What happened
On 17 September 2006, a Tecnam P2OF2-EA Sierra, registration G-TESI, departed from Hinton-in-the-Hedges for a private flight. The aircraft took off from a recently cut grass airstrip that featured significant undulations. While the initial takeoff roll appeared normal, the aircraft banked steeply to the left shortly after lifting off at the first rise of the runway. Following this bank, the aircraft ceased to accelerate despite the throttle being at full power. Realising a climb was not possible, the pilot initiated an immediate landing. The aircraft touched down heavily approximately 25 metres to the left of the runway strip in a hollow area. Upon impact, the nose landing gear dug into the soft ground and collapsed. There were no injuries to the pilot or the passenger, though the aircraft sustained damage to the propeller, engine frame, fuselage, nosewheel, and left wing.
The investigation
Investigators examined the aircraft and the circumstances surrounding the fuel system. During the recovery of the aircraft from the site using a digger, it was noted that the aircraft hung noticeably with the left wing low. A subsequent inspection of the fuel tanks revealed that while the left tank contained approximately 40 litres of fuel, the right tank was empty. It was discovered that both fuel taps had been left in the 'ON' position, and because the aircraft had been parked on a slight side-slope, the fuel from the right tank had gravity-fed into the left tank. This created a significant lateral imbalance. Furthermore, an examination of the propeller suggested it may not have been rotating at the moment of impact, leading investigators to consider whether the engine had suffered a power loss during the takeoff roll.
Findings
- The aircraft was operated with a significant lateral fuel imbalance caused by the gravity transfer of fuel from the right tank to the left tank.
- Both fuel taps were left in the 'ON' position while the aircraft was parked on a slope.
- The fuel imbalance likely caused the steep bank and subsequent loss of climb performance during takeoff.
- The engine may have experienced a loss of power during the takeoff phase, though the pilot did not initially report a change in engine note.