Stepped-extrusions, proven to provide considerable savings and versatile properties in military and commercial airframe structures, can provide similar benefits in the load-carrying structures of business aircraft.
Successful application of stepped-extrusions depends upon utilizing established design criteria for the different sections, developing engineering properties to meet the load/in-service requirements, and obtaining the potential cost savings in the finishing operations.
Business, military, or commercial aircraft, the stepped-extrusion design has the same to offer: product cost savings, versatility, and performance. A stepped-extrusion puts the metal where it is needed minimizing machining, wasting material, and providing optimum versatility in a single extrusion that has different cross-sections. Advantages of stepped-extrusions proven in aircraft such as the DC-9, DC-10, 727, T37, A-4 have been successfully applied to the business aircraft. Stepped-extrusions developed for Cessna Citation wing spars show that application in business aircraft is profitable for tapering sections or assembles where the connecting end is three or four times larger than the longer section.