DFS Kranich II structural failure during aerobatics at Bellechasse results in fatality
On June 6, 1965, a DFS Kranich II experienced a structural failure during an aerobatic training flight at Bellechasse, Switzerland. The flight instructor and a student pilot were performing a looping maneuver when the right wing detached, causing the aircraft to crash. The student pilot successfully parachuted to safety, but the instructor was unable to escape and was killed on impact. The investigation revealed that the glider was overloaded for aerobatic maneuvers, contributing to the structural failure.
- Aerotow training flight: The instructor and student launched by aerotow from Bellechasse for a third dual aerobatic training flight in the DFS Kranich.
- Glider overloaded: For this flight the Kranich was about 45 kg above the maximum permitted weight for aerobatics, with the centre of gravity 24 mm ahead of the forward limit.
- No g-meter installed: The glider was not equipped with a required accelerometer, so the instructor had no direct indication of g-loads during aerobatic maneuvers.
- Looping pull-out: From about 620 m AGL the instructor demonstrated a looping, and at roughly 500 m AGL during the pull-out he applied a strong nose-up input that generated a peak structural load.
- Right wing failure: At about 30° nose-up attitude the right wing failed at the main attachment, rotated upward, and separated, leaving the glider uncontrollable.
- Student parachute escape: The student pilot exited his seat without difficulty and successfully descended under his parachute, while the rear canopy opened but the instructor did not or could not exit.
- Crash - fatal: The crippled glider crashed into a nearby field, destroying the aircraft and fatally injuring the instructor while the student remained unhurt.