The T800-LHT-800 engine has recently completed a successful preliminary flight rating (PFR) development program that led to its selection for go-ahead to final qualification by the Army during a competitive runoff. The T800-LHT-800 is a modern technology 900 kw (1200 HP) class turhoshaft engine intended for application in the Army's advanced rotorcraft LHX vehicle with numerous potential applications to commercial and foreign military installations. At greater than 4:1 power-to-weight ratio, its specific fuel consumption represents a 10 to 30% improvement over current production engines with major steps forward in maintainability, reliability, and sup-portability. The engine is being developed for initial fielding in 1992 by the Light Helicopter Turbine Engine Company, a joint venture partnership of Allison Gas Turbine Division of General Motors Corporation and The Garrett Engine Division of the Allied Signal Aerospace Company.During the PFR phase that ended in September, 1988, significant effort was expended on engine performance development. This program began with a first engine to test that deviated from required part power specific fuel consumption levels by approximately 6.0%. Assets were then methodically applied to diagnose precise areas of deficiency and to develop necessary improvements. From this work, production viable configuration changes were developed which improved the performance beyond specification requirements and provided a significant level of production margin. This program was conducted in a 1.5 year span-within the proper time frame for the start of the final qualification test phase of the program. The lessons learned from this program provide valuable insights into the typical areas where performance deficiencies are most likely to surface in high-technology small engines with aggressive performance goals.