Accident Overview
Witnesses reported that the helicopter entered a hard left turn, nearly reaching an inverted position, before descending rapidly and impacting the ground. The pilot was flying from the left seat.
Inspection Findings
Post-accident examination of the left cyclic controls revealed that the metal connector for the left cyclic stick was broken in half. Further investigation of the cyclic stick quick disconnect locking nut showed that it was held in place on the connector by only one thread. When properly installed, the locking nut engages six threads on the connector. With the nut backed out to one thread, movement of the cyclic stick would not produce a corresponding change in the lateral control hydraulic servos.
Maintenance History
The cyclic was last removed approximately 80 flight hours prior to the accident during maintenance. The source does not specify the nature of that maintenance.
Safety Notice
On July 17, 1984, Bell issued an Operations Safety Notice that included the following caution: "Flight crews are cautioned to assure quick removal flight controls are properly installed prior to operating the helicopter." According to the source, prior to this notice, no requirements existed to verify proper installation of such controls.