What happened
On 10 August 2000, a Star-Lite SL-1, registration G-BUZH, was undergoing taxi trials at Farley Farm in Hampshire. Following extensive maintenance work that had commenced in late 1999, the pilot intended to perform several ground runs to test the aircraft before arranging a flight with a more experienced pilot.
During the taxi on a grass runway, the aircraft reached a speed that triggered a pitch oscillation after the main wheels struck a bump while the aircraft was in a nose-up attitude. Although the pilot closed the throttle, the downhill gradient of the strip prevented the aircraft from slowing down without braking. A subsequent impact with a small ridge caused the nose landing gear to fail. The aircraft's nose and spinner made contact with the ground, and the aircraft slid and turned left before coming to a halt on a nearby gravel track. The incident resulted in no injuries to the pilot, but caused damage to the propeller, engine mounts, and forward fuselage.
The investigation
Investigators examined the aircraft and the circumstances of the ground movement. It was discovered that the aircraft's airspeed indicator was under-reading by 10 mph at speeds below 50 mph. This meant the actual speed during the initial bump was approximately 35 mph, rather than the 25 mph initially reported. This higher speed was close to the aircraft's flying speed in ground effect, which contributed to the onset of the pitch oscillation and increased the loads on the landing gear.
Further inspection of the nose landing gear revealed several structural concerns. The pilot identified three specific manufacturing features that likely contributed to the failure: a welding gas vent hole in the tubular leg had been plugged with a fastener, a planned strengthening web modification had not been implemented, and the necessary post-welding heat treatment for the components had been omitted.