Engine diagnostic practices are as old as the gas turbine itself. Monitoring and analysis methods have progressed in sophistication over the past six decades as the gas turbine evolved in form and complexity. While much of what will be presented here may equally apply to both stationary power plants and aeroengines, the emphasis will be on aeropropulsion. Beginning with primarily empirical methods centered on monitoring the mechanical integrity of the machine, the evolution of engine diagnostics has benefited from advances in sensing, electronic monitoring devices, increased fidelity in engine modeling, and analytical methods. The primary motivation in this development is, not surprisingly, cost. The ever increasing cost of fuel, engine prices, spare parts, maintenance, and overhaul all contribute to the cost of an engine over its entire life cycle. Diagnostics can be viewed as a means to mitigate risk in decisions that impact operational integrity. This can have a profound impact on safety, such as in-flight shutdowns (IFSD) for aero applications, (outages for land-based applications) and economic impact caused by unscheduled engine removals (UERs), part life, maintenance and overhaul, and the overall logistics of maintaining an aircraft fleet or power generation plants. This paper will review some of the methods used in the preceding decades to address these issues, their evolution to current practices, and some future trends. While several different monitoring and diagnostic systems will be addressed, the emphasis in this paper will be centered on those dealing with the aerothermodynamic performance of the engine.
A Survey on the Software Technology of Health Management System for Aircraft Gas Turbine Engine
