EASA AD 2020-0146
Main Rotor — Main Rotor Hub — Replacement
Summary
EASA Airworthiness Directive 2020-0146 is an airworthiness directive issued by the European Union Aviation Safety Agency concerning PZL SW-4 helicopters. It addresses the replacement of main rotor hubs (MRH) equipped with specific bearings and inserts that have been found to wear prematurely. The directive applies to all serial numbers of PZL SW-4 helicopters and focuses on ensuring continued safe operation by managing the life limits of affected MRHs.
What Changed
This new airworthiness directive introduces a mandatory replacement requirement for affected main rotor hubs installed on PZL SW-4 helicopters before they exceed 600 flight hours since first installation. It also establishes installation restrictions allowing only serviceable MRHs to be installed, with affected MRHs requiring replacement within the specified flight hour limit. The directive is supported by an Alert Service Bulletin from the manufacturer providing detailed instructions.
Why It Matters
This directive is critical for aviation professionals because it addresses a safety risk related to wear in the bearings of the main rotor hub hydraulic drag damper mountings, which could lead to structural fatigue and reduced helicopter control. Operators and maintenance organizations must comply to prevent potential failures that could compromise flight safety. Compliance ensures continued airworthiness and regulatory adherence for PZL SW-4 helicopter fleets.
What To Do
Operators of PZL SW-4 helicopters must replace any affected main rotor hub before it accumulates 600 flight hours since first installation, following the manufacturer's Alert Service Bulletin instructions. From the effective date, only serviceable MRHs may be installed, and any installed affected MRHs must be replaced within the specified flight hour limit. Compliance with these requirements is mandatory to continue operating the aircraft legally and safely.
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