G28948
Flap Asymmetry Test Switch 500
27-58-41 Figure 401 May 15/79
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FLIGHT SPOILER CONTROL SYSTEM - DESCRIPTION AND OPERATION
1. General
A. The flight spoiler control system supplements the ailerons in providing lateral control. The spoilers are numbered 1 through 8 from left to right. The flight spoilers, numbers 2, 3, 6, and 7 are located outboard of the engines. (See figure 1.) The ground spoilers 1 and 8 are located furthest outboard on the wings. The ground spoilers, numbers 4 and 5, are located inboard of the engines. (Refer to 27-62-0, Speed Brake Control System, for ground spoiler control.) The spoilers lie flush with the upper wing surface when not in use, and can be raised to various angles when in use. The flight spoilers may also act as speed brakes.
B. When functioning as spoilers, the flight spoiler panels raise on the wing on which the aileron rotates up. The spoiler panels on the down aileron wing remain faired. When used as speed brakes, the spoiler panels on both wings rise. With speed brakes on, the spoiler panels on the up aileron wing will be raised more than those on the down aileron wing. This allows the flight spoilers to provide lateral control and speed brake operation simultaneously.
C. Aileron control wheel rotation directs flight spoiler motion for lateral control. (See figure 2.) Input to the spoiler control system is normally through an aileron spring cartridge that connects the aileron bus drums to a spoiler ratio changer. The spoiler ratio changer reduces the magnitude of the lateral control input to the spoiler control system, when speed brakes are used. The amount of reduction depends on the speed brake lever position, with zero speed brakes giving maximum input. A spoiler mixer combines the lateral control inputs with speed brake inputs to move control cables, which are routed along the rear spars of the wings to spoiler actuator quadrants. The spoiler actuator quadrants position control valves in spoiler actuators and allow hydraulic pressure to position the spoilers. As the actuators move to position the spoilers, the valves are returned to the closed position. This provides a follow-up action such that the spoilers are hydraulically held in the desired position.
D. An auxiliary set of control cables runs from a transfer mechanism at the base of the first officer's control column to a spoiler control quadrant, which also drives the spoiler ratio changer. If a malfunction occurs to restrict operation of the aileron control system, the first officer may transmit lateral control signals to the ratio changer through these cables. When spoiler control is obtained in this manner the first officer is required to override a spring in the transfer mechanism. If a malfunction occurs to restrict operation of the spoiler control system, the captain may override the spring in the transfer mechanism to provide aileron control. See 27-11-0, Aileron and Aileron Trim Control System, for a complete description of the transfer mechanism.
500
Nov 15/67 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 27-61-0 Page 1
G28953G28960
Spoiler Panel Identification 500
27-61-0 Figure 1 Nov 15/67
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
500 Spoiler Control System Component Location
Nov 15/67 Figure 2 27-61-0
Page 3
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
E. Each spoiler is operated by its own actuator. Hydraulic power to operate the spoilers is obtained from hydraulic system B for the outboard flight spoiler on each wing, and from hydraulic system A for the inboard flight spoiler on each wing. Maximum hinge moment on the spoilers is limited by a check valve in each actuator, permitting the spoiler panels to blow down if limiting speed is exceeded with spoilers up.
F. Electric motor-driven shutoff valves, located in the flight controls hydraulic modular packages, allow the flight crew to shut off spoiler hydraulic power from system A, system B, or both systems. The system A flight controls hydraulic modular package is in the left wheel wel1 and the system B flight controls hydraulic modular package is in the right wheel well. Control switches for these two shutoff valves are on the pilots' overhead panel.
2. Flight Spoilers
A. Spoilers raise to provide spoiler action. The spoilers are of bonded honeycomb construction with upper and lower skins of clad aluminum alloy and a nonperforated aluminum honeycomb core. On some airplanes, the spoilers are of graphite/epoxy construction with upper and lower skins of graphite laminate and graphite/epoxy nomex honeycomb core. A continuous phenolic rub strip is bonded to the lower surface at the trailing edge. Dacron covered silicone rubber seals are installed at each end and at the forward edge. The seals at each end are adjustable. The flight spoilers (number 2, 3, 6, and 7) and the outboard ground spoilers (number 1 and 8) are interchangeable among themselves.
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