K. O. Legg, Rowan Technology Group, Libertyville, LA; B. Tufts, QuesTek Innovations LLC, Evanston, IL; D. Tibbitts, General Atomics, Kaysville, UT
Hill AFB is in the process of qualifying for flight a new ultra-high strength corrosion-resistant landing gear steel, designated Ferrium® S53. The steel has essentially the same mechanical properties as standard 300M landing gear steel, yet has significantly higher resistance to general corrosion, impact damage, stress corrosion cracking, hydrogen embrittlement and grind burns. Thus the condemnation rate at overhaul due to any of these causes is expected to be significantly lower, as is the probability of service failure. Lower condemnation and service failure rates represent major potential cost savings. On the other hand the steel is more expensive than 300M. The question is which components can be cost-effectively replaced with Ferrium S53 items, and whether the replacement should be made at overhaul, at condemnation, or (for any component that presents a safety-of-flight risk) across-the-board. Evaluations made for various types of landing gear components will be presented to illustrate the most important cost and performance issues that need to be taken into account in this type of analysis. The analysis is based on the C-MAT life-cycle cost analysis decision tool that was designed specifically for analyzing materials and technology replacements. This decision tool takes into account all the costs of changing technologies, qualifying the alternatives and using them in production, balanced against the savings that may result from lower production cost, smaller inventories, faster turnaround on overhaul, longer overhaul cycles and lower condemnation or failure rates.Work funded by DoD Environmental Security Technology Certification Program.
Summary: Hill AFB is qualifying a new ultra high strength corrosion resistant steel, FerriumŪ S53 for landing gear. The new steel has more resistance to corrosion, stress corrosion cracking, hydrogen embrittlement, grind burns and impact. Adopting it will impose various adoption costs (qualification, drawing changes, etc.) and increase component acquisition cost, but will reduce costs associated with corrosion, including frequent condemnation at overhaul and occasional failure in service. The life cycle costs of making the change are analyzed using the C-MAT life-cycle cost analysis decision tool to choose which items can be cost-effectively replaced and when. Examples of specific component analyses are used to illustrate the most important cost and decision factors.
