What happened
On 12 July 2018, a Beagle B121 Series 2 Pup, registration G-TSKY, was performing a private flight from Kemble Airfield to Bembridge Airfield. During the pre-takeoff phase at Bembridge, the pilot noted an unusual noise and, following advice from a colleague, performed a restart. After confirming all checks were satisfactory, the aircraft commenced its takeoff roll from Runway 30.
As the aircraft climbed through 300 feet, the pilot retracted the flaps. Shortly thereafter, the engine power decreased rapidly without any accompanying noise or vibration. With insufficient altitude to attempt a turn back to the airfield, the pilot focused on finding a suitable landing area. The aircraft descended into nearby marshland, striking the ground with a high vertical descent rate and a right wing low. Both the pilot and the passenger sustained serious injuries.
The investigation
The AAIB investigation focused on the cause of the engine power loss and the circumstances of the impact. Examination of the Lycoming O-320 engine revealed no mechanical defects, and the magnetos, spark plugs, and fuel pumps were all found to be operating normally. However, investigators noted that two nuts connecting the fuel pipe to the carburettor were not wire-locked, contrary to maintenance manual requirements.
Fuel system tests confirmed that fuel flow from the wing tanks was within specification, and fuel samples showed no contamination. While the fuel tank vent was found to be clear, the investigation considered whether a temporary blockage could have caused a vacuum in the tanks. Additionally, flight testing of a similar aircraft demonstrated that flying at speeds too close to the stall speed (approximately 55 KIAS with 10° flaps) leaves insufficient energy to effectively flare the aircraft, which likely contributed to the severity of the impact.
Findings
- The most likely cause of the power loss was fuel starvation, though the specific mechanism remains undetermined.
- The aircraft struck the ground with a high rate of descent, suggesting the pilot may not have maintained the recommended glide speed of 65 KIAS.
- The pilot's decision to land straight ahead was appropriate given the low altitude and lack of maneuvering room.
- The manual activation of the portable personal location beacon (PLB) was not possible due to the injuries sustained by the occupants.
- The lack of wire-locking on certain fuel pipe components was identified as a maintenance discrepancy.