What happened
On the evening of June 22, 1997, a DR 400-180, registration F-GKQF, departed from Etampes aerodrome for a local flight. The aircraft was operated by the Groupement Aéronautique du Ministère de l’Air (GAMA) and was carrying a pilot and three passengers.
After departing at 19:45, the pilot transitioned to a local flight pattern, navigating near La Ferté-Alais and Mondeville. Radar tracking from Paris Orly ceased at approximately 20:08. When the aircraft failed to return by nightfall, an alert was raised. The wreckage was discovered the following morning in a wooded area near Mespu and was found with the aircraft in a steep, 60-degree nose-down attitude and a 90-degree right bank.
All four fatalities occurred during the impact, which was of such violence that the rear passengers were ejected from the cabin.
The investigation
The investigation focused on the distribution of debris and the structural integrity of the airframe. Investigators found significant portions of the right wing debris, including a section of the spar, scattered over 1,000 meters from the main wreckage.
Technical examination of the recovered spar revealed that the structure was not correctly closed, leaving it partially open. Analysis of the fracture surfaces showed that the lower flange failed in pure tension, while the upper flange failed in flexion. This sequence indicated that the structural box was no longer properly bonded, causing the upper flange to lose its intended mechanical support.
Findings
- The investigation established that the right wing separated in flight.
- The primary cause was manufacturing defects involving improper adhesive application and insufficient pressure during the assembly of the spar.
- Evidence showed that protective varnish had seeped into the adhesive joints, preventing a proper bond between the web and the flanges.
- These defects led to accelerated structural aging and weakened the wing's ability to withstand standard load factors within the normal flight envelope.
- There was no evidence of an intentional maneuver exceeding the aircraft's structural limits or a prior impact damage that could have initiated the failure.