What happened
On 4 June 2013, a Beechcraft King Air E90, registration V5-SMA, was conducting type conversion training flights between Lanseria International Airport and Rustenburg Aerodrome. The flight crew, consisting of a flight instructor and two student pilots, had completed an initial successful training session earlier in the day.
During the second training session, the aircraft returned to Rustenburg Aerodrome for a series of touch-and-go landings. While performing the landing sequence on Runway 34, the crew heard audible impacts coming from the right side and then the nose section of the aircraft. The nose landing gear suddenly collapsed, causing the aircraft's nose to pitch down. The aircraft struck the runway on its propellers and skidded for approximately 350 metres before veering off the paved surface and coming to a stop on the adjacent grass. There were no injuries to the three occupants, though the aircraft suffered substantial damage.
The investigation
SACAA AIID investigators examined the wreckage and the aircraft's maintenance history. The investigation focused on the structural integrity of the landing gear assembly. Physical evidence showed that the nose landing gear trunnion had detached from the keel during the impact. The inspection also noted damage to the propellers, radar dome, and various nose gear components.
To determine the cause of the structural failure, fragments of the nose gear drag brace bracket were recovered and subjected to metallurgical analysis. The analysis of the magnesium alloy component revealed no evidence of pre-existing fatigue or material defects. Instead, the fracture surfaces indicated that the component failed due to a sudden, severe, transient overload.
Findings
- The aircraft was being operated for type conversion training under the supervision of a qualified instructor.
- All maintenance documentation for V5-SMA was found to be in order, with no identified defects in the landing gear's recent overhaul or inspection history.
- The primary cause of the landing gear failure was a hard landing or a subsequent bounce, which exerted enough force to cause the nose gear drag brace bracket to fail.