On May 13, 1988, a Mcdonnell Douglas 369D (registration N4943T) operated by Cherry Helicopters, Inc. was involved in an aviation accident near Waialua, HI. Investigators recorded the probable cause as: FAILURE TO FOLLOW PROCEDURES ESTABLISHED BY THE MANUFACTURE FOR UNCOMMANDED TRIM INPUTS AND HIS DECISION TO MAKE A HOVER APPROACH TO LANDING. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
A helicopter returning for another load experienced an uncommanded left roll. The pilot regained control, released the cable, but the helicopter rolled left to 45 degrees, climbed, and crashed into a ditch. Metal particles were found in the trim actuator switch; the pilot had reset circuit breakers.
Incident Overview
The helicopter was returning to its long line pickup point for another load when it entered an uncommanded left roll. The pilot regained control of the helicopter and released the long line cable. Subsequently, the pilot entered a shallow, slow approach to a hover in a vacant area. As the skids neared the ground, the helicopter rolled left to an angle of 45 degrees, began to climb, and then crashed into an irrigation ditch.
Examination and Findings
Post-accident examination revealed metal particles contaminating the trim actuator switch. According to the manufacturer, the helicopter is controllable with a malfunctioning trim system; however, the circuit breakers should be pulled. The pilot stated that he had reset the circuit breakers during the event.