EASA AD CF-2018-35
Tail Rotor Drive — Tail Rotor Gearbox — Introduction of Attachment Hardware Recurring Torque Check
Summary
Airworthiness Directive CF-2018-35 is issued by Transport Canada and applies to Bell Helicopter Textron Canada Limited model 429 helicopters, serial number 57001 and subsequent. This directive mandates recurring torque checks of the tail rotor gearbox attachment hardware to ensure continued airworthiness and safety. The directive addresses potential loosening of the tail rotor gearbox that could lead to structural damage and loss of helicopter control.
What Changed
This new Airworthiness Directive introduces a repetitive torque check requirement for the tail rotor gearbox attachment hardware during every 200-Hour or 12-Month inspection. It builds on a previous emergency directive by establishing ongoing inspection intervals and procedures to monitor and maintain proper torque levels. Additionally, if any hardware is found loose, more frequent torque checks every 10-25 hours air time are required until stabilization.
Why It Matters
This directive is critical for operators and maintenance organizations to prevent tail rotor gearbox detachment, which poses a serious safety risk including potential loss of control of the helicopter. Compliance ensures structural integrity and operational safety of affected Bell 429 helicopters. It also provides clear maintenance procedures and intervals, aiding compliance teams in meeting regulatory requirements and avoiding operational disruptions.
What To Do
Operators of Bell 429 helicopters must perform a torque check of the tail rotor gearbox attachment hardware within 12 months of the directive's effective date or at the next scheduled 200-Hour or 12-Month inspection, whichever comes first. This torque check must then be repeated at every subsequent 200-Hour or 12-Month inspection. If any hardware is found to move during checks, repeat torque checks every 10-25 hours air time until torque stabilizes, following the specified service bulletin instructions.
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