<p class="PARAGRAPH"> <span lang="EN-GB">IEC 61291-5-2:2017(E) applies to optical amplifiers (OAs) and optically amplified, elementary sub-systems for terrestrial applications, using active fibres (optical fibre amplifiers (OFAs)) containing rare-earth dopants, which are commercially available. The black box approach is used in this document. The black box approach is adopted in order to give product specifications which are independent of OA implementation details. For reliability qualification purposes, some information about the internal components is needed; these internal parts are themselves treated as black boxes. This document gives requirements for the evaluation of OA reliability by combining the reliability of such internal black boxes. The object of this document is</span><span lang="EN-GB"> </span><span lang="EN-GB">to specify the minimum list of reliability qualification tests, requirements on failure criteria during testing and on reliability predictions, and give the relevant normative references to establish a standard method for the assessment of the reliability of OFA devices and sub-systems in order to minimize risks and to promote product development and reliability qualification. </span><span lang="EN-GB">This second edition cancels and replaces the first edition published in 2002. It constitutes a technical revision. </span><span lang="EN-GB">This edition includes the following significant technical changes with respect to the previous edition: a) </span><span lang="EN-GB">removal of the contents on the relating quality management system from scope, terms and definitions, and the reliability requirements; b) moving fit-rate calculation to Annex B (informative); c) change of requirements for shock test; d) amendment of abbreviations related to changes a) and b).<o:p></o:p></span> <p class="PARAGRAPH"> <span lang="EN-GB">Keywords: </span><span lang="EN-GB">optical amplifiers (OAs), optical fibre amplifiers (OFAs)<o:p></o:p></span>