What happened
On 14 August 2016, during the Herne Bay Air Show in Kent, a Druine D.31 Turbulent, registration G-ARNZ, experienced a sudden loss of engine power. The incident occurred during a specific segment of the flight display involving the bursting of balloons. After successfully striking a balloon with the propeller, the pilot noted a significant reduction in engine power while on the downwind leg of the flight pattern.
Unable to reach land, the pilot attempted to ditch the aircraft in the shallow intertidal zone near the beach to avoid populated areas. The pilot intended to stall the aircraft into the water tail-first to maintain an upright position. However, the main wheels contacted the water first, causing the aircraft to pitch forward and flip onto its back. The pilot, who sustained one minor injury, became trapped in the inverted cockpit because his automatically inflated lifejacket created too much bulk to allow for escape. Bystanders on the beach reached the aircraft and managed to right the plane, allowing the pilot to be rescued.
The investigation
Investigators examined the engine of the G-ARNZ and discovered a 50 mm piece of orange balloon material lodged within the carburettor. This fragment had restricted the airflow necessary for engine operation. The investigation also reviewed the pilot's equipment, noting that the lifejacket used was designed for maritime use and featured an automatic inflation mechanism triggered by moisture. This inflation, while functional, contributed to the pilot's inability to extricate himself from the submerged cockpit.
Findings
- A fragment of a balloon became lodged in the carburettor air path, causing the loss of engine power.
- The aircraft's landing technique resulted in an inverted position upon contact with the water.
- The automatic inflation of the pilot's lifejacket hindered his ability to escape the inverted cockpit.