Chaffed Wire
A320
Dispatched with Engine 2 Igniter System A inop under MEL - requiring manual start. The flight was normal until landing.
Symptoms:
During landing with full reverse, an ECAM ENG 2 REV FAULT occurred but the reverser operated normally with no asymmetry.
After landing the APU failed to start and gave an ECAM APU FAULT - APU AUTO SHUTDOWN
On stand, ground power was supplied but tripped off after shutdown and was restored a few seconds later. As the power came on a long series of cautions and warnings appeared on the ECAM, most of which we attributed to the power transfer.
Maintenance action:
APU igniter box fault was deferred and ENG 2 Reverser was locked out.
Departure Attempt 1:
An external air manual start was conducted to a stable idle condition, then a bunch of things happened.
Symptoms:
Then an ECAM ELAC 1 PITCH FAULT occurred, followed by ENG 2 REV FAULT and Engine two Oil pressure indication was lost from the System Display.
Maintenance Action Two:
Engine 2 No4 bearing oil pressure sensor found to be U/S with C/B popped, it was deferred in the tech log.
All flight control power supplies were reset.
Departure Attempt 2:
Engine two started the same way to a stable idle condition then a series of ECAM warnings occurred,
ELAC 1 PITCH FAULT - pilot reset; then
MASTER WARNING ELEV L + R FAULT, ENG 2 REV FAULT, SDAC FAULT and a few others I can't remember - engineer guided resets carried out to no avail.
Maintenance action three:
ELAC 1 suspected to be faulty, deactivated and all other computers reset.
The engineers advised there would be a bunch of faults but they would be spurious and can be reset.
Departure attempt 3:
After start: MASTER WARNING ELEV L + R FAULT occurred but cleared after ELAC 2 and SEC 1, 2 & 3 resets carried out.
The flight control check was normal and the flight proceeded normally albeit 4 hours late with very angry pax.
Solution (finally found a few days later):
ELAC 1 was suspected and after deactivation stopped all of the warnings but after all flight control computers were replaced the problem reoccurred! Further investigation found a chaffed wire (IIRC between ENG 2 and ELAC 1) was shorting out the computers.