The U.S. Federal Aviation Administration (FAA) says it has received reports of “severe vertical vibrations” on Bell 206L LongRanger helicopters, and is calling on operators of the type to report any such activity and the conditions surrounding it.
The announcement — contained within an Airworthiness Concern Sheet — came two days before the National Transportation Safety Board (NTSB) released its preliminary report into the fatal mid-flight break up of a Bell 206L during an aerial tourism flight in New York City. Within that report, the NTSB said witnesses heard several loud “bangs” before the aircraft broke into three major sections.
While the FAA’s Airworthiness Concern Sheet makes no mention of the New York crash, it says the agency is aware of “at least one event” where continued vibration in a LongRanger resulted in substantial damage to the helicopter’s tail boom.
That incident took place in Fern Prairie, Washington, in September last year. The NTSB’s prelimary report into the Fern Prairie event says the pilot experienced “a severe vertical hop” while in cruise flight about 1,000 feet above ground level, and the aircraft began to shake violently.
The shaking subsided after the pilot began an emergency descent, and the aircraft landed safely. After getting out of the aircraft, the pilot saw the tail boom had suffered “substantial damage.”
The FAA’s Airworthiness Concern sheet says the reports of vertical vibrations on Bell 206Ls are “inconsistent in their repeatability,” and that post-flight inspections have not identified any failure that caused them.
“Reports indicate the vibration subsides once additional load is applied on the main rotor by increasing collective,” the Airworthiness Concern Sheet states. “The vibration may worsen with a low friction set on the collective.”
The information the FAA is requesting from those who experience the vibration includes the configuration of the aircraft, the flight conditions during the event, actions taken by the pilot in response, and any findings afterwards that may have resulted from or attributed to the vibration.
The agency is asking for responses by Aug. 4, 2025, and said its final decision on any action — which could include an Airworthiness Directive or Special Airworthiness Information Bulletin — will depend in part on the information it receives.
