Elfe S4-A stürzt nahe Birrfeld nach Verlust von Steuerflächen ab

Am 31. August 1986 stürzte ein Neukom Elfe S4-A 2 km südwestlich des Flughafens Birrfeld in der Schweiz ab. Der Pilot hatte an diesem Tag bereits mehrere kurze Flüge absolviert, bevor er zu einem längeren Flug aufbrach. Etwa zwei Stunden nach dem Start beobachteten Zeugen, wie das Segelflugzeug in der Luft Teile verlor, gefolgt von unkontrollierten Manövern. Das Segelflugzeug stürzte aus 250 Metern steil ab, was zum Tod des Piloten und zur Zerstörung des Flugzeugs führte. Die offizielle Untersuchung deutete auf einen wahrscheinlichen mechanischen Defekt der Höhenruderkontrolle hin.

1. Cruise near Birrfeld: After a cross-country attempt from Birrfeld, the Elfe S4-A was cruising at low to moderate altitude near the home airfield, apparently returning to join the circuit.
2. High airspeed attained: Witnesses and barograph data indicate the glider accelerated to a very high speed, likely near or above the 210 km/h limit, at low altitude with little height margin.
3. Elevator inputs at speed: At this elevated speed, the pilot made significant pitch control inputs (pulling on the stick), subjecting the all-flying tailplane torque tube and rear fuselage to high bending and torsional loads.
4. Elevator structure failure: The elevator torque tube on the left side bent and fractured under load, leading to the left elevator half departing the aircraft and the right half being torn from its securing mechanism.
5. Tail and fuselage breakup: Loss of the elevator surfaces and associated loads caused severe torsion and structural failure of the rear fuselage, with multiple tail and fuselage pieces separating in flight and scattering along the flight path.
6. Uncontrolled high-speed maneuvers: With the elevator lost, the glider entered uncontrolled steep dives, a pushed-over looping and rolling motions, accompanied by strong vibrations and canopy breakage that likely impaired or removed the pilot’s ability to respond.
7. Crash - fatal: Approximately 2 km southwest of Birrfeld, the uncontrollable glider descended from about 250 m in a steep attitude, impacted a dirt road, overturned, and was destroyed, fatally injuring the pilot.