Rapid Thermoplastic Patching Capability for Legacy Thermoset Airframe Sustainment

SBIR topic DON27BZ02-NV018 (U.S. Department of Defense – Navy), Phase I and II. Open to U.S. small businesses. Opens: December 2, 2026. Closes: January 6, 2027. Current composite airframe repair methodologies rely on a combination of wet-layups, B-staged epoxy prepregs, and bonded pre-cured thermoset patches. While pre-cured patches are the standard for high-quality depot repairs due to their autoclave-consolidated strength and “inspectability”, they present significant operational and logistical limitations. All these traditional methods require secondary adhesive bonding (using paste or film adhesives) to attach the repair to the airframe. This secondary bond is the inherent weak link of the repair, demanding long thermal cure cycles (often 4 to 24 hours), strict environmental controls, and burdensome cold-storage logistics (freezers) for the B-staged resins and adhesives. Furthermore, these out-of-autoclave epoxy repairs often struggle to meet the high service temperature requirements of advanced tactical aircraft. This SBIR topic seeks to evolve the current pre-cured repair methodology by transitioning from secondary adhesive bonding to high-speed fusion welding. The objective is to develop the capability to use pre-consolidated, high-temperature thermoplastic patches (e.g., Carbon/PEEK, Carbon/PEKK) on legacy thermoset aircraft (epoxy/Bismaleimide [BMI]). By replacing the lengthy adhesive cure cycle with a rapid welding process, this technology aims to achieve flight-ready repairs in expeditionary and carrier-based environments in a fraction of the time. Because thermoplastics melt and thermosets do not, achieving a structural weld between these dissimilar materials is the primary barrier to fielding this capability. The Department of War seeks complete thermoplastic patching solutions that incorporate the requisite chemical or mechanical interfacial enablers—such as plasma surface activation, novel chemical tie-layers, or laser-ablated mechanical…