Accident Overview
On 26 January 2003, at approximately 1015Z, a Cessna 172 (registration ZS-FIE) was conducting a private flight from Rand Airport (FAGM) to Lanseria Airport. The aircraft was taking off on Runway 29 in CAVOK weather conditions, with a wind of 10 knots from the south-west and a temperature of 25°C.
Sequence of Events
Approximately 50 metres into the take-off run, at an airspeed of about 30 knots, the pilot heard a loud bang. The nose of the aircraft then dropped, and the aircraft skidded on the tarmac for a further 30 metres before coming to rest on the runway. Both the pilot and the passenger vacated the aircraft with no injuries.
Aircraft Damage
Inspection revealed that the nose gear fork had failed and separated from the nose gear oleo strut during the take-off run. This caused the propeller to strike the ground. The right wing also sustained damage when it made contact with the runway.
Probable Cause
The nose gear fork failed as a result of fatigue cracks in both fork arms that had propagated through the material over time, weakening the fork to such an extent that the remaining material could no longer sustain the load, resulting in an overload failure. It is further believed that nose wheel shimmy over a long period caused cyclic loading of the nose fork and led to the formation of the fatigue cracks in both fork arms.