Flight Controls - Spoilers 
- Limitations - Flight Controls
- Control Wheel vs Control Surface Deflection
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.
Spoiler Speedbrake Operation
The speedbrakes are controlled by the Speedbrake lever located on the control stand. The speedbrake lever has three marked positions:
- DOWN: Placing the lever in the DOWN detent signals all spoiler panels to the full down (retracted) position..
- ARMED.
- UP: Moving the Speedbrake Lever to the UP position signals spoiler panels to raise to the full up position. The speedbrakes extend to a greater maximum angle on the ground than inflight.
The speedbrake lever can be placed in intermediate positions between ARMED and UP.
Speedbrakes ARMED
In the ARMED position, the speedbrake lever is driven aft to the UP position and the spoiler panels are fully extended when:
- there is hydraulic pressure to both Landing Gear truck tilt actuators and
- the landing gear is fully on the ground (both Truck Tilt Sensors not tilted) and
- both Thrust Levers are at idle.
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:
- there is hydraulic pressure to both Landing Gear truck tilt actuators and
- the landing gear is fully on the ground (both Truck Tilt Sensors not tilted) and
- both Thrust Levers are at idle or
- either reverse thrust lever is moved to the reverse idle detent.
The speedbrake lever does not need to be in the ARMED position for automatic operation to occur.
Non-Normal Indications
The EICAS caution message SPEEDBRAKES EXT displays and the SPEEDBRAKES light illuminates if speedbrakes are extended when either:
- the flaps are in a landing position (25/30) or
- Captain's Radio Altitude is 800 feet or below.
Note: The warning is inhibited below 15 ft Radio Altitude.
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.
The SPOILERS light illuminates and the EICAS advisory message SPOILERS displays to indicate that one or more spoiler pairs are inoperative.
