Reliability improvement - a plan to achieve and measure reliability of aircraft equipment

ALL procurements and procurement specifications are made with an attempt to obtain equipments that are reliable. The present, classical method of attempting to achieve this is to require that the equipment operate satisfactorily when exposed to a level of environmental stress called for in the governing specification. Usually, these environmental conditions are applied singly, and all are not necessarily applied to any one equipment. While the successful fulfillment of these classical conditions may be necessary, it is not a sufficient condition for equipment reliability. A satisfactory plan for the development of reliable equipment must account for the following: 1. Appraisal of the intereffects of environments on stresses produced and on resultant failures. 2. Measurement of how close equipment strength is to environmental stress; i.e., whether the equipment would fail if the severity of the environment were increased slightly or whether failure would not occur until the severity of the environment were increased many times. 3. Normal variations in the strength of the equipment; i.e., there must be assurance that it was not a random chance that a particular equipment successfully withstood a specific environmental stress. 4. Appraisal of the effects of normal variations of the magnitude of environmental stresses in specific applications.