Origins and principles
Nowlan and Heap's reliability-based maintenance method

Around the 1930s, agencies responsible for commercial flight safety, including the US Department of Commerce, began requiring inspections and overhauls to be carried out at fixed intervals for aircraft, engines, equipment and structures.

These practices evolved around 1947, with the advent of after-condition maintenance and the collection of reliability data to implement the actuarial statistical method. Subsequently, the advent of commercial jet aircraft and the impossibility of controlling the reliability of certain equipment led aircraft manufacturers and operators to develop new maintenance concepts. By 1967, it was clear that the accumulated knowledge had to be consolidated, and maintenance techniques developed,...