Optimal self-diagnosis policy for FADEC of gas turbine engines

FADEC (full authority digital engine control) is widely adopted for gas turbine engine controllers. The advancement of microelectronics produces high speed general purpose programmable logic controllers (PLC) with low price. When they are adopted for FADEC, we can expect high cost performance engine controllers. However, these PLCs were originally developed for ordinary industrial machinery controllers and PLC makers prohibited their use as gas turbine controllers because of their low reliability. Engine makers should give some measures to hold enough reliability when they apply PLCs for FADEC. In this paper, a FADEC is self-diagnosed at the n^th control calculations. Introducing an expected cost until self-diagnosis and an expected cost per unit time, optimal policies which minimize them are discussed. Numerical examples are finally given.