(7)
A separate power source provides power for the two BITE cards, the display, and five lights. The thumbwheel sensor channel selector is not lighted.
(8)
A microcomputer in one of the BITE card provides control for all BITE functions.
(9)
The BITE can be used for both in-flight monitoring and on-ground system trouble shooting. Three levels of BITE are provided. These are automatic in-flight monitoring, on-ground system test, and sensor target position test.
(10)
Automatic in-flight monitoring
(a)
The in-flight monitoring is automatically activated whenever specific outputs listed in Table 2 are incorrect. Normally during flight, the BITE section is turned off. However, if any flight critical output changes to an incorrect state, BITE power is turned on and a timer activated. If the output is incorrect for a period greater than the delay specified in Table 2, sensors are checked for open and short circuits. Input discrepancies are checked by initiating a target position reasonableness test for those groups of sensors listed for "In-Flight BITE" in Table 3. Fault codes are entered and stored indefinately in memory.
(b)
Recall of fault codes and fault type indication is accomplished by repeatedly pressing the BIT switch. Fault recalls are on a last-in/first-out basis. Code 000 is displayed when no fault codes are present or all entries have been recalled. All panel indicators are turned off 2 minutes after turn on. Erasure of memory contents is provided by pressing the RESET switch. Code EEE is displayed during erasure.
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MAINTENANCE MANUAL
~.............................................................................. | Table 2 | | Flight-Critical Outputs | ................................................................................ | Flight Outputs | Delay Period (Seconds)| ................................................................................
| | |
| 1. Thrust reverser in transit - L engine | 5 |
| 2. Thurst reverser in transit - R engine | 5 |
| 3. Any access door unsafe | 2 |
| 4. Any cargo door unsafe | 2 |
| 5. Any entry door unsafe | 2 |
| 6. Any emergency door unsafe | 2 |
| 7. Any gear not in selected position (System No. 1) | 60 |
| 8. Any gear not in selected position (System No. 2) | 60 |
| 9. On ground (System No. 2) | 5 |
| 10. On ground (System No. 1) | 5 |
| 11. Nose gear compressed (System No. 1) | 5 |
| 12. Nose gear compressed (System No. 2) | 5 |
2......................................................….......................1
(11)
On-ground system test
(a)
On the ground, BITE can be used to perform a complete system test or individual subsystem tests. Both the complete system test and subsystem test verify BITE circuit functions, sensors and sensor wiring, logic, and drivers. They also perform a target position reasonableness test on sensors listed for "Ground BITE" in Table 3.
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