What happened
On January 20, 2001, at approximately 14:00 local time, a Jabiru LSA 55/3J, registration U-C01, was conducting a test flight near the CMT Flying Club's temporary airstrip in Bang Phra, Si Racha, Chonburi. The flight was being performed at an altitude of 500 feet to gather data for the renewal of the aircraft's special airworthiness certificate.
Approximately five minutes into the flight, while flying over the Bang Phra Reservoir, the engine power decreased. The pilot attempted to rectify the issue by increasing power, which caused the engine to vibrate and produce abnormal noises. Upon reducing power to manage the vibration, the aircraft continued to lose altitude. Unable to maintain flight, the pilot performed an emergency landing on uneven, sloping terrain near the reservoir's edge.
During the landing, the nose wheel struck a mound of earth, causing the aircraft to lift and impact the ground. The nose gear collapsed, and the aircraft slid approximately 50 meters before the nose dug into another mound. This caused the tail to pitch upward, resulting in the aircraft capsizing with its fuselage upside down. There were two persons on board, the pilot and a passenger, both of whom escaped without injury, though the aircraft sustained extensive damage.
The investigation
The investigation examined the engine's maintenance history and the circumstances surrounding the flight. Investigators found that the engine had a recurring history of component failures, including leaking exhaust manifold gaskets and cylinder head gaskets, as well as leaking intake and exhaust valves. Specifically, during the post-accident inspection, leaks were found in the exhaust valves of cylinders number 2, 3, and 4, along with a loose valve adjustment screw on cylinder number 2.
Furthermore, the investigation revealed that maintenance records were incomplete or inaccurate. A previous incident in September 2000, where the propeller struck the ground during a test flight, had not been reported to the Department of Civil Aviation. Additionally, repairs following that incident were reportedly conducted by a maintenance unit not authorized by the authorities.
Findings
- The primary cause of the accident was engine failure occurring at an insufficient altitude to allow for a controlled recovery.
- Recurring engine defects, specifically leaking valves and gaskets, contributed to the mechanical failure.
- The pilot's attempt to rectify the power loss by increasing throttle exacerbated the engine vibration and instability.
- Inadequate maintenance documentation and the use of unauthorized repair facilities were identified as significant contributing factors.