Aircraft Applications for the Controlled Shot Peening Process

Shot peening has been used as a process to improve fatigue life and fatigue strength of metal for centuries. Modern applications began with General Motors Corporation in the 1920's, when they began shot peening valve springs to improve fatigue life. Over the years this process has been applied to a variety of metals to improve fatigue characteristics and with the advent of SEM (Scanning Electron Microscope) technology, failure mechanisms such as SCC (Stress Corrosion Cracking) and IGA (Intergranular Attack) have been identified. Shot Peening has been proven to retard SCC and eliminate IGA. Detailed shot peening specifications have been developed by major aircraft manufacturing companies and many of these practices have been incorporated in the repair and overhaul of operational aircraft. The integration of automated, controlled shot peening into these applications has placed shot peening in the REQUIRED SERVICES category.

It is obvious to those responsible for the safety of operational aircraft, that use of the benefits of such a process as a design element requires an absolute repeatability of the process. For these reasons, families of application specific equipment have been designed and placed in service. Procedures have been developed to eliminate or greatly reduce the possibilities for variations in process results.