Accident Details
On 10 September 2000 at 1316 UTC, a DH82A Tiger Moth, registration G-ANMV, operated by a public transport pleasure flight service, was conducting a flight near Aston, Henley-on-Thames. The aircraft was powered by a single de Havilland Gipsy Major 1F piston engine. The pilot, holding an Airline Transport Pilot's Licence with an Instructor Rating, was aged 38 and had 7,200 total flying hours, including 56 hours on type. One passenger was on board. The flight had been planned for 30 minutes, and 20 minutes had elapsed when the passenger requested aerobatics.
Flight Sequence
The pilot had previously performed basic aerobatic manoeuvres that day, including loops, barrel rolls, and wing-overs. The final manoeuvre began at 2,000 feet. The aircraft was pitched nose-up to 80 degrees from level flight at 100 knots. At low airspeed with the engine at full power, the aircraft was yawed to the right using full right rudder. During the yaw, the throttle was smoothly retarded. The aircraft then entered a steep dive, and the engine 'coughed' as it had on all previous flights. However, unlike previous occasions, the engine did not restart. The dive was continued to keep the propeller windmilling, but it stopped turning after about 3 seconds. As the Tiger Moth lacks a starter, a forced landing became inevitable.
Forced Landing
The aircraft was leveled off at approximately 1,000 feet and slowed to the best glide speed of 55 knots. The pilot selected a field and transmitted a MAYDAY call on the Wycombe Air Park frequency, providing the aircraft position. A series of steep S-turns were executed to stay at the eastern edge of the chosen field. Alignment with the into-wind axis of the field was achieved at about 70 feet. The aircraft was flared with wings level, but on touchdown the main landing gear collapsed. The aircraft slid along the ground and then pitched over at low speed, coming to a halt inverted. There was no indication of fuel leaking. The pilot instructed the passenger to remain harnessed and not move. The pilot released his own harness and checked the passenger, who had suffered a cut above the left eye and was experiencing back pain but had full limb use. Due to a risk of fire, the passenger was supported and released from his harness with help from a member of the public, then moved to a safe distance. The accident was attended by air ambulance and police helicopters along with other emergency services.
Post-Accident Examination
The pilot reported that he had successfully flown the same manoeuvre at least ten times since the engine's overhaul, including on the three flights immediately preceding the accident, with the propeller continuing to windmill each time. The engine had been installed in February 2000 after overhaul and had operated for 67 hours with no recorded defects. The Tiger Moth and Gipsy Major engine combination does not have an inverted fuel system, and it is possible during aerobatic manoeuvres to starve the engine of fuel, causing it to stop. Such a condition combined with low airspeed can stop the propeller from turning, and with a recently overhauled engine with relatively high compressions, it may be impossible to restart using airflow. After recovery, fuel remained in the tank, fuel filters were clear, carburettor jets were clear, magnetos and spark plugs were serviceable, and examination of the engine revealed no defects that would have caused the engine to stop.