Phoebus C rudder turnbuckle failed in flight — owner mod, first flight after

During a local thermal flight from Oerlinghausen, the pilot-owner of a Phoebus C was fatally injured. About five minutes after launch the pilot radioed a PAN-PAN call reporting rudder problems. The glider departed controlled flight three times, twice recovering, before descending near-vertically between trees; it clipped a pine at about 13 m and impacted a forest path. Inspection found owner-retrofitted turnbuckles in the rudder cables with inadequate thread engagement and improper safety wiring; under load the right turnbuckle pulled out and severed rudder control. This was the first flight after the modification.

1. Owner-retrofitted turnbuckles: The owner-pilot had recently added turnbuckles (Spannschlösser) to the rudder cables — non-standard for the Phoebus C — to adjust pedal inclination. BFU inspection found only 1–2 threads engaged on the right side and safety-wire not installed to specification on either side.
2. First flight after the modification: Launched at 12:40 from Oerlinghausen for a planned local thermal flight; the accident flight was the first on type since the modification.
3. Right turnbuckle pulled out in flight: Around 12:45 the pilot radioed a PAN-PAN call about rudder problems; under load the brass nut thread tore out, severing rudder control.
4. Spin and recovery: Glider entered a spin, recovered, and climbed slightly back toward the airfield.
5. Repeated right-wing departures: In a right turn with "pumping" motion and decreasing airspeed, the glider rolled off over the right wing twice — each time recovering to level.
6. Vertical impact between trees: A third right-wing departure was not recovered; the glider descended near-vertically, clipped a pine at ~13 m AGL, and impacted a forest path. Pilot fatally injured; aircraft destroyed.