What happened
On July 21, 2001, a Cap Aviation G 202, registration F-PQUX, was performing an aerobatic training flight at the Ancenis aerodrome. The pilot was executing a series of maneuvers, including a vertical climb, a half-loop, and a two-point roll, while in radio contact with a ground instructor. Witnesses observed the aircraft traveling at approximately 300 km/h at an altitude of 1,500 feet.
During a level flight phase following these maneuvers, the horizontal stabilizer and vertical fin suddenly detached from the fuselage. The separation caused the aircraft to lose control and crash near the threshold of runway 08. The impact occurred less than 10 seconds after the structural failure. The pilot, who was the sole occupant, was killed in the accident. The aircraft was destroyed.
The investigation
The investigation focused on the structural failure of the empennage. Investigators examined the wreckage at the Aeronautical Test Center in Toulouse (CEAT), specifically analyzing the bond lines of the composite structure. Laboratory tests revealed that the failure occurred at the fiber/resin interface rather than through typical adhesive or cohesive failure.
Technical tests demonstrated that the use of acetone, as prescribed in the manufacturer's manual for surface preparation, had a chemically aggressive effect on the epoxy resin matrix. This process created microscopic cavities and exposed the carbon fibers. Furthermore, the investigation looked into the assembly process of the kit, noting that the mechanical strength of the bonds in the kit-built sections differed from those produced in the factory.
Findings
- The primary cause of the accident was the in-flight separation of the tail section due to failures in the adhesive bonds performed during the final assembly of the kit.
- The surface preparation method recommended by the manufacturer, which involved cleaning with acetone, likely caused a degradation of the resin matrix, weakening the structural integrity of the bond.
- A lack of a specialized maintenance or inspection program for a high-stress aerobatic airframe contributed to the accident.
- The pilot had been alerted to significant play in the horizontal stabilizer by another pilot approximately two weeks prior to the accident, but this information was not communicated to the operator or maintenance personnel.
- The absence of an accelerometer or flight data recorder meant that any instances of exceeding structural load limits during aerobatic maneuvers could not be monitored or used to trigger inspections.