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发表于 2018-4-27 16:29:09
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来自： 中国云南昆明
Issue Description
Following to the Entry Into Service of latest PHC standard PN 733902-1-1, two kinds of ECAM WARNING messages have been experienced by operators:
Case 1: ANTI ICE ALL PITOT FAULT, without associated Fault Message, and associated with the three E/W: ANTI ICE CAPT PROBES, ANTI ICE F/O PROBES, ANTI ICE STBY PROBES.
These E/W trigger at A/C power-up sequence, when the three PHCs are performing their power-up tests and while all the probes are already power supplied.
Case 2: ANTI ICE CAPT AOA E/W without associated Fault Message
This E/W is triggered at A/C power-up sequence.
Note: these E/W (for both cases 1 and 2) only appear after ADIRUs selected on NAV.
Consequence
Case 1&2: These E/W are latched until a PHC reset via C/B or I-BITE is performed. Otherwise a/c dispatch as mentioned in paragraph "Maintenance Advice".
Investigation Status
Case 1: During these power-up tests each PHC performs a power switching functional test of each probe and validates it by measuring the current consumption. But due to power transfers at a/c power-up, these current measurements may be disturbed, and all the PHC discrete outputs are set to FAULT state and latched.
Case 2: The AOA inrush current is monitored by the PHC during 30 sec after the first Engine start (if current < 1 A, a failure is generated).
During power transfer, EIU1 & EIU2 send a spurious signal to the PHC leading to a reset of the AOA monitoring function and to a new monitoring activation. During this second process the current is < 1 A which is as per design for a hot probe. An inrush current failure is then activated by the PHC.
Mitigation / Interim Plan
Case 1&2: A reset of the three PHCs, just after a/c power-on and before ADIRUs selected on NAV, inhibits the triggering of these E/W.
Airbus recommends to apply the following sequence to avoid E/W triggering:
-wait for 40 seconds after a/c power-on (i.e. batteries ON, external power ON),
-pull C/Bs of the PHC1, 2 and 3 (2DA1, 2DA2, 2DA3) during 10 seconds,
-push C/Bs
-select ADIRUs on NAV
Maintenance Information
Case 1: If E/W trigger, perform interactive BITE just after display. If test OK, no more action. If test failed, no dispatch under MMEL and apply TSM 30-31-00-810-868.
Case 2: If E/W triggers, perform interactive BITE just after display. If test OK, no more action. If test failed, dispatch under MMEL 30-31-04C and apply TSM 30-31-00-810-801A.
Repercussion on A/C Dispatch
Please refer to maintenance recommendations for T/S, or ATA30 MMEL for dispatch with probe ice protection system partially inoperative.
Solution
Case 1: A software modification will fix the discrepancy between the PHC channels.
Case 2: A software modification will improve the robustness of the AOA inrush current monitoring to avoid this inadvertent re-activation.
Certification of the PHC PN 733902-1-2 completed mid-November 2012.
Introduction of the new computer:
- in production:
- technical GO AHEAD validated in August 2013 further to a successful EIS of this new PHC version
- standardisation point under definition
- in service, ISE launched with BAW and APJ, on a retrofit basis.
SB 30-1051 validated for all A/C
PN Solution
733902-1-2
OPS Information
N/A |
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