32-09-03
ALL ú ú 01 Page 9 ú Jan 28/02
OUTPUT N.C.
OUTPUT N.O.
RELAY (TYP)ATA
/
A
DBITE
RD
CARDS
/A
BITE D
CARDS
RS
BUNEAR
LOGIC
= 0
S FAR = 1
GATES FAULT = 1 DIS GND = 0 DIS OPENOR 28V = 1
LOGIC CARD (TYP 3 PLCS)
A
DBITE
AT
CARDS
A
28V DC
(TYP)
CB PNL ASSY PROX CHAN (TYP 16 PLCS)
PROX CARD (TYP 8 PLCS)
PROXIMITY SWITCH ELEX UNIT (PSEU)
TARGET NEAR
TARGET FAR
Proximity Switch System SchematicFigure 4 (Sheet 2)
SCHAN (TYP 3 PLCS)
TYP II DRIVER
BUS
AA
MD & T TYP I DRIVER CHAN
ANN LT (TYP)(TYP 35 PLCS) ANNUNCIATOR PNL
EICAS (TYP)
A
757
MAINTENANCE MANUAL
32-09-03
ALL ú ú 06 Page 10 ú Jan 28/02
A
757
MAINTENANCE MANUAL
(4)
The in-flight mode automatically monitors critical flight outputs shown in Table 2 when both main landing gear are tilted (gear up). The BITE is normally off in flight. If one of the outputs in Table 2 changes to an incorrect state for a period longer than that specified (delay period), the in-flight BITE is activated. A test is then conducted on associated flight-critical circuit and sensors listed in Table 3. Any faults are stored in memory. The in-flight BITE remains active as long as the flight-critical output is incorrect. If no faults are detected (output correct) the in-flight BITE is turned off.
(5)
The BITE section consists of a BITE module and interface elements on each card in the PSEU. Operating controls are located on the front panel of the BITE module. The panel consists of following:
(a)
One 3-digit, 7-segment numeric display - provides digital readout and automatically identifies faulted channel by fault codes listed on the PSEU front panel placard.
(b)
One 3-digit, thumbwheel sensor channel selector - allows manual channel selection of sensor to be tested.
(c)
Five indicator lights labeled as TARGET NEAR, TARGET FAR, SENSOR, CARD, and TARGET. 1) TARGET NEAR and TARGET FAR indicator lights - display
position of target with respect to sensor when TARGET TEST
switch is pressed and sensor channel has been selected. 2) SENSOR indicator light - shows faulty sensor or wires. 3) CARD indicator light - shows faulty card
NOTE: If card fault code (005 or 011) is indicated, check
____ landing gear lever input prior to replacing card. The indication may occur only as a result of an in-flight BITE (BIT switch).
4) TARGET indicator light - shows faulty target state (as determined by target reasonableness test during in-flight BITE or on-ground system verify test).
(d) Five momentary pushbutton switches labeled as PRESS/TEST, VERIFY, TARGET TEST, BIT and RESET. The RESET button is recessed in the panel. 1) PRESS/TEST switch - performs lamp test (code 888 in channel
readout). Clears BIT test if in progress.
2) VERIFY switch - initiates the on-ground system test. Display flashes code CCC during test and code 999 at end of test.
3) TARGET TEST switch - activates sensor test mode. Simultaneous activation with PRESS/TEST switch will turn off BITE power and reset BIT testing.
32-09-03
ALL ú ú 05 Page 11 ú May 28/01
A
757
MAINTENANCE MANUAL
4) BIT switch - initiates memory recall of stored faults. Code 000 displayed if no faults exist or all faults recalled. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 起落架 CHAPTER 32 - LANDING GEAR 1(48)
