The cause of the fire in Cincinatti was never determined, but a connection was suggested to the lav flush motors because breakers had apparently tripped their 11 minutes before the initial fire warning. Also, this incident can not be called a CRASH ,because the plane laned safely, and have the people got out, and THEN the fire flared up and killed 23 people. Air Canada's only real CRASH was in 1973 (I Think), the DC-8 at YYZ, crew error, but also a bit of a design error by Douglas. Their only other fatal incident was a DC-9 (the one delivered right before the cincinatti one, incidentally), in 1978, that overran the runway at YYZ after an aborted takeoff, with two dead.
Next flight.... who knows.