On September 23, 1990, a Glaser-dirks DG 400/17 (registration N567DA) was involved in an aviation accident near Truckee, CA. Investigators recorded the probable cause as: The control quick disconnect spring pin had not been fitted into the control hole as recommended, which resulted in the quick disconnect to the spoiler disconnecting from the right hand spoiler rod end ball. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A powered glider pilot performed a spoiler check before landing; the right spoiler remained deployed, causing asymmetrical lift and loss of control. The quick disconnect spring pin was not fitted as recommended.
Incident
During the landing approach, the pilot of a self-launched powered glider conducted an operational check of the spoiler system. Following retraction, the right-hand spoiler remained deployed, creating an asymmetrical lift condition. The pilot was unable to maintain control of the aircraft, and it collided with the ground short of the runway.
Examination
Post-incident examination revealed that the control quick disconnect spring pin had not been fitted into the control hole as recommended. This resulted in the quick disconnect separating from the right-hand spoiler rod end ball, which prevented the spoiler from retracting fully. The aircraft was equipped with spoilers on both wings, and the system included a quick disconnect mechanism secured by the spring pin. Without the pin properly installed, the connection could not maintain integrity during operation.
Probable cause
The control quick disconnect spring pin had not been fitted into the control hole as recommended, which resulted in the quick disconnect to the spoiler disconnecting from the right hand spoiler rod end ball.