MD-11 Flight Crew Operations Manual
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Landing Gear and Brakes -
Description and Operation
Land.10.5
When the brake system is in park, an amber PARK brake light on the forward
pedestal and a PARK BRAKE ON alert will illuminate.
The parking brakes can be released by fully depressing and then releasing the toe
pedals. Depressurization of the hydraulic system(s) will not effect parking brake
capability. Subsequent pressurizing of the hydraulic system(s) will automatically
reset full parking brake capability regardless of initial parking brake pressure.
During re-pressurization of the parking brake, the PARK BRAKE handle does not
need to be operated or reset.
If throttles 1 and 2 are advanced for takeoff, the ground mechanism is in ground
mode, and parking brake is on, a tone will sound.
Anti-Skid System
The anti-skid system is an automatic, pressure modulating system controlled by
an anti-skid control box, with individual wheel speed transducers, and anti-skid
control valves for each main and center wheel brake. The system prevents tire skid
by reducing individual brake pressure (manual or automatic braking) as required.
Touchdown protection prevents inadvertent brake application on landing.
Automatic brake release of a locked wheel is provided down to speeds of 25 knots.
When the gear is in the up position, power to the anti-skid system is removed.
A continuous anti-skid self test is performed whenever power is supplied to the
anti-skid control unit. A more extensive powerup test is performed whenever the
gear extends down or the ANTI-SKID switch is cycled from off to on.
A failure in the anti-skid system which may affect anti-skid function will cause an
ANTI-SKID L FAIL, ANTI-SKID R FAIL, or ANTI-SKID FAIL alert to be
displayed. Fault/status data is sent to the Centralized Fault Display System
(CFDS).
If a wheel brake or anti-skid channel is inoperative, the aircraft can be dispatched
using the Minimum Equipment List (MEL) procedure and the CFDS. In this case
the alert WHEEL BRAKE INOP will appear as a reminder to the flight crew.
The anti-skid system can be manually disarmed with the ANTI-SKID switch on
the forward pedestal (switch will illuminate OFF).
Center gear brakes are off when brake control valve output pressure is below
about 1,500 psi.
During taxi (below 50 knots), center gear brakes are off and the remaining eight
main gear brakes are symmetrically alternated after each brake application
October 02, 2006
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