What happened
On 29 June 2017, a Cessna 210A, registration ZS-SOK, was conducting a private flight from Eagles Creek to Pilanesberg International Airport. The flight was intended to facilitate customs clearance for a subsequent journey to Zimbabwe. During the approach to Pilanesberg, the pilot attempted to extend the landing gear but observed that the green indicator light on the instrument panel failed to illuminate.
Due to this uncertainty regarding the gear status, the pilot elected to divert to Rand Airport, where the aircraft's maintenance base is located. Upon arrival at Rand, the pilot performed a circuit and requested that the control tower visually confirm the gear position. The tower reported that the gear appeared to be extended. The pilot proceeded to land on runway 29.
During the landing roll, approximately 400 meters from the start of the runway, the left main landing gear collapsed. The aircraft veered left, skidding on its left wingtip and horizontal stabilizer before coming to rest near the intersection of runway 29 and runway 35. The two occupants of the aircraft sustained no injuries.
The investigation
SACAA AIID investigators examined the wreckage and the mechanical components of the aircraft. Metallurgical analysis conducted by the NTSB Material Laboratory on the recovered left hand saddle assembly revealed that the component had suffered an overstress fracture. This failure occurred under multiple loading conditions.
Records indicated that the saddle assembly was a relatively new component, having been installed approximately four years prior with only 71.7 airframe hours and 67 landings since installation. The investigation also reviewed maintenance logs, noting that the aircraft had undergone a 100-hour inspection earlier in 2017 and that the specific component was not yet due for its next mandatory airworthiness directive inspection.
Findings
- The primary cause of the gear collapse was the failure of the left hand saddle assembly due to multiple fractures caused by overstress under various loads.
- A contributing factor was that the aircraft landed with the left main landing gear not being fully extended or locked, which likely contributed to the structural failure of the assembly.
- The aircraft sustained minor damage to the left wingtip, the left horizontal stabilizer, and the left saddle assembly.