The Boeing Company

Jay S Kallaher

John J Gowan

Thomas Todd Griffith

Trent Daryl Miller

At low speeds, an antiskid/autobrake control system applies a brake release current to the antiskid valves of the brake system associated with selected wheels of an airplane to prevent brake shudder caused by gear walk. The control system obtains a measured wheelspeed value from each of the selected wheels and calculates a reference wheelspeed based the measured wheelspeed. Tests are made to determine if the reference wheelspeed is below some predetermined magnitude, e.g., 15 knots, and if the airplane ground speed is below some predetermined magnitude, e.g., 50 knots. If the tests are passed, the value of a low-speed brake release current to be applied to the antiskid valves of the airplane's brake system is determined. In order to prevent an abrupt change in braking, the low-speed brake release value ramps off as the airplane slows to a stop. Releasing some of the brakes results in the pilot increasing pressure on the remaining brakes, thereby eliminating brake shudder due to gear walk. Preferably, the low-speed brake release signal is only generated if a valid wheelspeed value has been detected in a predetermined period of time, e.g., 0.5 seconds. Further, a low-speed brake release current is generated only if the low-speed brake release current is greater than an antiskid control current.

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Renton, WA, United States of America

Jay S Kallaher