Official comments to the proposed consultation paper are to be filed through the EASA Comment-Response Tool (CRT).
Details
Identification of issue
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Purpose and scope
The purpose of this Certification Memorandum is to supplement the existing guidance for compliance with CS 27/29.602 – Critical Parts, detailing the need for post certification actions to verify the continued integrity of critical parts. These actions should ensure that critical parts are controlled throughout their service life in order to maintain the critical characteristics on which certification is based. In addition, the effectiveness of any associated design, maintenance and monitoring provisions, which either help ensure the continued integrity or provide advance indication of impending failure of critical parts, should be assessed.
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Background
Service experience has shown that assumptions made during certification regarding the influence of environmental and operational threats upon critical parts may not always be valid or remain valid throughout the operational life of the product. In addition, the effectiveness of maintenance actions at both component and aircraft level can also be reduced when compared to that expected at the time of certification. To accumulate significant operational experience without verifying the continued integrity of these components could result in extended exposure to unforeseen degraded safety margins. Accordingly, this CM is intended to propose a process for review of certification assumptions relating to critical parts, including the effectiveness of design, maintenance and monitoring provisions, periodically throughout the life of the helicopter type.