This paper analyzes MSG-3 FROM A MANUFACTURER'S PERSPECTIVE and addresses the question: Was it effective? The experience and insights gained from being the first manufacturer in the world to use MSG-3 to develop a scheduled maintenance program for an entire airplane is discussed. Application of MSG-3 to both the 757 & 767 revealed several areas of deficiency which are analyzed as well as the methods used to “work around” them. This discussion of the problem areas is followed by an analysis of the overall effectiveness of MSG-3. A new decision diagram is illustrated and explained which should be considered in developing MSG-4.