Provides guidelines for the planning and performing of reliability tests and the use of statistical methods to analyse test data. Describes the tests related to repaired and non-repaired items together with tests for constant and non-constant failure intensity and constant and non-constant failure rate. The purpose of these tests is to discover weaknesses in the design and to undertake actions to eliminate these weaknesses and thereby improve performance, quality, safety, robustness, reliability and availability and reduce costs.