NTSB Identification: SEA99LA151.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Monday, August 30, 1999 in KENT, WA
Probable Cause Approval Date: 01/18/2001
Aircraft: ROTORDYNE 200, registration: N85Z
Injuries: 1 Fatal.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The co-owner/builder had been engaged in resetting the angle of attack (pitch angle) of the main rotor blades previous to the accident. Witnesses reported observing the gyrocopter depart to the south, proceed west, and then execute several oscillatory, rocking or pitching like maneuvers after which the aircraft entered a steep descent to the ground. Post-crash examination revealed that all eight of the main rotor blade pitch adjustment bolts were loose. Examination of the upper outboard shim plate of each blade attach bar revealed markings which clearly established a pitch bolt torque of 190 inch-pounds. Release of the main rotor blade pitch adjustment bolts would allow a rotor blade pitch change and subsequent loss of control.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The owner/builder's failure to properly torque the rotor blade retaining bolts.

Full narrative available

Index for Aug1999 | Index of months