Original Date: 10/18/1999
Revision Date: 01/18/2007
Best Practice : F404 Best Build Process
The four rotor assemblies that make up the F404 engine contain several life-limited components which must be replaced before their predefined life cycles expire. Although each component’s life cycle is different, the past practice of reassembling the original components on the rotors during repair and overhaul did not present much of a problem. The main reasons were because the engines were new and the components were in the early stages of their life cycles. However, as the rotors aged, the life cycles also began maturing which caused the rotors to be frequently returned to the Depots for component replacement. Realizing that it needed a process to ensure the maximum service life of repaired rotors, Orenda Turbines introduced the F404 Best Build process in 1996.
Orenda Turbines developed the Best Build process by creating a computer-based process that took advantage of the company’s Equipment Condition Monitoring System, an existing database used since the mid-1980s. The Best Build process matches individual components (based on remaining service life) from the rotor assemblies currently undergoing repairs. Each match is based on real-life data of the component’s life cycle. Using an interactive process, the program selects a combination of parts and conducts a calculation for each combination of components to determine how many times the rotor assembly will have to be returned before all of the life cycled components need replacing. Once the program selects the best combination of components for each rotor, a build sheet describing each component is generated and the specified components are removed from the database inventory. The program also determines the value of the throwaway lives of parts which have not yet exhausted their life cycles.
Orenda’s Best Build process has proven to be beneficial to the Canadian Forces, which rates its field maintenance facilities on their ability to build and repair engines that can remain in service for the maximum number of hours. Since implementing its process, Orenda Turbines now builds all rotor assemblies for the Canadian Forces’ maintenance facilities with the maximum life cycle parts available. As a result, the company can ensure extended service hours as well as reduce the number of acceptable life cycle parts discarded.
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