RCM was first described in the 1978 Nolan and Heap report for United Airlines—Reliability Centered Maintenance1 and subsequently popularised by the late John Moubray in his RCM II books2. RCM was intended by Nolan and Heap for the development of aircraft scheduled maintenance programs based on safety and operational risk control reasons for a maintenance activity. The first paragraph from the Preface of their RCM report says: