History of Flight
On 18 March 2013 at approximately 1300Z, a test flight was conducted at Wonderboom Aerodrome (FAWB) following a maintenance periodic inspection (MPI) on the aircraft. During the approach for landing, the pilot selected the landing gear down, but the right-hand main landing gear failed to lock in the down position. The pilot attempted to lower the gear using the emergency system, but it did not succeed. The aircraft landed with the left-hand main landing gear and nose landing gear down and locked, while the right-hand main landing gear remained unlocked. The accident occurred on Runway 29 at GPS coordinates S25°39.0' E028°13.0' during daylight conditions.
Damage to Aircraft
The aircraft sustained minor damage to the right-hand wing tip and substantial damage to the right-hand elevator and right-hand stabilizer. No other damage was reported.
Injuries to Persons
The pilot escaped unharmed. No injuries were recorded.
Tests and Research
After recovery, extension and retraction tests were performed on the landing gear. The gear cycled five times with the normal system, retracting correctly each time, but during extension the right-hand main landing gear failed to lock every time. Three further attempts with the emergency system yielded the same result. The actuator from the right-hand main landing gear was removed and dismantled. The ram was found severed a short distance from the outer tip (down side), with the fractured surface displaying clear signs of fatigue failure. The left-hand main landing gear actuator was also removed and examined; Magnaflux inspection revealed a crack in the same position as the right-hand ram.
Probable Cause
The Ram from the right-hand main landing gear actuator failed due to fatigue, which prevented the right-hand main gear from extending to the full down and locked position.