What happened
On June 16, 2018, at approximately 19:00 UTC, a Camachui single-seat glider, registration LV-X227, was involved in a loss of control accident near the Esperanza aerodrome in Santa Fe, Argentina. The aircraft, which was being operated for general aviation training, had been towed to an altitude of 500 meters before the pilot released the towline. Following approximately 50 minutes of stable flight, the pilot began a landing pattern.
Observers at the airfield noted that while the initial, base, and final approach phases appeared standard, the aircraft began to exhibit oscillations that grew in amplitude with each cycle. During the third or fourth oscillation, the glider adopted an extreme nose-up attitude, reaching an altitude of roughly 30 meters, before pitching down sharply and impacting the ground. The pilot survived the impact and was rescued by local firefighters.
The investigation
The investigation focused on the flight dynamics of the experimental aircraft and the lack of specific operational documentation. Investigators examined the aircraft's weight and balance, noting that while the total weight of 353.09 kg was within the maximum takeoff weight of 404 kg, the flight manual for the Camachui did not define the allowable center of gravity (CG) range. This lack of documentation made it impossible to verify if the aircraft was operating within its intended longitudinal stability limits.
To understand the aerodynamic behavior, investigators performed visual field tests and weight tests using a similar model, the LV-X2 . (Camui HB4 Club), to simulate different loading configurations, including the use of parachutes and various weights.
Findings
- The aircraft experienced unstable longitudinal oscillations that culminated in a loss of control.
- The flight manual for the LV-X227 lacked defined limits for the center of gravity position.
- The lack of approved operational limitations for experimental aircraft contributed to uncertainty regarding the aircraft's flight envelope.
- The pilot was operating the aircraft with limited flight experience in this specific type.
Safety action
- The investigation recommended that the National Civil Aviation Administration (ANAC) establish a control program for all flight manuals or operational limitation cards for experimental aircraft registered in Argentina.
- A recommendation was made to implement specific requirements for pilot conversion training to ensure pilots are properly familiarized with the unique maneuvers of specific aircraft types.