Accident Overview
On 29 June 2006 at 1237 hours, a Piper PA-23-250 Aztec, registration G-BBEY, crashed near Thirkleby Hall, Thirkleby, North Yorkshire. The private flight was the first flight after maintenance that included work on the left engine fuel system. The aircraft was destroyed, and the sole pilot received fatal injuries.
Flight History
The pilot arrived at Bagby Airfield that morning. After refuelling the left outer tank, he sought help from the maintenance company owner to troubleshoot non-working navigation and strobe lights, which were rectified. The pilot started both engines, taxied to Runway 24, and performed power checks; witnesses noted no propeller exercising. He then called the maintenance owner for a radio check without reporting issues.
During takeoff from Runway 24, witnesses observed rough engine sounds and smoke—black from the left engine, grey from the right. The takeoff ground roll was excessive. The aircraft became airborne about three-quarters along the 710-metre grass runway, and the landing gear was raised. An engineer in the tower radioed a warning about a possible problem. The pilot reported that the aircraft was not climbing properly and flew a left circuit for Runway 24.
On final approach, the pilot confirmed landing gear down. The aircraft landed heavily, bounced multiple times, and then initiated a go-around. Witnesses saw dense black smoke from the left engine and less dense smoke from the right. The aircraft climbed slowly at low speed, banked steeply left, and turned onto a reciprocal heading. At about 100 feet, the left wing dropped, the aircraft pitched down, struck the ground, and burst into flames.
Wreckage Examination
The accident site was 0.8 km south of Bagby airfield. Impact marks indicated the aircraft struck the ground in a near-vertical nose-down attitude, spinning left, on a west-south-westerly heading. Both wings detached, and a fuel-fed fire consumed most of the structure. Propeller ground marks showed the right engine at high power and the left at medium power. The flying control systems were intact, with no disconnections. The landing gear was near but not fully retracted.
Engineering Findings
Both engines had reasonable mechanical condition but showed signs of long inactivity. The left engine fuel injector nozzle was blocked; the other nozzles functioned at 55% to 91% of maximum flow. The blockage was caused by ferrous corrosion and nickel deposits. Fuel injector distribution valves and pipes on both engines performed satisfactorily. The propellers showed no pre-impact faults. The post-impact fire prevented determination of bird strike, pre-impact fire, or loose panels.
Probable Cause
A reduction of power affecting the left engine occurred, probably due to blockage of a fuel injector nozzle.