Powerplant managers in commercial airlines are under continuous pressure to minimize operating cost. The easiest way to do this, at least for the short term, is believed to be to minimize the cost of each engine repair. Maintenance must be looked upon as a long term investment. Data on JT8D and JT9D engines is presented which supports the hypothesis that spending more per repair will result in a better engine that will run longer between shop visits - reducing the operating costs over the long term. Progress has been made toward substantiating this hypothesis, however, more work is required.
