ENG723

Aircraft was flown to [Location] with multiple ADD’s, including FMGC 1 inoperative, and no APU (air start and full ground service required). Inbound crew noted Engine 2 Overspeed Protection Fault appeared on shutdown. MEL consulted — no dispatch. I contacted [Base] engineering and informed them of the occurrence of a nil dispatch fault. Aircraft had previous history of ENG 2 OVRSP PROT ECM 3 days prior [Sector] in tech log. [Base] engineering initially dismissive that aircraft had a previous occurrence of the fault, despite being logged in tech log.

We were attended by 3 experienced [Same Type] engineers in [Location], being [a Foreign Operator’s] main maintenance base. After approximately 2:30 hours of diagnosis and an engine run, the nil-dispatch fault remained on engine shutdown. The local engineers were convinced a bigger underlying issue was leading to the overspeed protection warning triggering when self-testing the FMU on IDG 2 during shutdown. After the first engine run, the local engineers declared the aircraft AOG.

The final solution recommended by [Base] engineering was to disconnect the engine 2 generator, so that the self-test of the fuel metering unit would not occur. Another engine run could then be performed and the ENG 2 OVRSP PROT FAULT nil dispatch ECAM might not appear. This would add an engine 2 generator ADD but might prevent the ECAM caution to enable dispatch to [Base]. However, we would be unable to do this using MEL reference 24-22-01A because dispatch in accordance with that MEL procedure requires 2 operative generators, and the aircraft APU was already inoperative.

To the disbelief of the local engineering team, they were informed that the APU is only ADD’d because it had an oil leak that led to a fumes event. [Base] engineering required the engineers to check that if the APU oil leak is “only minor”, then it “should be OK” to recertify the APU as only inoperative for air bleed and not for electrical generation. This would provide the second generator and get around the limitations of MEL 24-22-01A. By disconnecting IDG 2 and re-performing a second engine run, hopefully the ENG 2 OVRSP PROT FAULT ECAM would not reappear, and the aircraft could legally dispatch.

The Flight Crew had concerns about operating an aircraft at night in thunderstorms with the combination of defects proposed. The aircraft would require air start, with no APU bleed from re-classified INOP APU, and be level-capped through bad weather enroute, only 1 AP/FD due to inoperative FMGC 1, without an ENG 2 generator. I also had concerns that [Base] engineering solutions involved masking the underlying technical issue, rather than operating within the spirit of the MEL. These concerns were compounded by the local engineering team stating that they would feel uncomfortable certifying that aircraft as fit to fly, and that it would be unacceptable for [Foreign Operator] aircraft to have that number of ADDs.

The Flight Crew were unable to contact [Base] operations or flight crew management via any number of provided phone numbers to express our concerns for over 2 hours. The only flight crew point of contact with [Base] was via Engineering, who informed the Captain “We are speaking with operations, but they are too busy to contact you”. During a second engine run with the disconnected IDG 2, on shutdown the nil-dispatch ECAM reappeared, and the aircraft was finally declared AOG.

I had two primary concerns. Firstly, I now have a few years’ experience at [Operator], but this was the first time I’ve encountered that level of dissatisfaction from local engineers. From their differing opinions on continuing the troubleshooting process, to the desire to dispatch an aircraft with that combination of ADDs. Secondly, I found myself unsure around the applicability of MEL nil-dispatch clauses. From my understanding, we were locking out a system to prevent a self-test occurring, which was producing a nil dispatch message. I had a conflict about whether masking a message is an acceptable use of the MEL.