NTSB: Bell 206L Tail Boom Damage Caused by ‘Aeroelastic Interaction’ | Aviation International News

NTSB: Bell 206L Damage Caused by Aeroelastic Interaction

Helicopter experienced a vertical hop for which the pilot didn’t know the recovery procedure

Damaged tail boom due to vertical hop — This Bell 206L’s tail boom was damaged following a vertical hop encounter. © NTSB

By Matt Thurber • Editor-in-Chief

August 24, 2026

Buckling of a Bell 206L LongRanger’s tail boom during a “vertical hop” oscillation on Sept. 26, 2024, was due to an “aeroelastic interaction between the helicopter’s main rotor blades and nodal beam system, which resulted in oscillations that exceeded the design limits of the tail boom,” according to the NTSB final report. “Contributing to the accident was the failure of the main rotor blade manufacturer to adequately publish the appropriate recovery technique for a known flight dynamics issue.”

The helicopter—N9984K, operated by JL Aviation of Boring, Oregon—was equipped with composite Van Horn Aviation (VHA) main rotor blades, which had replaced the Bell metal blades about five months before the accident. The VHA blades had logged 348.6 hours when the accident occurred. With no passengers and about 135 pounds of fuel, the helicopter was lightly loaded.

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