Bergfalke IV releases at 10 m after winch problem, hits runway hard

A Bergfalke IV was heavily damaged on a winch launch from RWY 27 at Gardelegen (Germany); both occupants were seriously injured. The visiting club had brought its own six-drum Busio winch to a flying camp. At about 10 m AGL the pilot perceived the cable pull dropping and released. The glider struck the runway twice and ground-looped through a half turn, coming to rest about 400 m beyond the start, facing back along the launch axis. A loop of the previously used Dyneema cable had jumped a drum flange and wrapped the through-shaft, blocking all six drums.

1. Winch launch from RWY 27 ~17:00 LT: At about 17:00 LT on 21 July 2015 the Bergfalke IV began a winch launch from RWY 27 at Sonderlandeplatz Gardelegen (EDOC). The guest club ran the launch with its own six-drum Busio winch brought along for a Fliegerlager.
2. Cable loop wraps winch shaft: A loop of the previously-used high-strength Dyneema winch cable had jumped over the flange of its drum and wrapped the through-shaft that drives all six drums, blocking the shaft. The pull on the active drum therefore dropped during the launch.
3. Winch pull drops at ~10 m: After the glider reached about 10 m above the ground in the initial climb the pilot perceived the winch cable tension decrease significantly.
4. Release at ~10 m: In response to the loss of winch pull the pilot released the cable at roughly 10 m height above the runway.
5. Two hard impacts, ½-turn ground loop: After the release the glider struck the runway twice with hard impacts along the takeoff path, then ground-looped through about half a turn around the vertical axis (Ringelpietz) and came to rest about 400 m beyond the start position, facing back along the launch axis.
6. Heavy damage, both seriously injured: The fuselage underside was pressed in up to the main wheel; both wings developed roughly 15 cm cracks at the outer end of the brake-flap box, parallel to the longitudinal axis; control rods of the elevator and flap circuits were damaged consistent with the hard impacts. Both occupants were seriously injured.