U.S. Air Force: Reinventing the Wheel out of Necessity - How a Small USAF Team is Implementing Engineering Authority for the A-10 Warthog

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The information below was gathered from the 2018 Simcenter Conference - Americas that took place October 15-17 in Detroit, Michigan.


Author: Lawrence "Charlie" Stoker, Aerospace Engineer  


The A-10 Original Equipment Manufacturer (OEM), Fairchild, transitioned out of the A-10 business with personnel and data rights transferring to Grumman (now Northrop Grumman Corporation).  Simultaneously, the USAF experimented with multiple sustainment strategies that complicated effective system management and diluted USAF organic engineering expertise.  The impact was far reaching with the effects not being immediately identified.  One element of this was the Aircraft Structural Integrity Program (ASIP) that began rebuilding in 2003.  Over the past 15 years, A-10 ASIP was rebuilt with a holistic approach to structural integrity transitioning from recreated pen and paper analyses based on 1970s analytical methods to modern Computer Aided Engineering (CAE) techniques spanning the collection and presentation of maintenance data through detailed stress and fracture mechanics analyses.  The repertoire still includes classical analysis techniques while taking advantage of Computer Aided Design (CAD), Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD), integrated Damage Tolerance Analysis (DTA), and risk-based fleet management through the integration of Individual Aircraft Tracking (IAT) data with detailed maintenance data.  This allows the development of maintenance intervals based on usage severity and individual aircraft inspection history.  Beyond immediate structural analysis work, the team has also been involved with numerous full scale, component, and coupon tests to characterize both material and processing behaviors.  Due to the breadth of supporting information necessary to maintain structural integrity, the team has also been heavily involved in updating the Product Lifecycle Management (PLM) philosophy.  This presentation will cover the synergy of these disciplines and how the A-10 Structures community is working towards a unified workflow incorporating all pertinent engineering disciplines to a final product, but also how reaching back to classical analyses and matching them is of utmost importance.  Specifically, the workflow involved with transitioning the global CFD pressures to FEA loads application to crack tip stress intensity factor extraction supporting the DTA process will be covered.