What happened
On 22 August 2023, a Spitfire Mk 26B, registration G-CLHJ, was conducting a flight test programme near Enstone, Oxfordshire, as part of the process to obtain a Permit to Fly. The flight was intended to evaluate the effects of newly repositioned stall strips on the aircraft's leading edges.
After taking off from Enstone Airfield, the pilot climbed to an altitude between 3,000 and 4,000 feet. Witnesses observed the aircraft performing a series of stall manoeuvres. While the first two manoeuvres resulted in successful recoveries, the aircraft entered a clockwise spin or rotation following the third stall. The aircraft subsequently struck an open field, where it caught fire. The pilot sustained one fatal injury.
The investigation
The AAIB examined the wreckage and analyzed CCTV footage from the airfield. Although the cockpit and nose were heavily damaged by fire, investigators were able to assess the aircraft's structural integrity and control systems.
Key elements of the investigation included:
- Control Systems: Investigators checked the mechanical push-pull rods and rudder cables. While no malfunction was found, the fire prevented the exclusion of a potential control restriction caused by a foreign object.
- Fin and Rudder: Precision measurements revealed that the fin and rudder were misaligned by 4.4° to the left of the aircraft's centre line. The construction team had noted this during assembly but believed it was a deliberate design feature.
- Stall Strips: The position of the stall strips on the right wing was confirmed to be consistent with the pilot's recent adjustments.
- Pilot Health: The pilot had a history of significant heart disease. While the pathologist found no definitive evidence of a recent cardiac event, the possibility of sudden incapacitation could not be dismissed.
Findings
- The aircraft was constructed with a misaligned fin and rudder, which created a pro-spin condition by making a wing drop more likely during a stall.
- The pilot had successfully completed two previous stalls during the same flight, suggesting he was familiar with the aircraft's handling.
- The exact reason the pilot failed to recover from the third stall could not be determined; however, investigators considered startle response, pilot incapacitation, or a control restriction as possible factors.
- The aircraft's construction involved significant rework of kit parts, and the misalignment was mistakenly assumed to be a standard feature of the design.