Tail Rotor Abrasion Strips Could Cause Rotor Failure

On March 29, 2024, the FAA issued an emergency AD for owners and operators of Bell 429 helicopters.

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The directive, AD 2024-07-51, was prompted by multiple reports of tail rotor blade abrasion strip cracks, which could lead to severe imbalance, tail rotor blade failure, loss of the tail rotor gearbox, and ultimately, loss of control of the helicopter. The FAA's action follows a similar emergency AD issued by Transport Canada.

An investigation revealed a manufacturing defect in certain serial-numbered tail rotor blades, part number 429-016-101-105, which could result in fatigue cracking due to missed fabrication steps in the abrasion strip.The FAA reviewed Bel Alert Service Bulletin 429-24-63, dated March 21, 2024, which specifies procedures for cleaning the tail rotor blade abrasion strip and using a bright light to visually inspect each side of the T/R blade for a chordwise crack.

The emergency AD requires operators to inspect the tail rotor blade abrasion strips within three days or prior to the second flight after the effective date of the directive. If a crack is found, the blade must be replaced before further flight. If no cracks are detected, the blade must be marked with an "X" using a paint marker. Thereafter, pilots must visually check the abrasion strips for cracks before each flight, and maintenance personnel must perform more thorough inspections every 25 flight hours.

The FAA considers this emergency AD an interim action and may consider further rulemaking if a final action is identified. The directive is effective immediately upon receipt due to the critical nature of the affected components and the potential for catastrophic failure. Operators are required to report any findings of cracked abrasion strips to the FAA within 7 days to aid in further investigation and corrective actions.

FMI: regulations.gov