What happened
On 10 January 2011, a Nipper T.66 RA45 Series 3, registration G-CBCK, was performing a private flight from Abbots Hill Farm Strip in Hertfordshire. During the takeoff roll, the engine reached full power, but shortly after the aircraft became airborne, the engine lost power. To avoid obstacles, the pilot closed the throttle and executed a right turn to land on a down-sloting, uneven patch of ground. The aircraft touched down at a groundspeed of approximately 40 kt. Upon landing, the left wingtip struck the ground, causing the left and nose landing gear to collapse. The aircraft subsequently tipped forward onto its nose and right landing gear. The pilot, who was wearing a full harness, sustained no injuries.
The investigation
The investigation examined the fuel system and the pilot's pre-flight procedures. The aircraft's fuel system consisted of two independent tanks with no cross-feed capability; the pilot manually selected which tank supplied the engine. The main tank featured a fuel gauge, while the auxiliary tank did not. During the pre-flight inspection on the morning of the accident, the pilot found the filler caps difficult to remove due to the cold weather. Based on a previous flight where the auxiliary tank had been empty, the pilot assumed the auxiliary tank was also empty and did not perform a visual check of its contents.
Post-accident inspections revealed that the main fuel tank was empty, whereas the auxiliary tank contained two gallons of fuel. The pilot noted that the main tank gauge had previously indicated approximately three gallons remained. The investigation looked into whether fuel had migrated between tanks through a faulty selector switch.
Findings
- The engine lost power because the main fuel tank, which was selected for takeoff, had run dry.
- The pilot did not visually verify the fuel levels in both tanks during the pre-flight inspection.
- Fuel had transferred from the main tank to the auxiliary tank via a defective fuel tank selector switch.
- The pilot's decision not to check the auxiliary tank was based on the assumption that it was empty, following a previous flight where the engine had been run on the ground until the auxiliary tank was depleted.