You started picking nits saying: There was absolutely nothing wrong with the maintenance procedure. It was simply not executed properly. But the text you cite

You started picking nits saying: There was absolutely nothing wrong with the maintenance procedure. It was simply not executed properly. But the text you cite says: "as a result of the failure of mechanics to follow the established and proper procedures" and "repeated failure of supervisory personnel to require mechanics to comply strictly with the prescribed installation procedures" I'm pointing out that there were, in fact, multiple procedures involved here. Some were well-defined and supported the reliable operation of the engine, some procedures were probably poorly defined and led to rapid failures. But the mechanics do appear to have been following a repeatable process as evidenced by the fact that all the engines failed simultaneously. This is a procedure in the general usage of the term, even if a bad one and different from the one prescribed by the regulatory authorities.