Incident Overview
On 17 March 2003, a Piper PA-25-235 Pawnee (registration G-BFSC) experienced an in-flight engine failure and fire during a familiarisation flight at North Weald Aerodrome, Essex. The aircraft, manufactured in 1976, was powered by a single Lycoming O-540-B2C5 piston engine. The sole occupant, a 76-year-old private pilot with 4,355 total flying hours (33 on type), was performing the final familiarisation flight of the day.
History of Flight
The aircraft had recently been delivered to a gliding club after an extended period of low usage. Between delivery in February 2003 and the incident, the club's tug pilots had accumulated about 12 hours of familiarisation. The pilot, familiar with the PA-25 Pawnee, was on the first climb-out when, at approximately 700 feet, the engine suddenly lost power and the cockpit filled with smoke. He immediately notified North Weald Radio, announced a downwind landing on the runway he had just departed, and turned off the fuel and electrical switches. He completed a successful dead-stick landing, with a large amount of smoke emanating from the engine compartment. Local fire services arrived, but personnel at the airfield extinguished the fire within about five minutes.
Investigation Findings
Examination of the aircraft revealed that the fire in the engine compartment originated from a large fracture in the muffler section of the engine exhaust. The hole in the top of the muffler was approximately 10 cm in diameter. Escaping hot gases ignited combustible materials in the engine bay, including the ignition harness, resulting in a sudden and complete loss of engine power. The engineer repairing the aircraft had not encountered such damage before and considered an exhaust backfire shortly before the incident flight to be the most likely cause.
The aircraft, manufactured in 1976, had accumulated less than 40 total operating hours over its 27-year life, having spent most of that time in storage in the UK as a reserve for agricultural operations. The engineer noted corrosion inside the exhaust system, likely from long-term storage, which would have made the muffler more vulnerable to damage from an exhaust backfire.