What happened
On 27 May 2006, a Europa aircraft, registration G-PTAG, was performing a private flight returning to Wickenby, near Market Rasen, Lincolnshire. Following a smooth touchdown on Runway 34, the aircraft began its ground roll normally. However, approximately 20 metres after the nosewheel made contact with the runway, the nosewheel began to shimmy violently.
Shortly thereafter, the nosewheel fork assembly detached from the aircraft. Because the nose gear leg on this model is swept forward, its detachment caused the leg to rotate rearwards into an extreme nose-down position. This movement resulted in the propeller striking the tarmac and the underside of the main wheel fairings scraping the runway surface. The aircraft eventually came to a stop 105 metres from the start of the shimmy. The pilot and passenger escaped the incident uninjured, though the aircraft sustained damage to the fuselage, nose gear leg, propeller, and various fairings.
The investigation
Investigators examined the nosewheel fork assembly and the damaged nose gear leg. Metallurgical analysis of the scroll pin, which was intended to secure the fork unit, revealed that the pin had failed in shear due to an overload. The investigation noted that the hole through which the pin was inserted had been drilled inaccurately, meaning it was not perpendicular to the axis of the pivot shaft. This misalignment, combined with burrs present in the hole, likely compromised the pin's structural integrity.
Evidence from runway markings suggested the aircraft struck a small pothole during the ground roll, which caused the gear leg to strike the aircraft structure and fail. The investigation also considered the possibility of a previous heavy landing, as the aircraft had experienced a nosewheel-first landing approximately three years prior, which had required the replacement of the nose gear leg.
Findings
- The primary cause of the incident was the failure of the scroll pin in shear due to an overload.
- The failure was likely exacerbated by a manufacturing defect where the scroll pin hole was off-centre and non-perpendicular to the pivot shaft axis.
- The detachment of the nosewheel fork caused the nose gear leg to rotate rearwards, leading to the propeller strike and subsequent damage to the lower cowl and fairings.
- The aircraft encountered a pothole on the runway, which contributed to the structural failure of the gear leg attachment.