B777 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 196.43; Flight Crew Total 28000; Flight Crew Type 1196.57
Distraction; Troubleshooting; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Procedure
This APU was deferred due to a large hot air leak in the APU exhaust duct. The leak was only found because the APU needed oil; and the leak was found while adding oil. There is a fire loop here that apparently never detected the leak. This duct leak was NOT new. It looks like it had been there for at least weeks; perhaps months?
A large hot air duct leak was discovered on an MEL'd APU during an oil servicing that was not previously detected by the nearby fire loop.