On 29 October 1917, "Leutnant der Reserve" Heinrich Gontermann, "Staffelführer" of "Jasta" 15, was performing aerobatics when his triplane broke up. Gontermann was killed in the ensuing crash landing. "Leutnant der Reserve" Günther Pastor of "Jasta" 11 was killed two days later when his triplane broke up in level flight. Inspection of the wrecked aircraft showed that the wings had been poorly constructed. Examination of other high-time triplanes confirmed these findings. On 2 November, "Idflieg" grounded all remaining triplanes pending an inquiry. "Idflieg" convened a "Sturzkommission" (crash commission) which concluded that poor construction and lack of waterproofing had allowed moisture to damage the wing structure. This caused the wing ribs to disintegrate and the ailerons to break away in flight.