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Airframes and systems - part 4

Chùm tia là bị cắt ngang lực lượng S, dòng hành động theo một khía cạnh của hình lục giác, như được hiển thị. Tìm tốc độ xoay của chùm tia trong điều kiện thường được, S, và Lô cắt module G. phân phối dòng chảy cắt xung quanh phần, với các giá trị trong của S và a. | LANDING GEAR SYSTEMS AIRCRAFT BRAKES c Locked wheel protection If a wheel locks because of a wet patch or ice the anti-skid controller will release the pressure to that wheel completely until the wheel spins up again and the pressure will be re-applied. To enable the pilot to have full control of the brakes for taxying and manoeuvring the anti-skid system is deactivated either manually or automatically when the aircraft has slowed down to below approximately 20 m.p.h. it is assumed then that there is no further danger of skidding. 4.9 TYPICAL AIRCRAFT WHEEL BRAKE SYSTEM The brakes are powered by one of the aircraft hydraulic power systems system 1 with automatic switch over to an alternate system system 2 in the event of low system 1 pressure. When normal and alternate brake hydraulic sources are lost an accumulator is automatically selected to maintain parking brake pressure. Antiskid Protection The antiskid valves receive hydraulic pressure from the normal brake metering valves or the autobrake valves with the antiskid control unit providing electrical signals to the antiskid valves to control braking during skid conditions. Wheel speed transducers mounted in the axle transmit wheel speed inputs to the antiskid control unit. Each wheel is provided individually with antiskid protection when normal brakes are operative. When skidding is initially detected the antiskid controller commands the respective antiskid valve to reduce brake pressure which protects the wheel from further skidding. Touchdown braking protection is provided by comparing wheel speed to IRS inertial reference system groundspeed. During alternate brake operation antiskid protection is provided to wheel pairs rather than individual wheels. Torque Limiting A brake torque sensor is provided at each wheel to detect excessive torque during braking to prevent damage to the landing gear more a problem with CARBON brakes . When excessive torque stress is detected a signal is sent to the antiskid valve .