are deactivated when the limit switches in the TE power packages and the LE power drive units open at flaps fully extended or retracted. The flaps may be stopped at any intermediate position by placing the ALTN FLAPS EXT/RET switch to OFF.
(d)
In alternate electric mode, the extend limit switches in the TE power packages do not allow the TE flaps to extend beyond the 25-unit position.
(7)
Flap Uncommanded Motion / Moving Away / Asymmetry
(a)
If a flap group moves when not commanded, or moves in the opposite direction of that commanded (flaps moving away), the FCU sets an uncommanded motion. If the uncommanded motion is set when the group is in primary hydraulic/pneumatic mode, the FCU switches that group to primary electric mode. If the uncommanded motion is set while the flap group is in primary electric mode, the FCU will shut down that group. The group will remain shut down until power to the FCU's is cycled off and on following the flight.
(b)
The times delays for the FCU to set an uncommanded motion are: 1) TE Hydraulic: 0.5 sec 2) TE Electric: 4.0 sec 3) LE Pneumatic: 0.3 sec 4) LE Electric: 3.0 sec
(c)
If the FCU detects an asymmetry between left wing and right wing flaps of a TE flap group, the FCU will shut down both the hydraulic and electric drives for that group.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL
(8) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 飞行操纵 FLIGHT CONTROLS 7(42)
