What happened
On 7 April 2018, a Piper PA-18-150 Super Cub, registration G-RWCA, was conducting a private cross-country flight from Crowfield when the pilot noticed oil dripping into the cockpit. While the oil pressure initially remained stable, it eventually dropped to 60 psi. Due to the ongoing leak, the pilot elected to perform a precautionary landing at the nearby Beccles Airfield.
Upon communicating with the airfield radio operator, the pilot was informed that the landing should be restricted to the concrete portion of the runway. This presented a challenge, as the pilot had no prior experience landing a tailwheel aircraft on a hard surface. The approach was flown high and fast with full flaps, resulting in a float and a subsequent bounce before the aircraft settled into a three-point landing.
As the aircraft decelerated toward the end of the concrete strip, the pilot applied full left rudder to correct a rightward yaw but did not utilize the wheel brakes. The aircraft drifted off the concrete and onto the adjacent grass. The transition to the soft ground caused the aircraft to ground loop and eventually nose over, coming to rest in an inverted position. There were no injuries to the pilot.
The investigation
The AAIB examined the sequence of events leading to the loss of control on the ground. The investigation focused on the pilot's landing technique, the surface conditions of the runway at Beccles, and the impact of the aircraft's transition from concrete to grass. The investigation also noted the mechanical state of the engine, which had suffered a shock-load to the propeller during the impact.
Findings
- The pilot was managing an active engine oil leak and declining oil pressure.
- The pilot was operating a tailwheel aircraft on a hard surface for the first time.
- The aircraft's main wheels left the concrete runway and entered the soft grass area.
- The aircraft's transition from the concrete runway to the soft grass surface caused the nose-over.
- The aircraft sustained damage to the wings, fin, rudder, and windscreen, and the propeller was bent due to engine shock-loading.