Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Flight Deck / Cabin / Aircraft Event Illness / Injury
General Maintenance Action
Aircraft; Human Factors
Just after taking our seats in [the cockpit] the aircraft lost electrical power. I looked at the overhead and noted that ground power was available and selected it on. (I presumed a bad ground power connection at first.) As my eyes passed across the overhead panel I noted and the First Officer verbalized a fault light on the APU master switch. Shortly thereafter; we got an APU AUTOSHUTDOWN ECAM. We followed ECAM procedures and contacted Maintenance. The APU was put on MEL and during that process; we noted a green flashing low APU [oil]. We pointed it out to the mechanic; but thought little of it at the time.After shutting down at our destination; the first flight attendant; informed us that on two of the previous three legs prior to ours; there had been fumes in the cabin that were so strong that passengers were covering their mouths and noses in an attempt to avoid the smell. He said he reported the fumes to the Captains in both cases; but that the Captains did nothing about it.Note that we nor the passengers or cabin crew detected any odors during our flight.We contacted Maintenance and explained the situation. I was asked to and did enter a write up in the Aircraft Maintenance Log (AML) and complete an aircraft cabin odor report as best as I could. (Since I was not on the flights where it occurred; I was unable to answer most of the questions on the report.)Maintenance showed up to the aircraft promptly after my call and found that the APU had been leaking oil and it appeared it had run down the skin of the aircraft and reentered at the APU intake.I was later informed that when Maintenance started the APU after my write up; 'flames shot from the back of the APU because the oil leak was so large.'This event occurred because the APU leaked oil and although the flight attendants made the problem known to the prior flight crew; they did not report it to maintenance.While; I'm not in a position to speculate how the first fumes in the cabin encounter could have been avoided; it seems from what I was told that had the first Captain to be notified of the issue made a logbook entry; notified maintenance; and filled an aircraft cabin odor report; the subsequent problems could have been avoided.
A319 Captain reported an APU auto shut down at the gate due to low oil quantity. The APU was deferred; but later; Maintenance determined that leaking oil likely caused fumes in the cabin on previous legs with a different crew.