NTSB Identification: WPR12IA248
14 CFR Part 91: General Aviation
Incident occurred Tuesday, May 22, 2012 in Seattle, WA
Probable Cause Approval Date: 01/13/2014
Aircraft: EUROCOPTER AS 350 B2, registration: N105TV
Injuries: 2 Uninjured.

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

The pilot reported that he had just entered a slow orbit when the helicopter began to vibrate severely. The vibration was continuous and so severe that the pilot diverted to a nearby airport and landed. Postincident examination of the helicopter revealed that one of the tail rotor pitch change link bolts (that connected the control rod to the blade’s pitch arm) was missing. The incident flight took place after a 100-hour maintenance inspection that was completed earlier that day. The inspection included maintenance and service to the tail rotor assembly. The pilot reported that the pitch change link bolt was not correctly tightened and secured during the maintenance and subsequently loosened and released during the flight. The missing bolt resulted in an asymmetrical pitch between the two tail rotor blades, which caused the vibration.

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

Failure of maintenance personnel to ensure that the tail rotor pitch change link bolt was properly secured, which resulted in an in-flight separation of the bolt and subsequent vibration.

Full narrative available

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