MD-11 Flight Crew Operations Manual
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Landing Gear and Brakes -
Description and Operation
Land.10.7
After the ABS initiates braking, normal landing mode braking will continue
regardless of flap setting. Stowing the ground spoilers will release the brake
pressure without disarming the ABS landing mode. ABS DISARM lights will
remain off and automatic braking will again be available if spoilers are deployed.
The ABS takeoff mode is armed by selecting T.O. with the AUTO BRAKE
selector. It is desirable that auto ground spoilers be armed and flaps must be in the
takeoff range.
In the Rejected Takeoff (RTO) mode above 100 knots the ABS provides
maximum brake pressure from both brake system 1 (hyd sys 1) and brake system
2 (hyd sys 3). Maximum individual brake pressure is reduced only by anti-skid
operation. Maximum deceleration is achieved.
RTO initiation must occur at speeds greater than 100 knots for maximum dual
system braking. If RTO is initiated below 100 knots, the ABS reverts to landing
mode operation and MIN braking is applied. The ABS takeoff mode is activated
during a rejected takeoff when automatic or manual ground spoilers are deployed.
If spoilers fail to deploy automatically, manual deployment will activate the ABS.
Once automatic brakes are applied for an RTO, pilot takeover can be initiated by
either advancing throttles 1 or 3 beyond 5 degrees of travel or by depressing the
brake pedals beyond 90 percent of travel for MAX RTO and 40 percent of travel
for MIN RTO. Automatic disarming will cause the ABS DISARM lights on the
glareshield to illuminate.
An ABS malfunction will cause the system to automatically disarm. The ABS
DISARM lights will illuminate and the AUTO BRAKE FAIL alert will be
displayed.
To rearm the ABS system after it has automatically disarmed, the AUTO BRAKE
selector must be moved to the OFF position and then back to a deceleration
setting. If the fault has cleared, the system will rearm. In flight, when the GEAR
handle is up, power to the ABS is removed.
ABS faults are stored in the CFDS.
ABS Deceleration Rates
The CFDS can display the ABS configuration (HIGH ). Approved Flight Manual
(AFM) stopping performance with ABS is available and data used should match
the CFDS display.
November 10, 2008
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