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Status of Bonded Boron/Epoxy Doublers for Military and Commercial Metallic Aircraft Structures
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English
Abstract
Bonded boron/epoxy doublers are an alternative method vs riveted metal doublers for repair and reinforcement of metallic aircraft structures. They eliminate new holes and provide cost and/or performance advantages for many applications. Over 6,500 boron doublers are flying on military aircraft, mostly in Australia and the U.S.A., and their use is increasing. Commercial aircraft, which are also aging, are beginning to use this technology -- about 230 doublers are flying, either as demonstration “decals”, structural enhancement, or minor repairs.
This paper describes the commercial applications and the major U.S. military ones. The doubler installation process is also described. One documentation of its reliability is the experience on the F-111: no debonds on over 800 doublers in 20 years of use.
This paper also presents the results of an extensive test program sponsored by Textron at Boeing: 110 ultimate tensile strength and 143 fatigue tests of boron/epoxy doublers bonded to 7075-T6 aluminum with simulated cracks.
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Citation
Belason, E., "Status of Bonded Boron/Epoxy Doublers for Military and Commercial Metallic Aircraft Structures," SAE Technical Paper 951145, 1995, https://doi.org/10.4271/951145.Also In
References
- “Composite Repair of Aluminum Structure” Data Updates for Contract F33615-89-C-5643 University of Dayton Research Institute 1992-1993
- Sutherland, W. “Boron Doubler Reinforcement Modification, F-111 Wing Pivot Fittings: Status Report” Sacramento California USAF Air Logistics Center January 1993
- Cochran, J. Hammond, D. “C-141 Composite Material Repairs to Metallic Airframe Components,” USAF SIP Conference December 1992
- Druet, M. “Composite Repair of Metallic Airframe: 20 Years of Experience,” NATO AGARD Meeting on Composite Repair of Military Aircraft Structures Seville, Spain October 1994
- Belason, B Miller, M. Springer, J. et al “Evaluation of Bonded Boron/Epoxy Doublers for Large Commercial Transport Aircraft,” 5th International Conference on Structural Airworthiness of New and Aging Aircraft Hamburg, Germany June 1993
- “Lycoming Sees Fleetwide Potential for Composite Fan Housing Patches,” Aerospace Propulsion March 4 1993
- Belason, B. Miller, M. et al “Evaluation of Bonded Boron/Epoxy Doublers for Commercial Aircraft Aluminum Structures,” FAA/NASA International Symposium “Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance,” Hampton, Virginia, U.S.A. May 1994