MH-47E Structural Usage Monitoring System (SUMS) Fleet Demonstration Results

This paper is a follow-up to the 1997 SUMS paper presented at the last Virginia Beach Forum which described the design, approach and development of the MH-47E Structural Usage Monitoring System (SUMS). SUMS was specifically designed to address fatigue life limited dynamic system components that have a limited service life based on a Safe Life evaluation of fatigue crack initiation. To meet this requirement, SUMS categorizes aircraft usage into a comprehensive list of flight conditions and aircraft configurations for which measured flight loads are available from flight strain surveys. While SUMS currently applies this information in a Safe Life application, there are other potential applications such as evaluating components that are susceptible to modes of deterioration other than fatigue crack initiation (for instance bearing life) or in other applications such as damage tolerance (fatigue crack growth) analysis. As a result, SUMS can play an important and potentially expanded role within rotorcraft health and usage monitoring. SUMS was designed as a ground-based system for several reasons. First and foremost, it was the Army’s desire, given the opportunity to demonstrate such a system on one of the most advanced and highly utilized special operations platforms, to minimize the impact on daily mission activities. Also, by making SUMS a ground based system, modifications to the aircraft were not required. The advantages to ground processing are: (1) since we have entire time histories, we can perform more efficient filtering techniques to improve the quality of the result; and (2) on-board hardware and software are minimized. The disadvantage to this approach is the increased amount of data storage and processing required post flight. Over time, this disadvantage decreases as the cost of computing goes down as computing power goes up. This paper discusses the results of a SUMS demonstration in the field and a SUMS qualification study. The purpose of the SUMS demonstration was to satisfy that SUMS performs as intended and provides the Army with the information it needs to make maintenance and safety decisions. One of the main objectives was to investigate the existence of a cost benefit for employing MH-47E SUMS in the fleet. This paper will present results from this 12-month demonstration, comparing SUMS results with baseline design information. One of the most interesting aspects affecting component fatigue is engine power cycles. This paper will look at some interesting discoveries and trace Boeing’s evolution of this flight regime. Also presented will be an overview of a SUMS qualification study using previously recorded flight data from aircraft similar to the MH-47E. The paper will touch on cost benefit analysis and conclusions, as well as transition issues. We will close the paper with conclusions regarding this work and where we think SUMS is going.