Air Canada Flight 797 4
Air Canada Flight 797 4 : (2) NTSB Investigation: Though the fuselage was nearly destroyed by the intensity of the fire, the cockpit voice recorder (CVR) and flight data recorder (FDR) for flight 797 were still in good condition and produced vital useful data for the subsequent National Transportation Safety Board (NTSB) investigation. On the CVR, NTSB investigators heard eight sounds of electrical arcinglikely inaudible to the crewbeginning at 18: 48 CDT. Three minutes later, at 18: 51, the popping sounds that Cameron and Ouimet would later identify as the left toilet circuit breaker tripping are audible on the CVR; Cameron attempts to reset the circuits twice over the next 60 seconds, but the CVR records the breakers immediately popping again after each reset attempt. Cameron would attempt once more to reset the breakers at 18: 59, but the CVR records arcing sounds followed by the popping sound of the breakers continuing to trip again after each reset over the next 60 seconds. At 19: 02, the CVR records Flight Attendant Judi Davidson entering the cockpit to deliver the first report of a possible fire in the lavatory. Though a number of wires in the lavatory section were later found with insulation stripped away, NTSB investigators were unable to determine whether this insulation damage was the cause of the fire or was caused by the fire. This particular DC-9 had experienced a number of problems over the months leading up to the incident; 76 maintenance reports had been filed in the plane's logs in the previous year, and the CVR records Cameron telling Ouimet to "put[the tripping breakers] in the book there" when the breakers fail to respond to the first reset attempt at 18: 52
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