Main Rotor Drive — Main Gearbox / Magnetic Plug and Oil Filter / Planet Gears — Inspection / Modification / Replacement
- Published
- Effective
- Deadline
- Replaces
- 2020-0156
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must perform magnetic plug inspections every 10 flight hours or after the last flight of the day and oil filter inspections every 25 flight hours. Affected magnetic plugs on Group 1 helicopters must be replaced with improved plugs within 110 flight hours or 3 months. All second stage planet gears must be replaced within 300 flight hours or 24 months and subsequently at intervals not exceeding 300 flight hours. Any detected particles during inspections require immediate analysis and corrective action before further flight.
Summary
EASA Airworthiness Directive 2021-0016 is an airworthiness directive issued by the European Union Aviation Safety Agency affecting Airbus Helicopters SA 365 C1, C2, and C3 models. It addresses inspection, modification, and replacement requirements related to the main rotor drive main gearbox magnetic plug, oil filter, and planet gears. The directive aims to improve detection of planet gear spalling to prevent potential gearbox seizure and loss of helicopter control.
What changed
This directive supersedes EASA AD 2020-0156 and retains its inspection requirements while introducing mandatory replacement of second stage planet gears at reduced intervals. It also requires modification to replace affected magnetic plugs with improved versions and updates inspection intervals for magnetic plugs and oil filters. The directive is considered an interim action pending further regulatory updates.
Why it matters
This directive is critical for operators and maintenance organizations to prevent potential failures in the main gearbox that could lead to catastrophic loss of control. Compliance ensures early detection of planet gear damage through enhanced inspection protocols and timely replacement of vulnerable components. It helps maintain the continuing airworthiness and safety of affected SA 365 helicopters.
More for Airbus Helicopters SA
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- EASA AD 2026-0118Rotors Flight Control – Tail Rotor Actuator – InspectionJun 22, 2026
- EASA AD 2026-0029Tail Rotor Drive — Tail Gear Box Input Flange — Functional ChecksFeb 12, 2026
- EASA PAD 26-017Powerplant — Engine Firewalls — Modification
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