Narrative
On 28 June 2000 at approximately 1230 hours UTC, a Reims Cessna F152, registration G-BXRN, departed Exeter Airport for a training flight with an instructor and a student on board. The purpose of the flight was to conduct stalling and spinning exercises. During the return leg to Exeter, about 1 mile east of Tiverton, the engine failed and could not be restarted. The instructor transmitted a Mayday call and selected squawk 7700 on the ATC transponder while identifying a suitable field for a forced landing. At approximately 100 feet above ground level, the instructor realised that the chosen field, as well as the surrounding ones, contained standing cereal crop. The aircraft was landed at low speed, but the nosewheel dug into the crop, causing the aircraft to invert.
Both pilots vacated the aircraft without difficulty and reported no injuries. The aircraft sustained severe damage, subsequently assessed as beyond economic repair.
Examination
The aircraft was recovered to its maintenance organisation for examination to determine the cause of the engine failure. Upon removal of the air filter and carburettor heat boxes, a crumpled piece of paper was found lodged in the throat of the carburettor, blocking approximately half of the area. The paper appeared to be about half of a sheet of A4 paper and bore no identifying features except for some red ballpoint pen marks.
Possible Sources of the Paper
The source of the piece of paper remains unknown. The maintenance organisation had recently completed a 50-hour check on the aircraft, but this would not normally, and did not in this case, require removal of any induction system components. The last scheduled maintenance that could have necessitated such work was the aircraft's annual inspection, carried out approximately 50 flying hours before the failure by a different maintenance organisation. Another possibility is that the paper had been lodged in a spare carburettor heat hose that was later used to replace an in-service defective part, although there were no indications that such work had been done recently. The paper would seem to have remained lodged for some time before being drawn into the carburettor. No other reasons for the sudden stoppage were found.