Designing for Maintainability in a Modern Three Spool Fan Engine 700204

The modern turbofan engine has become a very sophisticated machine in an effort to produce the lowest possible cruise fuel consumption. This forces such design configurations as variable geometry or the use of three spools which tend to severely complicate scheduled maintenance and fault isolation.

A new turbofan engine (Fig. 1) now being developed by the Garrett Corp. for executive and commuter aircraft will provide a significant improvement in specific fuel consumption as well as maximum maintainability. The high performance is influenced by the advanced aspect of the engine design. This paper shows that if is possible to use the three-spool configuration to advantage by design innovation to arrive at an engine that can be easily maintained. Furthermore, it has been possible to produce in this design the capability for “on-condition” removal of modules of the engine so that overhaul can be established on the basis of condition rather than on a predetermined TBO (time between overhaul). The manner in which this has been achieved and the significance to the aircraft owner is reviewed.