What happened
Following clearance for takeoff, the pilot activated the aircraft's transponder and strobe lights. Within approximately two to five seconds of this activation, a minor explosion occurred, and fire quickly spread to encompass the right wing. The aircraft had a documented recent history of fuel leaks occurring in the right wing.
The investigation
Investigators reviewed maintenance records and found that Airworthiness Directive (AD) 74-24-03 had not been completed. This specific directive required the deactivation of the strobe light system to prevent the potential ignition of flammable fluids or vapors caused by arcing between the strobe light and the aircraft structure. Additionally, the operator's Approved Aircraft Inspection Program (AAIP) lacked provisions for inspecting fuel systems and related components. Following the event, the FAA issued directives to revise the AAIP to include routine inspections of these critical systems.