WPR12IA248

The pilot reported that he had just entered a slow orbit when the helicopter experienced what he described as a severe vibration. 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 (to the pitch arm) was missing. The incident flight followed a 100-hour maintenance inspection that concluded earlier that day. The inspection included maintenance and service to the tail rotor assembly. The pilot reported that the pitch change link bolt (to pitch arm) was not correctly tightened and secured while in maintenance and subsequently loosened and released during the flight.

On May 22, 2012, about 1430 Pacific daylight time, a Eurocopter AS-350 B2, N105TV, sustained minor damage following an in-flight separation of a tail rotor pitch change link bolt while maneuvering near the Seattle-Tacoma International Airport (SEA), Seattle, Washington. The airline transport pilot and aerial photographer crewmember were not injured. The helicopter was registered to KING Broadcasting Company, Seattle, Washington, and operated as an electronic news gathering flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and a company flight plan was activated for the flight that originated from Boeing Field (BFI), Seattle, Washington, about 1415. The pilot's planned destination was Seattle Private Number One Heliport (WN01). The pilot reported that he had just entered a slow orbit, about 1,200 feet above the ground, when the helicopter experienced what he described as a severe vibration. The vibration was continuous and so severe that the pilot diverted to BFI for landing. He reported that just before landing, with full right pedal inputs, the helicopter entered a slow turn to the left, which continued until touchdown on the taxiway. The pilot reported that a postincident examination of the helicopter revealed damage to the tail boom assembly and support structure. He reported the exam also revealed that one of the tail rotor pitch change link bolts (to the pitch arm) was missing and likely released during the flight, which resulted in an asymmetrical pitch between the two tail rotor blades and subsequent vibration. The accident flight followed a 100-hour maintenance inspection that concluded earlier that day. The inspection included maintenance and service to the tail rotor assembly. The pilot reported that the pitch change link bolt (to pitch arm) was not correctly tightened and secured while in maintenance and subsequently loosened and released during the flight.