27-61-00
ALL ú ú 01 Page 7 ú Jun 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
6. Inboard Flight Spoiler Ratio Changer Actuator
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A. The inboard flight spoiler ratio changer actuator is a two-position, hydraulically driven piston actuator. It allows the No. 5 and 8 flight spoilers to extend to 45 degrees when used as ground speed brakes. An identical actuator is installed in the control package input linkage for the No. 5 and 8 flight spoilers. When the speed brake control lever is in the DOWN or FLIGHT position, the actuator is retracted, with hydraulic system No. 4 pressure on one side of the piston. In this position, spoiler up travel is restricted to 20 degrees. When the lever is in the UP position, the ground spoiler control valve provides hydraulic pressure to the other side of the piston. Due to unequal areas, hydraulic force extends the actuator. This extension provides an additional input to the flight spoiler control package, enabling it to rise 45 degrees.
7. Operation (Fig. 4)
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A. Functional Description
(1)
Rotation of the aileron control wheels provides a manual input which is transferred by the lateral control cable system to the central control actuators. The actuators are dual tandem with a through piston rod having connections on both ends. One end of the piston rod of the actuator connects to a spoiler control differential mechanism. The other end of the piston rod connects to an aileron programmer. The input cranks to the central control actuators are connected together by a force limiting pushrod. The flight spoilers assist the ailerons in providing lateral control. A given control wheel deflection modulates deflection of the appropriate spoilers.
(2)
The left central control actuator provides input to the spoiler control differential mechanism controlling spoilers No. 3, 4, 5, 8, 9 and 10. The right central control actuator provides input to the spoiler control differential mechanism controlling spoilers No. 1, 2, 11 and 12. The output from each spoiler control differential mechanism is directed by control cables and quandrants to the control valves on the various flight spoiler control package. Each flight spoiler control package installation includes a cable quadrant and linkage for conveying the control input to the control package valve. Certain spoilers are grouped together for simultaneous operation by common cable runs from the differential mechanisms. One cable quadrant of the left differential mechanism controls spoilers No. 3, 4 and 5 by the associated cable run. The other cable quadrant of the left differential mechanism controls spoilers No. 8, 9 and 10. One cable quadrant of the right differential mechanism controls spoilers No. 1 and 2 and the other cable quadrant controls spoilers No. 11 and 12. The speed brake control lever on the pilots' control stand drives the speed brake sequence mechanism by means of cables and quadrants. Levers on the speed brake sequence mechanism provide for use of spoilers No. 3 thru 10 as flight speed brakes, and for use of all spoilers No. 1 thru 12, as ground speed brakes.
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27-61-00
ALL ú ú 02 Page 8 ú Feb 10/89
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
GROUND
INBOARD
SPOILER
TO GROUND SPOILER CONTROL VALVE
SPOILER CONTROLS - LEFT WING (RIGHT WING OPPOSITE)
Spoiler Control System Schematic
Figure 4 (Sheet 1)
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