(b)
Data Input Routine monitors the option pins to determine the computer configuration (center FCC and right FMC). It checks for fault data from any installed computer that has the desired ARINC label and store data bit set. It continues the check for fault data until all the store data bits are set or the AUTO ON three minute timer expires.
(c)
Flight Consolidation Routine determines the flight deck effect message and LRU fault message associated with faults received from the six computers. The flight deck effect code is bits 26 through 28 of ARINC label 356 words 2 through 6. The flight deck effect message displayed on line one of the MCDP display is based on priority grouping of the messages. The flight deck effect code is stored in the affected computer. The LRU group code is contained in bits 9 through 16 of ARINC label 356 words 2 through 6. The LRU message is displayed on line two of the MCDP display. The LRU message is based on 20 activity logic routines that monitor the incoming data. The activity logic routines determine when a fault is received from two or more computers. This prevents the fault from being displayed more than once per fault flight.
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FCC L
MCDP (FCC L + FCC C + FCC R) . (FMC L + FMC R + TMC) = IRU R (SINGLE FAULT)
EXAMPLE - RIGHT IRU FAILURE
FCC L
(FCC L + FCC C + FCC R) . (FMC L + FMC R + TMC)= IRU R/TMC (GROUP FAULT)
EXAMPLE - GROUP FAULT
LRU Fault Consolidation Figure 8
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MAINTENANCE MANUAL
(d)
The MCDP consolidation routine uses twenty activity logic routines in processing the LRU/Group fault codes received from the six computers. The six computers receive sensor data on two separate buses. Each activity routine sets a combination of four logic flags which are used to isolate the fault. The logic flags are set based on which computers report the same LRU/Group fault code in words 2 through 6 and the status of the corresponding activity bits in word seven.
(e)
The MCDP display a group fault when the fault cannot be isolated to a single LRU. To accurately determine a faulty LRU, the MCDP must receive the same LRU/Group fault code from two computers using separate buses from the same sensor. Therefore the MCDP displays a group fault message (i.e. IRU R/TMC). The unit on the right of the slash mark is the receiving unit. A group fault indicates a possible wiring problem. The corresponding failure word diagnostic can be displayed along with the intermittant bit.
(f)
Store Fault Data Routine is used to store the flight faults in non-volatile memory (EAROM). The store routine monitors word one of the ARINC word group for STORE DATA bit to be set. When the bit is set, the fault data, LRU GROUP CODE, and flight deck effect for that computer is stored in EAROM. The store routine controls the flight segment index by updating the previous flight faults segment number to include the latest flight. The segment numbers are assigned 00 to 99. The flight segment after 99 goes to 00 and the fault data that was in segment 99 is erased. The completion of the store routine resets the power flip-flop signal. This causes a power-down routine. If the store routine does not reset the flip-flop within three minutes, the three minute timer causes a power-down.
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