EASA AD 2021-0171R1
Tail Rotor — Pitch Control Rod Bearing — Inspection / Replacement
Summary
EASA Airworthiness Directive 2021-0171R1 is an updated regulatory requirement addressing inspection and replacement of the tail rotor pitch control rod bearing on Airbus Helicopters SA 365, AS 365, and EC 155 models. This directive mandates inspections of the tail rotor gearbox oil level and magnetic plug, as well as replacement of affected double bearings with improved parts to ensure safe yaw control. It applies to all serial numbers of the specified helicopter models.
What Changed
This revision extends the calendar time limit for replacement of affected tail rotor gearbox parts and updates inspection intervals based on additional testing. It incorporates the latest revision of the applicable Alert Service Bulletin, reflecting reduced inspection intervals and amended corrective action criteria. The directive also clarifies modification requirements and retains previous inspection and replacement mandates.
Why It Matters
Compliance with EASA Airworthiness Directive 2021-0171R1 is critical to prevent loss of tail rotor pitch control, which can lead to loss of yaw control and potential accidents. Operators and maintenance organizations must adhere to the updated inspection intervals and replacement schedules to maintain airworthiness and ensure flight safety. The directive provides clear instructions to detect and correct bearing damage before it compromises helicopter control.
What To Do
Operators of affected Airbus Helicopters SA 365, AS 365, and EC 155 models must perform required modifications within 50 flight hours or 3 months after 2 August 2021 if not already done. They must conduct repetitive inspections of the tail rotor gearbox oil level and magnetic plug at specified intervals and replace the double bearing with improved parts within defined compliance times. Full replacement of the affected tail rotor gearbox with a serviceable part is required within 89 months after 2 August 2021.