EASA AD US-2021-04-12: Tail Rotor Drive Shaft Forward Hanger Bearings - Installation / Replacement | RegNotify

Airworthiness DirectiveEASA AD US-2021-04-12

Tail Rotor Drive Shaft Forward Hanger Bearings - Installation / Replacement

Published: Mar 18, 2021
Effective: Apr 12, 2021
Deadline: Apr 12, 2021

Robinson R66

AI-generated summary of the official EASA document. Verify against the PDF before acting.

What to do

Operators of Robinson R66 helicopters with affected tail rotor drive shaft assemblies must install kit KI-235 or replace the assembly with P/N D224-5 within 100 flight hours. They must also remove affected parts from service and avoid installing prohibited parts. Compliance is required by April 12, 2021.

Summary

Federal Register Volume 86, Number 43 (March 8, 2021) is a final rule airworthiness directive issued by the FAA addressing Robinson Helicopter Company Model R66 helicopters. It targets failures in the tail rotor drive shaft forward hanger bearings, requiring installation of a specific kit and removal or replacement of certain tail rotor drive shaft assemblies to mitigate unsafe conditions.

What changed

This new airworthiness directive mandates installing Robinson kit KI-235 and removing affected parts from service or replacing the tail rotor drive shaft assembly part number D224-3 with an upgraded assembly P/N D224-5. It also prohibits installation of certain parts and clarifies applicability to exclude helicopters with P/N D224-4 assemblies installed during production.

Why it matters

This AD is critical for aviation professionals because it addresses a known unsafe condition that could lead to bearing failure and potential tail rotor malfunction, impacting flight safety. Operators and maintenance teams must ensure compliance to prevent bearing overheating and seizure, which could cause in-flight emergencies or damage to the helicopter.

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