What happened
On 31 May 2010, a Bellanca 7GCBC Citabria, registration G-HUNI, was performing a private flight at Henstridge Airfield in Somerset. During the landing phase on Runway 07, the aircraft experienced a sudden mechanical failure. As the aircraft touched down, the right main landing gear leg detached from the airframe. This failure caused the aircraft to veer toward the right side of the runway, eventually coming to a halt beside the runway, facing the opposite direction of the approach. Despite the impact, there were no injuries to the pilot or the single passenger on board, and both occupants were able to exit the aircraft without assistance.
The damage sustained by the aircraft included the landing gear, the propeller, the right wingtip, and the underside of the fuselage. At the time of the incident, weather conditions were reported as good, with a light wind from 060° at 5 knots, and the pilot had noted that the approach and touchdown appeared normal.
The investigation
The AAIB examined the detached portion of the steel landing gear leg. Laboratory analysis of the fracture surfaces revealed that a pre-existing crack, measuring approximately 15 mm in depth, had been present in the gear leg. The investigation established that this crack had propagated through the metal, eventually leading to the complete failure and detachment of the leg during the landing sequence. Furthermore, the inspection of the fracture surfaces showed significant corrosion, suggesting that the crack had been developing for a considerable period before the accident occurred.