737 Flight Crew Operations Manual
Flight Controls -
System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
D6-27370-866-EGP 9.20.15
Speed Brakes
The speed brakes consist of flight spoilers and ground spoilers. Hydraulic system
A powers all four ground spoilers, two on the upper surface of each wing. The
SPEED BRAKE lever controls the spoilers. When the SPEED BRAKE lever is
actuated all the spoilers extend when the airplane is on the ground and only the
flight spoilers extend when the airplane is in the air.
The SPEEDBRAKES EXTENDED light provides an indication of spoiler
operation in-flight and on the ground. In-flight, the light illuminates to warn the
crew that the speed brakes are extended while in the landing configuration or
below 800 feet AGL. On the ground, the light illuminates when hydraulic pressure
is sensed in the ground spoiler shutoff valve with the speed brake lever in the
DOWN position.
In-Flight Operation
Operating the SPEED BRAKE lever in flight causes all flight spoiler panels to rise
symmetrically to act as speed brakes. Caution should be exercised when
deploying flight spoilers during a turn, as they greatly increase roll rate. When the
speed brakes are in an intermediate position roll rates increase significantly.
Moving the SPEED BRAKE lever beyond the FLIGHT DETENT causes
buffeting and is prohibited in flight.
A lever stop feature is incorporated into the SPEED BRAKE lever mechanism.
The lever stop prevents the SPEED BRAKE lever from being moved beyond the
FLIGHT DETENT when the airplane is in flight with the flaps up. In the event of
the loss of electrical power the lever stop is removed and full speed brake lever
movement is available.
Ground Operation
During landing, the auto speed brake system operates when these conditions
occur:
• SPEED BRAKE lever is in the ARMED position
• SPEED BRAKE ARMED light is illuminated
• radio altitude is less than 10 feet
• landing gear strut compresses on touchdown
Note: Compression of any landing gear strut enables the flight spoilers to
deploy. Compression of the right main landing gear strut enables the
ground spoilers to deploy.
• both thrust levers are retarded to IDLE
• main landing gear wheels spin up (more than 60 kts).
September 26, 2013
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