Jet engine malfunctions can be detected by acoustic and vibration measurement. A means of detecting engine malfunctions, or functional variations, with a high confidence level is being investigated using digital computer techniques. Operation of the analyzer is based on subjecting incoming “real time” data to predetermined tests and categorizing the data based on these tests. Using this method, several different types of possible malfunctions could be checked at one time in less than 10 sec. Acoustic and vibration designdata, required to form the malfunction decision rule, were tape recorded in test programs of actual known malfunctions in jet engines. Both normal engine data and malfunction data with several degrees of failure were used to establish each predicted-malfunction detection mode. This paper presents the status of this activity.