-access to <APU DATA> via function 5R.
 (a) <APU DATA> This gives access to operational data of the APU, i.e.
 -hours in ECS mode,
 -
number of cold starts,

 -
number of high altitude starts,

 -....

 H.
 LRU Faults, Shutdowns and Fault Tree, Fault Code Numbers (FCN) Three classes of LRU faults exist, class 1 are the most serious and class 3 are the least serious. When certain class 1 LRU faults are detected, the ECB initiates an APU shutdown (if not inhibited) due to the impact of the failed LRU on the overall system operation. The class of the LRU faults and the text, sent to the CFDS, are shown in table 2, 3 and 4. The protective shutdowns with their associated text, shown on the APU shutdown page of the CFDS, are presented in table 5.

 The fault tree (table 5, col. 3) is used to associate a protective
 shutdown with a failed LRU that caused the shutdown. The fault tree is
 used in the following manner:
 If a protective shutdown occurs, the ECB search the fault tree for this
 particular shutdown. Once the shutdown is located, the ECB shall compare
 any failed LRUs that where detected on the current APU run with the LRU
 faults associated with the shutdown reason. If a failed LRU matches one
 of the LRUs associated with the shutdown reason, the failed LRU is
 displayed together with the shutdown reason on the APU shutdown page of
 the CFDS. If no current failed LRU matches an LRU associated with a
 particular shutdown reason, the ECB displays the shutdown reason and a
 list of LRUs which most probably caused the APU to shutdown (table 5,
 col. 2).

 A fixed Fault Code Number (FCN) is allocated to each detectable fault.
 Each FCN (with some exceptions) is linked to a CFDS maintenance message.
 Both, the FCN and the CFDS maintenance message, are shown the LAST LEG
 REPORT, PREVIOUS FLIGHT REPORT etc..
 In many occasions two or more FCNs are linked to the same CFDS message.
 This happens when different FCNs (faults) are in conjunction with the
 same Line Replaceable Unit (LRU).

 Example:

 -------------------------------------------------------------------------------
FCN | Fault Description | CFDS Message | Class ----+----------------------------------------+-------------------------+-------021 | Inlet Press. Sensor shows out of range | INLET PRESS XDCR(8048KM)| 2 ----+----------------------------------------+-------------------------+-------022 | Inlet Press. Sensor shows < 8 psia | INLET PRESS XDCR(8048KM)| 2
 | on ground | | ----+----------------------------------------+-------------------------+-------023 | Inlet Press. Sensor shows out of range | INLET PRESS XDCR(8048KM)| 2
 | low | | ----+----------------------------------------+-------------------------+-------024 | Inlet Press. Sensor shows out of range | INLET PRESS XDCR(8048KM)| 2
 | high | |
 You can find complete enumeration of all FCNs with their associated CFDS messages in Table 6.
 J. BITE Detection
 (1) CLASS 1 Faults
 Table 2
 -------------------------------------------------------------------------------Text for CFDS Indication | ATA | BITE Detection (Failed LRUs) ============================+==========+======================================= POWER SUPPLY INTERRUPT | 24-00-00 | Power Supply Interrupt
 ----------------------------+----------+---------------------------------------CHECK PRESS XDCR WIRING | 49-11-15 | Press XDCR wiring shows open circuit (8001KM) | |
 ----------------------------+----------+---------------------------------------CHECK PRESS XDCR WIRING/ | 49-11-15 | Press XDCR wiring open (800KM1) / ECB (59KD) | | or ECB internal failure
 ----------------------------+----------+---------------------------------------AIR INTAKE FLAP ACTUATOR | 49-16-51 | Inlet Flap shows Flap open high (4015KM) | | current
 | | Inlet Flap shows Flap failed to open | | Inlet Flap shows Flap loss of open | | indication
 ----------------------------+----------+---------------------------------------CHECK IGV ASSEMBLY/ | 49-23-00 | IGV Position disagrees with command IGV ACTUATOR (8014KM) | |
 ----------------------------+----------+---------------------------------------IGV ACTUATOR (8014KM) | 49-23-51 | IGV Torque Motor shows open/short | | circuit ----------------------------+----------+---------------------------------------IGV ACTUATOR (8014KM)/ | 49-23-51 | No LRU detected

 -------------------------------------------------------------------------------
Text for CFDS Indication | ATA | BITE Detection (Failed LRUs) ============================+==========+======================================= FCU (8022KM) / ECB (59KD) | | ----------------------------+----------+---------------------------------------
　
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