What happened
On 11 May 2013, a Beech 58, registration ZS-KLL, was conducting a local private flight departing from and returning to Wonderboom Airport (FAWB). The aircraft was carrying a pilot and three passengers. During the landing sequence on Runway 06, the pilot experienced the main undercarriage making contact with the runway, immediately followed by the nose gear striking the ground. The impact caused the propellers to strike the runway surface and the nose wheel to sink into the asphalt before the aircraft came to a halt. There were no injuries to the four occupants, though the aircraft sustained damage to the propellers, nose cone, and undercarriage.
The investigation
An investigation by the SACAA AIID examined the mechanical state of the landing gear assembly. While the pilot could not confirm seeing the three green landing gear indicators, a physical inspection of the wreckage revealed that the nose gear was not extended. Maintenance records indicated that the aircraft had been properly maintained and was up to date with mandatory periodic inspections. Meteorological data confirmed that weather conditions were clear with good visibility, ruling out environmental factors as a cause.
Upon lifting the aircraft, investigators found that the nose gear doors were in the closed position and showed extensive chafing. The investigation focused on the mechanism's failure to deploy. It was discovered that the nose gear extension bellcrank on the actuator was cracked and bent, and the aft nose gear extension rod had broken at the rod end. To facilitate the inspection, the nose gear doors had to be manually pried open.
Findings
- The primary cause of the accident was that the nose gear doors jammed, which prevented the nose gear from extending.
- The nose gear assembly was compromised by a broken aft retract rod and a cracked extension bellcrank.
- The main landing gear was only partially extended during touchdown, leading to a gradual collapse of the gear under the aircraft's weight.
- The pilot's inability to confirm the gear-down indication contributed to the sequence of events.
- The aircraft's maintenance history was found to be in compliance with all regulatory requirements.