EASA AD 2025-0239
Rotors Flight Control — Upper Ball Bearing End of the Main Rotor Servo-Controls — Inspection
Summary
EASA Airworthiness Directive 2025-0239 is an airworthiness directive affecting Airbus Helicopters SA 365, AS 365, and EC 155 models. It mandates inspections of the upper ball bearing end of the main rotor servo-controls to ensure proper nut tightening torque and prevent potential disconnection. The directive applies to all serial numbers of the specified helicopter models.
What Changed
This directive supersedes EASA AD 2024-0110 and introduces additional inspection requirements focusing on the nut tightening torque of the upper ball bearing end of the main rotor servo-controls. It retains previous inspection mandates and adds periodic torque checks after lock-washer replacements, pending certification of a design change.
Why It Matters
The directive addresses a critical safety issue where loss of nut tightening torque could lead to disconnection of the main rotor servo-control, risking loss of helicopter control. Compliance ensures continued airworthiness and operational safety, helping operators and maintenance teams prevent potentially catastrophic failures.
What To Do
Operators must inspect the nut tightening torque of the upper ball bearing end on each main rotor servo-control within 110 flight hours or 6 months after 20 June 2024, and perform follow-up inspections as specified. Any discrepancies require immediate corrective action before next flight and subsequent inspections. Lock-washer replacements trigger additional inspection requirements within specified flight hour limits. Inspection results must be reported to Airbus Helicopters within 7 days.