What happened
On 25 August 2014, a Cessna 414A, registration ZS-FPU, was conducting a maintenance test flight at East London Aerodrome. The flight was intended to verify repairs made to a hydraulic leak in the left main wheel well. During the final approach to Runway 06, the pilot attempted to deploy the undercarriage, but the left main gear failed to extend. Despite the deployment of the emergency blow-down system, only the nose and right main gear locked into position.
The pilot requested a flypast to allow air traffic control to visually confirm the gear configuration, and the controller confirmed the left gear remained retracted. The pilot subsequently performed a landing using only the nose and right main gear. As the aircraft decelerated, the left wing made contact with the runway surface. The pilot was unable to maintain directional control, causing the aircraft to veer left and come to a rest on the grass adjacent to the runway. There were no injuries to the pilot, and the aircraft sustained substantial damage to the left wing, left propeller, and underbelly.
The investigation
SACAA AIID investigators examined the aircraft's recent maintenance history and the mechanical state of the landing gear assembly. The investigation established that the aircraft had been brought to an approved maintenance organization four days prior to rectify a hydraulic leak caused by corrosion porosity. A new rigid hydraulic line had been manufactured and installed to replace the defective part.
Post-accident inspection of the landing gear assembly revealed that the newly installed rigid pipe had separated from the main landing gear up-lock cylinder, leading to a secondary hydraulic fluid leak. Investigators also identified a crack in the supporting sleeve at the attachment point to the up-lock cylinder.
Findings
- The primary cause of the landing gear failure was the separation of the rigid hydraulic pipe from the up-lock cylinder.
- A crack was present in the supporting sleeve at the up-lock cylinder attachment.
- The failure of the hydraulic line prevented the left main gear from extending, even when the emergency system was utilized.
- Weather conditions at the time of the accident were clear with good visibility, and the pilot was appropriately rated and fit for the flight.