FAA Releases Airworthiness Concern Sheet Over Vibrations for Bell 206L Models

The FAA has released an Airworthiness Concern Sheet (ACS) for Bell Textron Canada Limited Models 206L, 206L-1, 206L-3, and 206L-4. The ACS is a result of reports received by the FAA of severe vertical vibrations on Bell 206L helicopters. These events are inconsistent in their repeatability and post-flight inspections have not identified any failure that caused the vibration event.

The FAA is interested in receiving any information on occurrences of in-flight abnormal vertical vibrations and the conditions/configurations of the rotorcraft at the time of the event. Requested information includes configuration of the aircraft, flight conditions during the vibration event, date of the vibration event, actions performed by the pilot in response to the event, and any findings after the event. See the ACS for full details.

An ACS is neither regulatory nor mandatory. It requests feedback from the aviation industry on a voluntary basis and is intended to increase communications between the FAA and the aviation industry so that input from industry can be used to inform FAA’s analysis of the safety issue. For this ACS, FAA has not yet decided if a corrective action will be necessary or what it might be, but it could involve an Airworthiness Directive (AD) or a Special Airworthiness Information Bulletin (SAIB). The FAA’s final determination will depend in part on the information received in response to this ACS.