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The Federal Aviation Administration has issued a final airworthiness directive requiring operators of certain Airbus Helicopters Deutschland GmbH Model MBB-BK 117 D-3 helicopters to inspect their aircraft. The rule addresses a safety issue involving excessive vibrations that were traced back to an incorrectly installed angular ball bearing in the control ring assembly.

Why it matters: This is a safety mandate aimed at preventing potential loss of helicopter control. While the mechanical failure described—wear from a misaligned bearing—is specific, the consequence (reduced control) is serious enough to warrant immediate inspection and correction for affected aircraft in the U.S. fleet.

Who it affects

  • Operators of Airbus Helicopters Deutschland GmbH Model MBB-BK 117 D-3 helicopters

This summary is based on a final rule published by the Transportation Department’s Federal Aviation Administration; you should check the original document at regulations.gov under Docket No. FAA-2025-2540 before relying on it for compliance purposes.

Agency: Transportation Department, Federal Aviation Administration
Source: Federal Register — read the official document

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