SwRI will be exhibiting at the ASIP Conference, booth no. 1.
Please join us for the following sessions:
Tuesday, Nov. 28
1:30 p.m. – 2:00 p.m.
Session 2: Aircraft Durability & Damage Tolerance I
“Evaluation of T38 DTA Methods,” Teresa Moran
The T-38 ASIP office is striving for their damage tolerance analytical methods to be as thorough, practical and modernized as possible. This is accomplished through periodic reviews of local and industry methods. This presentation will highlight the comparison of the A-10 DTA update (presented by Mr. Jake Warner at ASIP in 2022) methods to the T-38 DTA methods used at present. As the A-10 and T-38 ASIP offices work closely the methodology has developed in tandem. A-10 methodology implemented use of advanced models and changing aspect ratios using AFGROW, T-38 ASIP is evaluating the effect of these methods on their program. Results from the evaluation will be implemented into the next major update of the T-38 DTA. The constant evaluation of analysis will help keep the T-38 flying to the end of the mission life.
Wednesday, Nov. 29
4:00 p.m. – 4:30 p.m.
Session 7: Aircraft Corrosion Prevention & Control
“Triage Structural Integrity Management for the T1A Jayhawk,” Paul Clark
The T-1A aircraft has been utilized by the USAF for training since 1993. It is utilized at multiple US bases primarily to train pilots to fly airlift or tanker aircraft. The T-1A is also used for Combat Systems Officer (CSO) training, exclusively at NAS Pensacola. During routine phase inspections, corrosion was discovered on T-1A aluminum engine pylon ribs. Two occurrences of severe corrosion were found within 5 months during winter/spring of 2022. The severity of the corrosion garnered attention from leadership both at the T-1A Program Office (PO) and AETC. Efforts began to work the challenge and a 180-day inspection TCTO was issued in August 2022. In coordination with the T-1A PO, the Pensacola Corrosion Action Team was formed with an agenda to witness inspection of the first three aircraft and gain a better understanding of the corrosion challenges facing T-1A aircraft stationed at Pensacola. The first three aircraft inspected revealed severe corrosion and were grounded awaiting engineering disposition. Replacement parts would be necessary but were not available; high risk of failure to achieve missions loomed; hesitation to continue inspecting the fleet was high. The engine pylon ribs for the T-1A are classified as primary structure. They are made from 7075-T62 clad aluminum sheet (formed and machined) and surrounded or wrapped on the engine side (outboard) with a 347 stainless steel firewall rib. The corrosion protection between these two different metals is a chemical conversion coating and double coating of zinc chromate primer applied to the aluminum rib. The galvanic couple between the dissimilar metals, the exclusion of faying surface sealant between the components (due to flammability requirements), and the more severe environmental conditions created an opportunistic growth environment for corrosion. The T-1A PO worked with Textron Aviation Defense (T-1A OEM), T-38 engineering, and quality assurance and maintenance personnel at multiple operating bases to formulate a way forward for the T-1A fleet which aimed at ensuring safety and minimizing mission impact. This presentation will describe the challenges faced while working this project; among those being engineering analysis, failure evaluations, improving the previous design, procuring new parts, working with the field to collect detailed and necessary data, and incorporating recurring inspections based on different levels of corrosion severity. It will conclude by describing a solution to maintain mission capability, if by the strand of an exfoliated grain boundary The views expressed in this article are those of the author and coauthors and do not necessarily reflect the official policy or position of the United States Air Force Academy, the Air Force, the Department of Defense, or the U.S. Government.
SwRI is an independent, nonprofit, applied research and development organization that has supported the USAF Aircraft Structural Integrity Program (ASIP) for more than 30 years. Our work in the field spans the entire range of ASIP tasks, including providing in-flight recording of aircraft loads; analyzing static strength, finite element, and damage tolerance of critical locations; and developing inspection and repair options. We provide a complete range of testing, such as detailed metallurgy and fractography, material property tests, and full-scale aircraft static and fatigue tests. We also develop NASGRO®, the most widely used fracture mechanics and fatigue crack growth software in the world, which includes fracture mechanics models for more than 100 different structural configurations. Our array of ASIP engineering services and non-destructive inspection (NDI) development supports all types of aircraft structures.
For more information, please contact Luciano Smith.