What happened
On 3 February 1999, a Cessna F150H, registration G-AWPP, was performing a private flight from Cranfield to Le Touquet and back. After an uneventful outbound leg, the aircraft departed Le Touquet at 1603 hours, flying at 2,400 feet. While on final approach to Runway 22 at Cranfield, the engine ceased operation without warning. At the time of the failure, the pilot had the carburettor heat engaged and was flying in darkness.
Upon the engine failure, the pilot checked the fuel levels and discovered the right tank was empty, while the left tank contained only one quarter of its capacity. Realising the aircraft could not reach the runway at 700 feet, the pilot declared a MAYDAY and prepared for a forced landing. The pilot located a field and executed the landing, but the aircraft bounced during the process. On the second impact, the nosewheel sank into the soft earth, causing the aircraft to invert. There were no injuries to the two occupants, who evacuated the aircraft without assistance.
The investigation
The investigation examined the fuel levels and the aircraft's maintenance history. Although the pilot's flight plan estimated a fuel endurance of 4 hours 30 minutes, the total time airborne since refuelling was 3 hours 40 minutes. Post-accident inspections of the tanks revealed only a trace of fuel in the right tank and 1.5 litres in the left. While the aircraft had been inverted for several hours, which could have allowed fuel to leak through the filler caps, no fuel staining was observed on the ground.
Investigators also looked into a recent maintenance finding. During a 50-hour check conducted one week prior, the ignition switch had been identified as defective because the magnetos remained live even when the switch was turned off. The aircraft had been operated in this state while awaiting a replacement part. However, laboratory testing of the switch by the AAIB determined that the component was actually serviceable.
Findings
- The engine failure was caused by fuel exhaustion in the right tank.
- The pilot's calculations and fuel gauges incorrectly suggested that at least 30 minutes of fuel remained.
- The aircraft sustained substantial damage during the forced landing.