What happened
On 18 July 2015, a Spitfire Mk 2 $\text{6}$ (an 80% scale replica), registration G-CENI, was conducting a private flight from Peterborough Connington back to Sibson Airport. During the approach to the downwind circuit, the pilot attempted to deploy the landing gear. While the cockpit indicator suggested the left gear was down, the mechanical indicator on the wing confirmed it remained retracted.
After several attempts to cycle the gear and even performing a go-around, the pilot noticed the left gear remained in the up position. The pilot subsequently attempted to use the emergency gear release system by pulling the release cable, but the left leg failed to deploy. Following further attempts to rectify the situation and managing rising engine oil temperatures, the pilot decided to perform an emergency landing at Sibson. The aircraft touched down on the grass runway with the left gear retracted, resulting in a ground-slide of approximately 10 metres. There were no injuries to the pilot, though the aircraft sustained damage to the propeller, engine, firewall, flaps, and fuselage underside.
The investigation
The investigation focused on why the landing gear failed to extend both through normal electrical operation and the emergency gravity-drop system. Investigators found that the left landing gear down microswitch had become stuck, preventing the electrical circuit from completing to activate the extension motors.
Furthermore, the investigation established that the emergency release system was ineffective because of residual tension in the gear leg. This tension was caused by a slightly bent gear leg, which had forced the wheel against the underside of the wing skin. This physical obstruction prevented the gear from dropping via gravity and spring assistance even after the locking pin was removed.