Background
The Varsity aircraft, originally a twin-engine training aircraft used by the Royal Air Force until 1974, was sold into private ownership and maintained by an aircraft preservation group. It carried the military designation 'WJ897' on the fuselage and wings and was registered as G-BDFT. The aircraft held a Permit to Fly restricted to display and demonstration flying and practice for such displays.
Flight
Thirteen society members boarded the aircraft earlier that morning at RAF Syerston in Nottinghamshire for a short flight to East Midlands Airport (EMA). After an uneventful flight, the aircraft landed and was refueled with 436 imperial gallons of aviation gasoline (Avgas 100 LL), bringing total fuel to 510 imp gal. The intended destination was Liverpool Airport (LPL) for an air display that afternoon. A Cessna 180 was arranged to take aerial photographs of the Varsity during the flight to Liverpool, with a rendezvous planned at 3,000 feet amsl near Blithfield Reservoir, about 20 miles west of East Midlands Airport.
The Varsity engines were normally started using ground electrical supply. On this occasion, the left engine was reluctant to start; after initially firing, it faltered and stopped, emitting smoke from the exhaust. To avoid exhausting the batteries, the right engine was started first. The left engine was then motored over before another successful start attempt. Passengers were told that the left engine had been over-primed during the first start attempt.
The Varsity took off at 09:32. The approach controller at East Midlands Airport provided bearing and range information to help the Varsity pilot locate the Cessna 180. At 09:47, both aircraft switched to a discrete radio frequency. The Varsity then flew in formation on the right side of the Cessna in wide orbits around Blithfield Reservoir. During this time, the left engine emitted occasional puffs of smoke accompanied by loud bangs.
When the photographer requested that the Varsity climb slightly above the Cessna and lower its undercarriage, the Varsity pilot reported trouble with the right engine. The Cessna pilot noted that the left engine seemed to be the issue, as he saw puffs of smoke indicative of a rich mixture. When the Varsity pilot suggested engine icing, the Cessna pilot noted his intake temperature indicated no risk of intake icing. The Varsity undercarriage was lowered briefly before being retracted, with the pilot stating he 'could not accept the drag and might have to abort the photography.' Towards the end of the photographic session, the right engine also began to backfire.
Accident
At 10:05, the Varsity pilot contacted East Midlands Airport on the approach frequency, requesting a direct return due to engine problems and a possible emergency declaration. The approach controller provided a course to steer and asked if the Varsity could maintain height. The pilot replied, 'at the present we are able to but it's with some difficulty.' The Varsity steadily lost height, and at 10:07, the pilot reported that the left engine had stopped. Thirty seconds later, the co-pilot radioed, 'we're going to have to put it down in the nearest field, we're down to 400 feet and losing power on both engines so we are going into the...' The undercarriage was lowered, and at very low height, the left wing dropped, the aircraft rolled over, and the nose dropped, resulting in an inverted crash. Just before impact, the left mainplane severed 11,000-volt electricity supply wires. The aircraft broke up on impact, and the rear fuselage with the empennage fell into a drainage ditch about 10 feet deep. Three survivors, seated in rearward-facing seats in this part of the fuselage, were able to escape; one had a broken leg and received severe burns when a wire fence prevented leaving the accident area.
Probable Cause
The accident was caused by a loss of control when the aircraft stalled at low altitude while the pilot was attempting a forced landing following a progressive loss of power on both engines. The loss of power on the left engine resulted from an excessive rich fuel/air mixture caused by a split diaphragm within the engine-driven fuel pump. It was not possible to determine the cause of the loss of power on the right engine, but it possibly resulted from ignition failure due to ignition coil breakdown at high engine boost settings.