NTSB Identification: SEA95LA227.
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Accident occurred Wednesday, September 20, 1995 in YAKIMA, WA
Probable Cause Approval Date: 04/29/1996
Aircraft: TEXAS HELICOPTER OH-13E, registration: N38115
Injuries: 1 Uninjured.

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

IMMEDIATELY AFTER LIFTING OFF AND REACHING TRANSLATIONAL LIFT, THE PILOT LOST COLLECTIVE PITCH CONTROL AND ROTOR RPM BEGAN TO DECREASE. THE HELICOPTER BEGAN AN UNCONTROLLED DESCENT AND IMPACTED WITH A POND. EXAMINATION REVEALED THAT AN ATTACHMENT BOLT IN THE SCISSOR ARM ASSEMBLY OF THE PITCH CONTROL SUPPORT ASSEMBLY HAD FAILED. EXAMINATION OF THE FRACTURE SURFACE REVEALED THAT THE BOLT HAD FAILED IN FATIGUE, WITH MULTIPLE CRACKING ORIGINS EMANATING FROM THE THREADS OF THE BOLT.

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

FATIGUE FAILURE OF THE BOLT ATTACHING THE SCISSOR ARM ASSEMBLY TO THE PITCH CONTROL SUPPORT ASSEMBLY. THE FAILURE OF THE BOLT LED TO A LOSS OF COLLECTIVE PITCH CONTROL AND REDUCED ROTOR RPM.

Full narrative available

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