Physical wear plays an important role in engine performance and longevity, with the vast number of engines alone indicating the extent of the poten-economic impact. Nevertheless, engine wear is often treated subjectively in terms of understanding the critical wear mechanisms caused by external and internally generated contamination or by the many transients encountered during an engine's duty cycle. In fact, in few other areas of engine design is quantitative data so limited. Consequently, there is a definite need to obtain quantitative, real-time data on engine wear, in general, and to establish correlations between engine wear and inlet air contamination, in particular. This paper discusses laboratory research designed to investigate these concerns.