Incident Details
During the initial climb of a dual instructional flight, a fire erupted behind the instrument panel. The aircraft was returned for landing. During the roll-out, flames approximately six inches long, smoke, and noxious fumes filled the cockpit. When the aircraft slowed to 10 mph, both pilots exited the aircraft. Thereafter, the aircraft was destroyed by fire.
Examination Findings
Examination of the aircraft revealed that the 15-amp rated wire designated 'DA1' had shorted and fused onto the carburetor heat control lever. Wire DA1 routes current between the ammeter, the flap switch, and the circuit breaker/bus terminal connector.
Maintenance Context
During manufacture of the aircraft, wire DA1 is not routed against the carburetor heat control lever. However, during maintenance of the nearby gear selector lines, wire DA1 could be improperly rerouted and thus pressed against the carburetor control lever. This may result in eventual wear and electrical shorting.