(c)
As the lever passes a point approximately 25% from FLIGHT DETENT to UP, the output rod to the ground spoiler control valve opens the second port on the valve. This extends ground spoiler 6 and 7 from 20° to 45° at one point of control lever travel. This also applies hydraulic pressure to flight spoiler 5 and 8 ratio changer actuators, and flight spoilers 5 and 8 extend from 20° to 45° at the same point of lever travel.
(7)
Automatic Speed Brake
(a)
The speed brake control system automatically extends all spoilers to 45° after touchdown if the speed brake control lever is in the ARM position. The automatic speed brake actuator moves the quadrant of the speed brake drum mechanism to the position corresponding to control lever UP. The actuator is energized to extend when the speed brake control lever is out of the DN detent, both air/ground relay systems are in ground mode, hydraulic system 1 or 4 is pressurized, and thrust levers 1 and 3 are at idle.
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(b)
If the speed brake control lever is in the DN position at touchdown or during a refused takeoff, the spoilers will automatically extend when reverse thrust lever 2 or 4 is moved to the deployed position. When moved to the deployed position, reverse thrust levers 2 and 4 rotate a shaft with a linkage which lifts the speed brake control lever out of the DN detent. The linkage also operates the reverse thrust lever switch. This switch bypasses the auto speedbrake arm switch and extends the auto speed brake actuator.
(c)
During a go-around, all spoilers will automatically retract when either thrust lever 1 or 3 is advanced to the takeoff range.
(8)
The EICAS advisory message SPEEDBRAKE AUTO is displayed along with the status message SPEEDBRAKE AUTO if one or more of the following conditions exist:
(a)
Auto speed brake arming switch is not in armed position when the auto speedbrake actuator is not retracted.
(b)
28v dc power to automatic speed brake control circuit is lost.
(c)
There is a disagreement between primary and alternate air/ground relay systems.
(9)
The EICAS caution message >SPEEDBRAKES EXT is displayed if the speed brake control lever is aft of the ARM position and one or more of the following conditions exist:
(a)
Flaps are in landing position (trailing edge flaps at 25 or 30 units) and radio altitude is greater than 15 feet.
(b)
Airplane radio altitude is between 15 feet and 800 feet.
(c)
Two or more thrust levers are at least 5° above idle stop when airplane radio altitude is valid and is above 15 feet.
(10)
The EICAS warning message >CONFIG SPOILERS is displayed if the speed brake control lever is not in the DN position when N1 of engines 2 and 3 are in the takeoff range and 3 of the 4 fuel switches are on. There will also be an aural warning.
B.
Control
(1)
Manual Speed Brake Operation
(a)
Provide electrical power (Ref 24-22-00/201).
WARNING: BEFORE PROVIDING HYDRAULIC POWER, CHECK THAT PERSONNEL AND
_______ EQUIPMENT ARE CLEAR OF ALL FLIGHT CONTROL SURFACES. TRAILING EDGE FLAP, AILERON, SPOILER, RUDDER AND ELEVATOR CONTROL SURFACES ARE FULLY POWERED. ISOLATE ANY SYSTEM NOT INTENDED FOR OPERATION TO PREVENT INJURY TO PERSONNEL OR DAMAGE TO EQUIPMENT.
(b)
Provide systems 2, 3, and 4 hydraulic power (Ref 29-11-00/201).
(c)
Check that the control wheels are in neutral.
(d)
Move speed brake control lever to FLIGHT DETENT. Flight spoilers 3, 4, 9, and 10 will extend to 45° and ground spoilers 5, 6, 7, and 8 will extend to 20°.
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(e) Move speed brake control lever to UP. All spoilers will extend to 45°. 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 6(105)
