Flight Controls - Spoilers Show Schematic only

Amendment: Speedbrake Load Alleviation System included.

Spoilers and Speedbrakes Hydraulics Hydraulics Hydraulics Hydraulics Ailerons Ailerons default

Spoilers

There are six spoiler panels located on the upper wing surface of each wing just forward of the trailing edge flaps. Spoilers on opposing wings are symmetrically paired.

Spoiler panels are used as speedbrakes to increase drag and reduce lift, both in flight and on the ground. The spoilers also supplement roll control in response to control wheel commands. In flight, only five pairs of spoilers are used. On the ground, all six spoiler panels function as ground speedbrakes.

The Control Wheels and the Speedbrake Lever send signals to the spoiler controller. The spoiler controller combines the signals from the Control Wheels and the Speedbrake Lever, determines the required spoiler panel deflection and then signals the spoiler panel actuators to operate. A separate hydraulic actuator powers each spoiler panel.

Speedbrake Load Alleviation System

Speedbrake load alleviation system operates in flight when these conditions occur at the same time:

  • Flaps are UP and
  • Gross weight is greater than 100,243 kg (221,000 lb) and
  • Indicated airspeed is greater than 330 knots

If the SPEEDBRAKE lever is beyond the 50% position it will automatically move to 50% position. If the SPEEDBRAKE LEVER lever is DOWN, an attempt to move it past the 50% position will be restricted. In either case the pilot may override the SPEEDBRAKE lever restriction by applying additional force to the SPEEDBRAKE lever

When gross weight becomes less than 99,790 kg (220,000 lb) or airspeed becomes less than 325 knots, the load alleviation system deactivates and the SPEEDBRAKE lever movement is unrestricted.

Spoiler Speedbrake Operation

Speedbrake Lever

The speedbrakes are controlled by the Speedbrake lever located on the control stand. The speedbrake lever has three / four marked positions:

The speedbrake lever can be placed in intermediate positions between ARMED and UP.

The speedbrake lever can be placed in intermediate positions between ARMED and UP, however, the speedbrake Load Alleviation System may limit lever placement to 50% or less.

Speedbrakes ARMED

In the ARMED position, the speedbrake lever is driven aft to the UP position and the spoiler panels are fully extended when:

Following automatic speedbrake extension, if any of the three conditions are no longer met, the Speedbrake Lever moves to the DOWN position and the spoiler panels retract.

Speedbrakes AUTO Operation

On the ground, the speedbrake lever is driven aft to the UP position and the spoiler panels are fully extended, when either:

The speedbrake lever does not need to be in the ARMED position for automatic operation to occur.

Non-Normal Indications

Speed Brakes Warning The EICAS caution message SPEEDBRAKES EXT displays and the SPEEDBRAKES light illuminates if speedbrakes are extended when either:

Note: The warning is inhibited below 15 ft Radio Altitude.

Auto Speedbrake Warning

The AUTO SPDBRK light illuminates and the EICAS advisory message AUTO SPEEDBRAKE displays to indicate a fault is detected in the automatic speedbrake system which may result in the loss of automatic speedbrake extension. If the speedbrake lever is armed, the message and light indicate a fault which may result in an inadvertent speedbrake extension in flight. The speedbrake lever should be returned to the DOWN position. The speedbrakes can still be operated manually.

Spoilers Warning

The SPOILERS light illuminates and the EICAS advisory message SPOILERS displays to indicate that one or more spoiler pairs are inoperative.

Flaps and Slats