Original Equipment Manufacturer (hereafter OEM) and Maintenance, Repair and Overhaul providers (hereafter MRO) are making stiff competition for receiving orders in the field of maintenance of large engines of commercial airlines, aiming at expanding their shares. The outline of large engine maintenance work is described below, with the introduction of on-wing engine performance analysis system and new repair technologies (viz. borescope blend repair, powder-feed weld repair and HVOF coating) developed by Mitsubishi Heavy Industries, Ltd. (MHI) as the high-reliability, low-cost and short turn around time (hereafter TAT) as demanded by the commercial airlines.