What happened
On 01 March 2003, a PA-30 aircraft, registration ZS-DXL, departed Rand Aerodrome on a private flight destined for Pietersburg Aerodrome. Shortly after takeoff, the pilot observed that the airspeed was lower than expected. Upon attempting to retract the landing gear, the pilot discovered that the undercarriage failed to move to the up position despite the lever being selected.
In an effort to rectify the situation, the pilot attempted to recycle the gear and utilized the emergency extension system, but neither action was successful. During a fly-past of Pietersburg Aerodrome, Air Traffic Control (ATC) alerted the pilot that the undercarriage was not fully down and locked. Following further confirmation of the gear status from ATC at Rand Aerodrome, the pilot elected to return to the departure airfield.
The aircraft landed on Runway 11 with the landing gear in an intermediate position, the flaps retracted, and the propellers feathered. To mitigate the impact, the runway was sprayed with foam. While the underside of the fuselage sustained damage during the landing, the propellers remained undamaged as the engines had been shut down and the propellers positioned horizontally prior to touchdown. There were 0 fatalities and 0 injuries.
The investigation
SACAA AIID investigators examined the mechanical state of the landing gear assembly and performed a metallurgical analysis of the components. The investigation focused on why the undercarriage failed to retract and why the emergency system was ineffective.
Findings
- The investigation determined that the right-hand main landing gear torque link bolt came adrift.
- This failure occurred because the bolt securing nut lacked a required split pin.
- The absence of the split pin allowed the bolt to migrate out of position, causing the main wheel to turn sideways and become wedged within the wheel well.