Accident Details
On 18 March 2003 at 1250 hrs, a Piper PA-22-150 Caribbean (modified), registration G-APTP, was destroyed by fire at Roughay Farm, Upham, following a fuel leak. The aircraft was engaged in a private flight with only the pilot on board; no injuries occurred.
History of Flight
The pilot intended to check the aircraft systems before a scheduled Star Annual inspection at Old Sarum. Before departure, he added 40 litres of fuel to each main tank (right and left) and 10 litres to the reserve tank. During climb, the pilot tested the reserve fuel transfer system by pulling the reserve fuel knob. A few minutes later, he smelled fuel in the cockpit and immediately switched off the reserve fuel to stop the transfer. He returned to his home airstrip at Roughay Farm and landed without incident.
Fuel Leak and Fire
After landing, the fuel smell intensified. The pilot shut down, exited, and saw fuel dripping from the right rear fuselage. Returning inside, he found the right floor carpet soaked. Removing the forward right seat revealed a leak from a rigid aluminum alloy fuel pipe connecting the reserve tank pump to the right main tank fuel strainer. The leak was a small fan-like spray with weeping. Using tape from his flight bag, the pilot temporarily staunched the leak. He then left to retrieve draining equipment from his car, intending to empty the right main tank. As he prepared the equipment beside the aircraft, it spontaneously burst into flames. The fire started at the front of the cockpit and spread rapidly. The pilot escaped without injury and called the Fire Service. There was no on-site firefighting capability except portable extinguishers. The Fire Service arrived 10-15 minutes later, but the aircraft was largely consumed.
Fire Cause and Pipe Failure
The Fire Service assessed that the fire was caused by fuel vapours ignited by hot spots from the engine. The leaking pipe, original factory fit from 1957, had not been replaced in 46 years and was consumed by the fire, preventing determination of the exact failure cause. The pipe was located in an area free of structure or electrical cabling, making chafing or arcing unlikely. The pilot noted no external corrosion or pitting before the leak. The pipe had last been disturbed during major maintenance in 1993. The reserve tank system was rarely used, and the pipe normally contained fuel at low pressure from the right main tank; stagnant fuel could lead to water contamination and internal corrosion. It is most probable that pressurization during the reserve tank test caused a breach at a weakened point from such corrosion.
Pilot's Comment
The pilot later stated that his actions to staunch the leak and drain the tank were intuitive but, in retrospect, somewhat foolish.
Aircraft Information
The aircraft was a 1957 Piper PA-22-150 Caribbean (modified) with one Lycoming O-320-B2B piston engine. It was fitted with an optional reserve fuel tank (8 US gallons) under the rear seat. The pilot, aged 67, held a Private Pilot's Licence with 1,300 hours total (200 on type), but only 0.5 hours in the last 90 days and 0.1 in the last 28 days.