Managing failures of aircraft systems by coapplication of parametric and nonparametric methods

Analysis of failures that occur in an actual operational environment is very important for the maintenance service providers and manufacturers to offer specific maintenance solutions or product improvements tailored to the customers' needs and to survive in the highly competitive aviation market. There are mainly two methodologies for failure analysis: Parametric approach and nonparametric approach. Practitioners usually prefer one of these methodologies alone for monitoring or predicting the failure trends. However, each methodology has its own strengths and weaknesses for any application. Therefore, it may be useful to view these methods as being complementary for obtaining the most benefit from the failure analysis. This paper brings the parametric and nonparametric methodologies together for extracting valuable management information from the field failures of aircraft systems with an example of auxiliary power unit application. Opportunities of coapplication of the methodologies are described for identifying failure trends and unusual behaviors and revealing hidden information that may otherwise not be detected by the application of only one of those methodologies.