Graphical Techniques for Managing Field Failures of Aircraft Systems and Components

This paper presents an application of graphical techniques based on cumulative and mean cumulative function plots for extracting management information from field failures of aircraft systems. Monitoring field failures is very important for aircraft operators who carry out in-house maintenance as well as for companies who provide maintenance services to the operators on a contractual basis. Very valuable information can be obtained from field failure analysis which will aid in tailoring the maintenance services in accordance with the operator's own local deployment, environmental and operating conditions. Analysis based on field failures is also very desirable for manufacturers, because the information received from the field gives a true measure of product performance and points out the areas of improvement to refine the product by design changes. Reliability practitioners usually attempt to analyze failures of aircraft systems with sophisticated statistical methods. Management and engineers who maintain and support the systems are easily intimidated by such intricate methods. Monitoring the failure of aircraft systems does not necessarily require complicated methods. This paper indicates a few simple but very powerful plots that help in tracking field failures of aircraft systems with an example of an air cooling system application. The plots based on mean cumulative function allow for measuring and monitoring system failures and maintaining statistical rigor without resorting to complex stochastic techniques. It is easily understandable by management and engineers, and enables them to quickly identify failure trends and unusual behaviors, compare different subsets of systems, reveal hidden information and gain insight.