The fault diagnostic process for gas turbine engines can be improved if data acquired by an on-board engine monitoring system (EMS) are utilized effectively. In the commercial transport field, techniques are available to extract engine condition assessment information from steady-state EMS data. In a military environment, steady-state data are not always available, and therefore it is desirable to exact at least some of the information from transient data, such as during take-off. Fault signatures are presented for an F404 engine based on fault implant tests in a sealevel-static (SLS) lest cell. A comparison is then made between the fault coverage capabilities of fault diagnostic techniques based on the use of steady-state engine data with those using transient data. The important conclusions to emerge from this work are that for the range of faults examined, not only is there similar fault information contained within the transient date, but the faults can be detected with increased sensitivity using these data.
