AFRL materials integrity experts are collaborating with the Aeronautical Systems Center's C-5 Systems Group, Warner Robins Air Logistics Center (WR-ALC), and Air Mobility Command (AMC) in an effort to disassemble and analyze components of an out-of-service C-5A aircraft. Members of the 653rd Combat Logistics Support Squadron at WR-ALC extracted the major components from the aircraft and shipped them to participating laboratories for analysis (see Figure 1). This study is the first of its kind performed on the C-5A, the US Air Force's (AF) largest cargo aircraft. General John W. Handy (USAF, Retired), former AMC commander, requested the study in order to determine if the C-5A's structure and components are fulfilling original design predictions and to evaluate the aircraft's long-term maintenance requirements.
AMC and the C-5 Systems Group are relying on AFRL's expertise to provide the data needed for determining the capabilities of the aircraft in its current state, identifying improvements, and eliminating future C-5A concerns. AFRL has a legacy of providing quick, responsive support relative to a variety of important material evaluation areas, including failure analysis of metallic, composite, and electronic components, as well as nondestructive evaluation of both structural and nonstructural aircraft components. The program's threefold purpose involves (1) analysis of integral aircraft components to assist AMC planners in identifying the magnitude of future fleet component repairs and replacements, (2) identification of unexpected structural integrity concerns, and (3) validation of both the Aircraft Structural Integrity Program process and the fleet structural maintenance plan.
AFRL scientists led the integrated product team (IPT) that developed program requirements for the disassembly, nondestructive evaluation, and metallographic analysis of the selected C-5A components. Multiple subcontractors are performing the various component evaluations, and the IPT-established requirements will ensure standardization of test and data reporting procedures throughout the program.
AFRL materials scientists are also conducting independent audits of several of the subcontractors identified as project participants. These audits will verify each organization's ability to follow procedures and report results that WR-ALC, AMC, and the C-5 Systems Group can use. The scientists will employ a damage tolerance analysis software program to process collected data and enable accurate life-cycle predictions for the aircraft and its components.
The IPT also identified several high-priority components for AFRL in-house evaluation; these components include the inboard engine pylon attachment fitting (see Figure 2), the aft pressure bulkhead, and the contour box beam fitting. AFRL's in-house evaluations will determine each component's fatigue and stress corrosion cracking issues. In addition to investigating those components initially identified, AFRL scientists will evaluate any components subsequently found to require more thorough analysis.
Capt Lewis C. Lietch and Mr. Timothy Anderl (Anteon Corporation), of the Air Force Research Laboratory's Materials and Manufacturing Directorate, wrote this article. For more information, contact TECH CONNECT at (800) 203-6451 or place a request at http://www.afrl.af.mil/techconn_index.asp . Reference document ML-H-05-02.