What happened
On 26 August 2007, a Pegasus Quantum 15 microlight, registration G-BZJF, was performing a series of maneuvers near Knotting Wood, Northamptonshire. The flight, which was a private operation, had departed from Sackville Farm earlier that evening. During a turn, the aircraft entered a rapid, uncontrolled rotation known as a tumble. This sequence caused the wing and the trike unit to separate mid-air. The pilot was ejected from the trike during the breakup. Both the pilot and the passenger sustained two fatal injuries upon impact with the ground.
The investigation
Investigators examined the wreckage to determine the sequence of the structural failure. The examination of the trike's 'A' frame revealed that the basebar had failed in bending after striking the front strut. This impact was powerful enough to bend the strut tubing itself. Evidence from the wing showed that the propeller had struck the rear of the wing keel tube while the engine was still running. The wreckage distribution indicated that the aircraft had been subjected to violent, alternating upward and downward loads, which are characteristic of a tumble. While the engine and airframe were found to be in good working order with no mechanical failures identified, the investigation looked into whether the pilot had encountered severe turbulence or wake vortex.
Findings
- The aircraft experienced a structural breakup caused by extreme aerodynamic loads far exceeding its design limits.
- The failure sequence likely began with the 'A' frame basebar striking the front strut, which rendered the aircraft uncontrollable.
- The aircraft entered a tumble, a high-velocity pitch rotation that is notoriously difficult to recover from.
- There was no evidence of pre-existing mechanical or structural defects that would have initiated the breakup.
- The pilot may have been subjected to significant wake turbulence or was attempting a maneuver that induced the tumble.