Amateur-built LANCAIR 360 N123ST accident near Williams, California

Probable cause

An in-flight fire due to an electrical short circuit.

NTSB analysis

Having leveled off at cruise altitude, the passenger began to smell an electrical burning odor in the experimental airplane's cabin. Smoke then began to stream from the lower center console to the right of the pilot’s footwell. The passenger attempted to locate the source of the smoke while the pilot initiated an emergency descent. Shortly before landing, the footwell became engulfed in flames. During the landing flare, the airplane struck a group of trees and collided with a berm.

The majority of the airplane was consumed by fire; however, examination of the electrical wiring revealed arcing damage to one of the primary electrical supply lines in the area where the passenger reported the first traces of smoke. The wire connected the master solenoid to the airplane’s main system bus.

It is most likely that the wire’s insulation had become compromised, leading to its electrical conductor coming into contact with a metallic airframe component, resulting in a short circuit and fire. The pilot shut off the master solenoid during the descent, which would have halted the short circuit; but by then the fire had most likely already spread, possibly igniting the fuel supply components in that area. The fact that the master solenoid was off also negated the possibility that the short circuit occurred during the ground impact sequence.

The airplane’s construction consisted of automotive electrical wire and household PVC tubing for electrical conduit. Additionally, the battery and associated master solenoid wiring had been relocated three times since the airplane’s completion; however, it could not be determined if this construction or modification caused or contributed to the short circuit.

Text from the NTSB. Open the NTSB docket for WPR13LA122 for the full record.