(a)
The communication port in each wheel card provides the tie-in between cards. A BITE status circuit processes the incoming signal in and out of the self test circuits and provides a BITE status output to the driver circuit. A second BITE status output is OR'd with a failure signal input from other wheel cards to provide a driving signal to the driver circuit.
(5)
Antiskid/Autobrake BITE and fault annunciation schematic (Fig. 17)
(a)
Display card power and annunciation
1) 28 v dc power is provided through the AUTOBK ANTISKID TEST IND 1 and AUTOBK ANTISKID TEST IND 2 circuit breakers on panel P11. The circuit breakers provide power to the autobrake, BITE, and interface/display cards in the control unit.
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2) The interface/display card receives front panel rotary switch position discrete signals thru the panel switch input port. The display card also receives the autobrake discrete signals, the system fault signals (from BITE card), and the wheel card fault signals, thru the BITE/display port.
(b) Display card signal processing 1) The display card, thru data management, processes the discrete and fault signal inputs into the microprocessor. 2) The rotary switch position discrete signals allow the test initiation circuit to generate request commands. The commands are appropriate to its mode of operation (test level) to the wheel cards and autobrake card. Upon receipt, each card responses with the status information requested.
3) When fault is detected, the display card stores the fault in the memory and provides driving signals to the display driver and the fault light driver. The display driver enables the illumination of the display on the control unit (upper half of the display comes on immediately and the lower half follows after three seconds). The fault light driver receives the signal from the fault memory and turns on the ANTISKID light on P5.
(c) Antiskid wheel card signals 1) The BITE self test circuit in each wheel card provides a complete electrical self test to the antiskid system. The test includes component check for continuity and impedance, driver check for circuit failure, and a brake release test. Results of these tests are passed on to the BITE card via the data link. 2) The BITE status test circuit in each wheel card provides a monitoring test upon completion of the self test. The test monitors the following and provides its results to the BITE card: Gear position switch - up/down Transducer interface - operable/nonoperable Digital check sum - active check with memory Wheel velocity - transducer continuity and impedance Valve current bias - electrical response to valves Failure light drivers - continuous operation of light
drivers Digital parity - check digital work parity for correctness
3) The analog signal inputs from the wheel card to the BITE card are the wheel speed transducer voltages, the 26 v dc and 5 v dc regulated power source voltages and valve voltages.
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(d) Autobrake card signals
1) The autobrake card BITE self test circuit provides electrical self test to the autobrake system (airplane in air with the AUTOBRAKES selector switch at 1, 2, 3, 4 or MAX AUTO). The self test circuit also provides a RAMP test (airplane on ground with the switch at RTO). Result of test is passed on to the BITE card via the data link.
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本文链接地址：757 AMM 飞机维护手册 起落架 CHAPTER 32 - LANDING GEAR 3(5)
