The purpose of this thesis is to demonstrate the feasibility of using a digital computer as an aid in trimming the military, J-79-17, turbojet engine. A computer aided trimming system will enable engine maintenance technicians to assess an engine performance rapidly and to make rotor speed and exhaust gas temperature adjustments which may be necessary to improve the engine performance.

Maintenance data recorded during the trimming of 379 J-79-17 engines have been used in developing a mathematical model of the trimming procedure and of the engine performance. A computer has been programmed and used to prove the trimming algorithm by processing the maintenance data. While this thesis was developed for the J-79-17 engine, a similar algorithm may be developed for other turbojet engines.

The equations developed for this thesis and the trimming algorithm are presented along with the results of processing the maintenance data. A trimming system design layout and a description of the computer software are also presented. The advantages and potential of the computer aided trimming system are discussed.