What happened
On April 19, 2004, at approximately 09:30, an Ultrasport 496 helicopter, operated by Wei Hua Aerospace Industrial Co., Ltd., departed from the Feilong Airfield in Tainan for a weight-bearing test. The aircraft was configured with the pilot in the right seat and two bags of gravel, each weighing approximately 88 pounds, secured in the left seat.
At approximately 09:50, the aircraft crashed into a watermelon field within the Zengwen Riverbed near the Guoxing Bridge. Witnesses reported seeing the helicopter hover at an altitude of approximately 300 feet, where it began to oscillate violently in all directions before descending at a steep angle. The impact lasted less than ten seconds, resulting in the total destruction of the aircraft and the death of the pilot.
The investigation
The Taiwan Transportation Safety Board (TTSB) examined the aircraft's maintenance and flight records, as well as the physical wreckage. The investigation established that the aircraft lacked a complete set of maintenance and test flight records, and no formal flight test procedures were in place. Furthermore, the aircraft was not operating in compliance with the Civil Aviation Act.
Physical inspection of the wreckage revealed significant damage to the fuselage, including a broken windshield and deformed structural components. The main rotor blades showed signs of failure, with one blade broken at the root and the other partially lodged in the windshield. The engine and transmission systems sustained heavy damage due to the impact, though investigators determined that the engine and airframe damage was caused by the crash itself rather than a pre-existing mechanical failure. The investigation also noted that the aircraft's weight and balance for the specific flight were not recorded prior to takeoff.
Findings
- The pilot failed to perform an accurate weight and balance calculation prior to the flight, which likely led to insufficient power during the mission and an inability to maintain control during an emergency descent.
- The operator lacked comprehensive maintenance and flight test records, as well as established flight test procedures, which compromised flight safety.
- The flight was conducted in violation of the Civil Aviation Act.
- The definition of "fuel weight" for ultra-light aircraft under Article 2 of the Civil Aviation Act is prone to misinterpretation.
- The damage to the airframe and engine was a direct result of the impact with the ground.
- Weather conditions at the time of the accident were not a contributing factor.