What happened
On 7 September 2023, a Raj Hamsa X Air, registration EI-CXC, departed from Runway 19 at Limetree Airfield in County Laois. During the initial climb, while the aircraft was approximately 50 to 60 feet above a hill on the takeoff path, the engine experienced several interruptions in power. The pilot attempted an emergency landing in a nearby agricultural field.
During the landing sequence, the aircraft's right wing strut struck a ground stake, causing the aircraft to spin. The impact caused the nosewheel and the right main wheel to separate from the airframe. The aircraft eventually came to rest in a field. While the pilot was uninjured, the passenger sustained one injury to the back. The aircraft sustained substantial damage.
The investigation
Investigators examined the wreckage and the engine components to determine the cause of the power loss. The engine, a Rotax 582, was stripped and inspected by specialists. The investigation also included laboratory testing of the fuel used in the flight.
Technical analysis of the engine revealed that the front piston had seized. The investigation found that the aluminum piston expanded at a different rate than the steel cylinder liner during the transition to full power. Additionally, fuel samples taken from the aircraft showed a high water content of 986ppm v/v, which could have further degraded engine performance.
Findings
- The primary cause of the engine failure was a cold seizure in the forward cylinder, where the piston expanded faster than the cylinder liner.
- A lack of sufficient engine warm-up at higher RPMs contributed to the seizure.
- The aircraft's brakes were unable to hold the engine at speeds above 2,500 RPM, preventing the pilot from performing a high-power warm-up or a full-power pre-takeoff check.
- The uphill gradient of the runway and the high water content in the fuel were contributing factors.
- The aircraft was operating near its maximum takeoff weight on a warm day, which limited the climb rate.
- The terrain and the low altitude at the time of the engine failure left little margin for a successful emergency maneuver.