Overview
On 5 March 2003 at 0640Z, a PA-30 aircraft registered ZS-NKR was operating a domestic charter flight from Nelspruit Aerodrome (FANS) to Rand Aerodrome (FAGM). The pilot, who held a commercial license with 780.8 total flying hours and 102.0 hours on type, was the sole occupant. The weather was fine with scattered clouds and wind 070/5kt.
Sequence of Events
During the downwind leg for landing on Runway 11 at Rand Aerodrome, the pilot selected the undercarriage to the down position. The undercarriage failed to extend properly, and the electrical motor circuit breaker (CB) tripped with the undercarriage only partially extended. The pilot reset the circuit breaker three times, allowing approximately 2 minutes for the electrical motor to cool down, but the circuit breaker kept tripping. He then disengaged the electrical motor from the undercarriage torque tube system and attempted to lower the undercarriage using the manual extension lever, but to no avail. During a fly-past, air traffic control confirmed that the landing gear was only partially extended. The pilot was committed to execute a landing with the undercarriage not down and locked.
Probable Cause
The most probable cause for the undercarriage electrical motor circuit breaker to trip was that the electrical motor had overheated as a result of an overload due to a too high airspeed when the undercarriage was lowered prior to landing.