Accident Overview
On January 18, 2010, at about 1733 eastern standard time, a Eurocopter AS 350 B2, registration N696BH, operated by Liberty Helicopters, Inc., experienced an in-flight vibration approximately 4 minutes after takeoff and landed at the West 30th Street Heliport (JRA), New York, New York. The flight originated from the Downtown Manhattan/Wall Street Heliport (JRB) at 1729 and was conducted under visual meteorological conditions with company VFR flight following, operating under 14 CFR Part 91 as a positioning flight. The helicopter sustained substantial damage; the commercial pilot, the sole occupant, was not injured.
Pilot Account
The pilot stated that during cruise flight at 600 feet, he announced his intent to land at JRA and was cleared to land on spot 3 behind another aircraft approaching from the north. At that time, he felt a vibration through the airframe, including the anti-torque pedals and cyclic. He maintained positive control and decided to continue the landing. The vibration remained constant during the approach. After touchdown on spot 3, he immediately began shutdown and applied the rotor brake. The vibration increased dramatically as rotor speed decreased. After the main and tail rotors stopped, the pilot exited and observed damage to the tail rotor and surrounding area. One pitch change link of a tail rotor blade was separated from its attach point at the blade, and the blade was out of its normally installed position.
Postaccident Inspection
During postaccident inspection by the Federal Aviation Administration (FAA) and Liberty Helicopters, Inc., a hole was found in the right side of the tailboom near station 3700, and the tailcone was damaged near station 4880.6. The pitch change link of one tail rotor blade was not connected to the blade control horn; the securing hardware (bolt, castellated nut, and cotter pin) was missing. The opposite end of the link remained attached to the pitch change spider assembly and was secured by a cotter pin. The tail rotor blade with the separated pitch change link exhibited paint transfer marks on its leading edge near the blade tip, consistent with the color of the tailboom, and abrasion on the leading edge. No dents were observed in that area. The other tail rotor blade's pitch change link was properly connected at both ends with cotter pins.
Maintenance History
Maintenance records indicated that on January 11, 2010, the tail rotor pitch change spider bearing was replaced because it was a service life limited item. The bearing installation procedure required removal of the tail rotor assembly, which involved removing the pitch change links. After maintenance, the helicopter was test flown and approved for return to service on January 16, 2010. It was not operated in revenue service on January 17, 2010. On the accident date, the helicopter was operated for a total of 4 flights lasting 39 minutes, including the accident flight.
One mechanic reported that on January 11, he noticed unusual play on one tail rotor pitch change link. He secured that pitch link (which he had previously removed from the tail rotor blade) by tightening the hardware to avoid losing parts, then removed the tail rotor assembly and briefed other maintenance personnel. The following day, the tail rotor assembly was installed. Another mechanic inspected the pitch change links at the tail rotor pitch change spider and confirmed both were secure with cotter pins; he also inspected the tail rotor through bolt but did not check the security of the pitch links at the tail rotor blades.
Examination Findings
Detailed examination of the tail rotor assembly by the National Transportation Safety Board's (NTSB) Materials Laboratory found no mechanical evidence that the missing bolt that would have secured the pitch change link was properly installed and secured with a cotter pin. The factual report (Materials Laboratory Factual Report No. 10-048) is available in the public docket.
The helicopter was maintained under an FAA Approved Aircraft Inspection Program. At that time, the inspection program did not include, nor was it required to include, specific quality control inspection items following maintenance or repair of critical safety-of-flight items.