What happened
On 7 March 2008, a Beech B200, registration ZS-LFU, was conducting a private flight from Bloemfontein Aerodrome to Cape Town International Aerodrome. The flight, which included the pilot and six passengers, proceeded normally through the approach phase. Upon landing on Runway 19, the pilot confirmed that the landing gear was down and locked via three green cockpit indicators.
While the aircraft was mid-way through its landing roll, the pilot noticed the left side of the aircraft beginning to sink. The left-hand propeller subsequently struck the runway surface. The pilot attempted to maintain directional control and keep the left wing elevated for as long as possible, eventually bringing the aircraft to a halt left of the runway centerline. While there were no injuries to the seven people on board, the aircraft suffered significant damage to the engine, propeller, left wing, and flaps. Minor damage was also noted on the runway asphalt.
The investigation
SACAA AIID investigators examined the wreckage and the aircraft's maintenance history. The investigation confirmed that the aircraft was maintained according to manufacturer specifications, with the most recent phase inspection completed approximately 25 hours prior to the accident. Although a previous maintenance entry noted an intermittent landing gear indicator switch, a new switch had been installed and tested successfully.
Metallurgical analysis of the recovered components focused on the left main landing gear assembly. The examination of the hook down lock mechanism (Part No. 50-810338-5) revealed that the component had failed due to a fatigue fracture. Investigators determined that this fracture had likely progressed over an unspecified period, potentially triggered by a prior overload event.
Findings
- The primary cause of the landing gear collapse was a fatigue fracture within the left main landing gear hook down mechanism.
- There were no cockpit warnings or indications provided to the pilot prior to or during the landing roll to suggest an impending mechanical failure.
- At the time of the accident, there were no active Airworthiness Directives (AD) or Service Bulletins (SB) from the manufacturer, Hawker Beechcraft Corporation, regarding this specific component.
- The aircraft was 25 years old at the time of the incident.