Incident Details
On 5 August 2003, at approximately 1200 UTC, a Socata TB10 Tobago (registration G-BNIJ) suffered a loss of engine power shortly after takeoff from Runway 05 at Sandtoft Airfield, Doncaster, Yorkshire. The aircraft was on a private flight, the second leg of a planned trip from Kemble to Skegness. The pilot, a 72-year-old Private Pilot Licence holder with 1,223 total flying hours (797 on type), and his wife, also a PPL holder who had flown the previous leg, were the only occupants. Neither was injured, though the aircraft sustained substantial damage.
Sequence of Events
Approximately one hour after landing at Sandtoft from an uneventful flight from Kemble, the aircraft was prepared for the onward journey. One litre of oil was added, and after an uneventful engine start, the pre-takeoff checks were completed normally. The pilot backtracked down the runway, performed power checks including carburettor heat and magneto checks, and selected 10 degrees of flap for takeoff. Full power was applied, yielding 2,500 RPM, and the takeoff roll was normal. Upon liftoff, the pilot began a climb at 80 kt. The engine sounded normal until, at approximately 100 feet and 86 kt, it suffered about a 90% power reduction. The aircraft was then passing over a trading estate at the upwind end of the airfield.
The pilot's wife confirmed that the mixture, throttle, propeller, and carburettor heat controls were in their correct positions. The pilot checked the magneto switch and changed fuel tanks in an attempt to restore power. As the aircraft approached stall speed, a forced landing was executed into a field about 800 metres beyond the runway end, to the right of the trading estate. The aircraft touched down heavily and struck a wire fence, which brought it rapidly to rest. The wings, landing gear, nose, engine, and propeller sustained severe damage.
Post-accident Examination
The pilot could offer no explanation for the power loss but believed carburettor icing was unlikely given the temperature of 25°C and relative humidity of 43%. However, according to the CAA's icing probability chart, those conditions place the engine within the 'Serious icing at descent power' envelope, close to 'Moderate icing at cruise power/Serious icing at descent power', but well outside 'Serious icing at any power'. The pilot also suggested a fuel vapour lock but noted it was 'not that hot outside'. An engineer who examined the aircraft found no obvious issues with the throttle linkage or engine controls.
In telephone inquiries, the engineer reported that the right fuel tank (selected at touchdown) had split in impact and was empty. The carburettor had been torn from the engine but remained connected to the fuel feed pipe, which appeared intact. Operating the electric fuel pump produced no pressure. After disconnecting the fuel line from the carburettor and switching to the left tank (intact and containing fuel), the pump again failed to establish flow despite fuel presence and intact pipework. The carburettor contained some fuel but was not full. The fuel had the odour of 100LL, not Mogas.
Investigation
To date, the reason for the power reduction has not been determined with certainty. Should further evidence emerge during repair or dismantling, it will be reported in a subsequent AAIB publication.