What happened
On May 1, 2012, a Liberty XL-2, registration SP-AXL, was performing a series of flights at Warsaw-Babice airport. After completing an initial flight series and a 40-minute period on the apron, the pilot began a second series of flights, this time carrying a training candidate in the left seat.
The aircraft departed from runway 10R at 13:45. Approximately one minute after takeoff, while in a climb, the pilot notified Babice Radio of his intention to turn back, likely intending to land on runway 28L. During this maneuver, the aircraft entered a spin or a wingover, subsequently striking the runway with its left wing and the left side of the engine. The impact caused the aircraft to catch fire and slide across the runway. Both occupants sustained fatal injuries due to the impact with the runway surface.
The investigation
The PKBWL investigation examined the aircraft's maintenance history, engine performance, and the pilot's qualifications. The investigation noted that the aircraft had approximately 557 hours of total time. While the engine was found to be in airworthy condition, investigators identified issues with uneven fuel-air mixture combustion and oil burning in the rear cylinders. The investigation also reviewed the pilot's experience, noting he had approximately 20 hours of flight time specifically on the Liberty XL-2 model. Additionally, the investigation looked into the impact of high ambient temperatures on engine performance and the lack of specific guidance in the Airplane Flight Manual (AFM) regarding high-temperature operations.
Findings
- The primary cause of the accident was insufficient airspeed or excessive control inputs during a dynamic stall, which induced the spin or wingover.
- A contributing factor was likely improper engine operation or a FADEC warning caused by fuel vapor lock, resulting from high ambient temperatures following the aircraft's 40-minute soak on the sunlit apron.
- The pilot was operating from the right seat, which the commission noted could complicate emergency procedures.
- The aircraft's engine performance was reduced due to the high ambient temperature.