What happened
On 07 September 2003, a PIPER PA-30, registration ZS-SWI, was conducting a training flight departing from and returning to Lanseria Aerodrome. During the approach for landing on Runway 06L, the instructor pilot attempted to extend the landing gear. While the gear selection was made, the green light indicating the gear was down and locked failed to illuminate.
In an attempt to rectify the issue, the pilot cycled the landing gear and subsequently utilized the emergency extension lever. Despite these efforts, the gear remained problematic. During a fly-past, air traffic control confirmed that the left-hand main landing gear was only partially extended. To ensure a safe arrival, the instructor performed a landing with both engines shut down and propellers feathered. Upon touchdown, the left-hand main gear collapsed, causing the aircraft to ground loop approximately 60 degrees. The aircraft sustained minor damage to the left-hand wing, but there were no injuries to the three people on board.
The investigation
The investigation focused on the mechanical failure of the landing gear extension mechanism. Investigators reviewed the aircraft's maintenance history, noting that the most recent Mandatory Periodic Inspection (MPI) had been completed on 10 July 2003, with 82 flight hours accumulated since that inspection.
Findings
The investigation established that the left-hand main landing gear inner push-pull cable was improperly swaged at the rod-end fitting located at the gearbox transmission beneath the cockpit floor. Additionally, it was determined that a lack of lubrication may have caused the push-pull cable to become stiff, which likely contributed to the cable pulling free from its fitting.