What happened
On 23 May 2008, a DH82A Tiger Moth, registration G-ANJA, was performing a solo flight near Headcorn Aerodrome. After completing a recent check flight, the pilot initiated an aileron roll, pitching the aircraft up to an angle of between 15 and 20 degrees. As the aircraft passed through the inverted position, the engine stopped abruptly and the propeller ceased rotation.
Following the engine failure, the pilot regained level flight but determined there was insufficient altitude to restart the engine. After evaluating several landing sites, the pilot rejected a field containing tall crops and identified a nearby playing field. Upon noticing children in that field, the pilot redirected the aircraft toward a golf course. Realising the height was insufficient to reach the golf course, the pilot transmitted a 'Mayday' call and chose to stall the aircraft into a preceding field. The landing gear collapsed upon impact, causing significant damage to the wings, engine cowlings, and fuselage structure. The pilot escaped the aircraft without injury.
The investigation
Investigators examined the mechanical operation of the aircraft's fuel system. The DH82A Tiger Moth features a single fuel tank located between the upper wings, which gravity-feeds a conventional carburettor. The investigation established that the engine failure was linked to the aircraft's performance under negative 'g' loads. Specifically, when the aircraft is inverted, the fuel flow from the tank to the carburettor is interrupted, and the fuel remaining in the float chamber moves to the top of the chamber, causing the main jet to draw air instead of fuel.
Findings
- The engine stopped due to fuel starvation caused by negative 'g' forces during the inverted phase of the roll.
- The pilot's decision to stall the aircraft into the field was driven by the presence of children in the previously selected landing site.
- The aircraft sustained substantial damage, including a collapsed undercarriage and broken fuselage longerons.