AD Proposed for Bell 206L Helicopters with Van Horn Composite Main Rotor Blades

The FAA has proposed to adopt a new airworthiness directive (AD) for all Bell Textron Canada Limited (Bell) Model 206L, 206L-1, 206L-3, and 206L-4 helicopters with Van Horn Aviation main rotor blades (part number 20633000-101) installed under Supplemental Type Certificate (STC) SR02684LA. This proposed AD was prompted by an event in which a Bell 206L with these blades experienced unexpected moderate-to-severe vertical vibration during flight. The pilot landed without further incident, but a post-flight inspection found damage to the tail boom. The root cause of the vibration is still under investigation, and the FAA considers this proposed AD an interim action to address the risk of structural damage and loss of control of the helicopter.

Within 30 days after the effective date of the AD, the proposed AD would require revising the rotorcraft flight manual (RFM) to:

• Insert Van Horn Aviation Rotorcraft Flight Manual Supplement (RFMS) No. 206L-MR-FMS-101, Revision 0, dated March 25, 2026, which specifies procedures to follow in the event of an unexpected moderate-to-severe vibration during flight
• Add the following never-exceed speed (VNE) limitation to the Limitations section: “VNE is 85 KIAS (98 MPH) when gross weight is 3400 lbs. or below, or placarded VNE, whichever is less”

The Van Horn RFMS itself specifies “No Limitations”; the FAA added the VNE limitation based on its risk analysis of historical events and the ongoing investigation. An owner/operator holding at least a private pilot certificate may make the RFM revisions and record compliance in the helicopter’s maintenance records.

You can view the Proposed AD here. Comments are due October 26, 2026.