Accident Details
On 9 October 2005 at 1335 UTC, a Cessna 152 (registration G-BGIB) made a forced landing in a field north of Arlington Reservoir, East Sussex. The aircraft was manufactured in 1979 and powered by a single Lycoming O-235-L2C piston engine. The flight was a private training exercise, with a student pilot under the supervision of an instructor. Both occupants were uninjured. The aircraft sustained damage to the nose landing gear, left wing tip, propeller, and underside of the engine cowling.
Flight Sequence
The flight was planned as a practice 'forced landing without power' exercise. After a normal start, the engine stopped twice before the instructor intervened and restarted it. The aircraft climbed to 3,000 ft and a series of en-route checks and practice glide descents were performed. During a subsequent descent from 2,000 ft, carburettor heat was selected to 'HOT' and power was reduced to idle. The instructor increased power twice to warm the engine, but carburettor heat remained selected. At 800 ft, the student advanced the throttle with no response. The instructor took control, exercised the throttle without effect, then shut down the engine and prepared for a forced landing.
Landing and Damage
The aircraft touched down in a field sloping downhill. After a ground roll of approximately 200 m, the instructor determined that the aircraft would not stop before a wooded area. Heavy braking was applied, causing the nose landing gear to collapse and the aircraft to tip onto its nose. Both occupants exited via the doors.
Examination and Findings
Examination at the accident site by the club's Chief Flying Instructor and a maintenance engineer revealed a split in the flexible hose that supplies hot air to the carburettor air box. The split extended approximately two-thirds around the circumference. The hose was a double-ply 'Sceet' type rather than the specified single-ply 'Scat' hose. The maintenance organisation reported that the hose was fully connected to the metal tube stub on the carburettor air box and held by a metal clamp; they considered the split had developed due to chafing around the clamp.
Weather and Icing Considerations
Meteorological observations from nearby stations at 1300 UTC showed temperatures and dew points consistent with conditions conducive to carburettor icing, especially at descent power. The instructor noted no rough running and the engine performed within limits before the power loss. The presence of the split in the hot air hose could have allowed colder air from the engine bay into the carburettor, making carburettor ice build-up more likely despite the selection of hot air.