Nosewheel shimmy causes nosewheel collapse in Lancair 320

Casualties unknown • Cranfield Aerodrome, Bedfordshire, GB

A newly completed kit aircraft experienced a violent nosewheel shimmy during takeoff at Cranfield, leading to a nosewheel collapse and engine damage.

What happened

On 28 May 1999, a Lancair 320, registration G-FOPP, was performing a private flight at Cranfield, Bedfordshire. The aircraft, which had been constructed from a kit purchased in 1992 and completed earlier that year, was being operated by an experienced test pilot for its inaugural flight.

During the takeoff roll, a right-hand wind effectively balanced the torque reaction, requiring minimal rudder input. As the aircraft reached 65 kt, the pilot began the rotation process. However, immediately upon the nosewheel losing contact with the runway, the aircraft experienced a violent shimme. This was followed by a sudden downward pitch of the nose. In an attempt to maintain control, the pilot applied full aft stick and closed the throttle, but the aircraft settled onto its nose and slid along the runway until it came to a stop. The incident resulted in no injuries to the pilot, though the aircraft sustained damage to the propeller, engine, cowling, and engine supports, and the nosewheel collapsed.

The investigation

The investigation focused on the mechanical cause of the sudden instability during rotation. Investigators examined the oleo-pneumatic nose strut, which contains the shimmy damper. It was determined that the strut installed on G-FOPP was an obsolete version that had been phased out due to known shimmy issues.

While the part number (GM 14) was identical to the newer, improved version, the two components were produced by different manufacturers and possessed distinct external appearances. The faulty strut was identified as being manufactured by 'AROTEK' of Washington State, USA, whereas the updated replacement version is produced by 'ESCO'. The kit manufacturer confirmed that their records indicate no other customers are currently in possession of this discontinued 'AROTEK' standard strut.

Probable cause

The nosewheel collapse was caused by a violent shimmy resulting from the installation of an obsolete, discontinued type of nosewheel strut that was prone to instability.

Frequently asked questions

What happened in the 1999-05-28 LANCAIR 320 accident near Cranfield Aerodrome, Bedfordshire, GB?

A newly completed kit aircraft experienced a violent nosewheel shimmy during takeoff at Cranfield, leading to a nosewheel collapse and engine damage.

What aircraft was involved and where did it happen?

The accident on 1999-05-28 involved a LANCAIR 320, registration G-FOPP, at Cranfield Aerodrome, Bedfordshire, GB.

What was the probable cause of the accident?

The nosewheel collapse was caused by a violent shimmy resulting from the installation of an obsolete, discontinued type of nosewheel strut that was prone to instability.

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