Duo Discus left wing fails from spar bonding defect; both crew bail

Both occupants of a Duo Discus bailed out under parachutes after the left wing failed during a thermal flight near Heppenheim; aircraft substantially damaged; no injuries. At ~2,000 m AGL on a straight westbound glide at ~150 km/h GS the pilot pulled the elevator to slow; the left outer wing broke and folded upward, yawing the glider abruptly left. Full right aileron prevented loss of control while the crew bailed — the side-hinged canopy needed considerable force and did not separate. Examination found a 'mirror-smooth' bonding defect between spar web flange and upper CFK cap. A similar Discus CS wing failure occurred in France 4 days later.

1. Aerotow + thermal flight near Heppenheim: The Duo Discus launched by aerotow and was thermalling near Heppenheim around 16:30 in CAVOK conditions, carrying no water ballast.
2. Brand-new aircraft; first flight on type: The glider had been certified airworthy only two weeks earlier and had flown just 16 launches and 18 hours, all aerotows with two aboard — the pilot's first flight on the type.
3. Spar web/cap bonding defect: The wing spar had a manufacturing bonding defect at the shear web/cap joint; the mirror-smooth break surface showed an adhesive failure rather than overload.
4. Left wing breaks at slow-down input: In level flight at about 2,000 m AGL and 150 km/h, the pilot pulled the elevator to slow down; the left outer wing broke at the main spar just outboard of the aileron drive.
5. Wing folds upward; abrupt left yaw: The outer wing piece folded upward and the glider abruptly yawed and rolled left under the asymmetric drag and lift loss.
6. Full right aileron stabilises glider: The front-seat pilot applied full right aileron and managed to stabilise the damaged glider enough to prevent immediate loss of control, giving the crew a window to evacuate.
7. Crew bails; canopy doesn't separate: Both occupants bailed out. The canopy, meant to separate at frangible hinges, stayed attached despite a bent hinge pin and a broken rear fitting; both still deployed their parachutes.
8. Both safe; glider in city forest: Both occupants landed uninjured by parachute. The glider crashed into Lampertheim's forest, right wing caught in trees, and was substantially damaged; forest damage was minor.