Primary finding
Probable cause
The passenger's failure to extinguish a cigarette before placing it into the lavatory waste bin. Factors related to the incident were: an inoperative smoke detector in the lavatory, the manufacturer's inadequate maintenance program, and inadequate review of the maintenance program by the federal aviation administration.
Investigator assessment
Analysis narrative
A passenger had discarded a cigarette before leaving the lavatory. The flight attendant found smoke issuing from the waste bin and extinguished the fire. There was no indication in the cockpit of smoke or fire. A later check of the smoke detector showed it did not activate when smoke was generated in the lavatory. The operator adhered to the aircraft manufacturer's recommended maintenance program; the program contained no procedure or interval for cleaning smoke detectors or ducting. There was no operational test which demostrated a detector could sense smoke.
Source record
Factual narrative
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