DG-FLUGZEUGBAU GMBH DG-500MB

Full Narrative

In a written statement, the pilot reported that the accident flight was his second flight of the day. After conducting a series of practice maneuvers, he was returning back to the airport. The pilot entered a right traffic pattern and configured the glider for landing. With the landing gear extended and the flaps set at 10 degrees, he opened/tested the spoilers. While on the base leg of the traffic pattern, he noticed the glider was low, and as he maneuvered onto final approach, he closed the spoilers (forward activation of the lever). The glider’s sink rate was excessive and he observed that the spoilers visually appeared to be deployed although the control lever was in the full-forward (closed) position. He manipulated the lever back and forth, which had no effect on the spoiler position. The glider impacted railroad tracks about 1,000 feet from the approach end of the runway and sustained substantial damage to the fuselage and wings in the accident sequence.

The pilot opined that the accident was a result of him mixing up the spoiler lever with the flap lever. He thought he was wrongly activating the flap control, not the spoiler control, which were in close proximity to one another. This led to the spoilers remaining deployed during the final approach.

An inspector from the Federal Aviation Administration (FAA) performed a post accident examination of the glider. He stated that the right wing spoiler’s lower plate appeared to have been rubbing the aft spoiler bay wall until it scraped off the resin. It appeared to have scrapped enough material that it caught on a fabric seam (once sealed in the resin) and would not retract (would not push past the catch due to the exposed fabric edge. The location of the scrape marks and the fabric seam the spoiler caught on put the spoilers at half extension, which the FAA inspector thought was consistent with the lack of performance the pilot reported. The left wing spoiler’s lower plate bushings were tight, with no play.