JS3 strikes trees on approach with its sustainer left extended

A Jonker JS3 struck trees on approach to New Castle; the pilot was unhurt and the right wing substantially damaged. After running the sustainer engine briefly and shutting it down, the pilot left it extended, so it kept adding drag as he configured to land. Fighting an excessive sink rate, he reached to reduce flap but selected full negative instead, deploying the spoilers and steepening the descent. On the turn to final he levelled the wings for a controlled contact with the trees.

1. Approach with sustainer: During the approach and descent to New Castle, the pilot deployed and operated the jet sustainer for about 90 seconds in the motorglider.
2. Jet sustainer left extended: After shutting down the jet sustainer, the pilot forgot to stow it, leaving it extended and increasing drag during the subsequent approach.
3. Landing configuration set: After entering the traffic pattern, the pilot extended flaps and landing gear to configure for landing while the jet sustainer remained extended.
4. Incorrect flap selection: Noticing a higher-than-normal sink rate, the pilot tried to reduce flaps but inadvertently selected full negative flap, which also deployed the spoilers and increased the sink rate.
5. Unable to clear trees: While turning from base to final in the traffic pattern, the pilot recognized that a collision with a nearby tree line was likely and leveled the wings in anticipation of tree contact.
6. Crash - no injury: The glider struck trees short of the intended landing area, substantially damaging the right wing, and the pilot was uninjured.