The objective of this project was to qualify and transition NAVSOLVE™, an environmentally compliant non aqueous cleaner, for the efficient removal of hydraulic fluid, heavy grease, and other contaminates from Department of Defense (DoD) aircraft composite structures. Existing compliant solvents are ineffective and, at best, inefficient at removing these contaminants. Hydraulic fluid ingress into honeycomb core often precludes repairs of composite structure resulting in high part scrap rates. Declining budgets, high costs for composite structure, inconsistent availability of spare parts, and environmental regulations restricting the use of more effective high volatile organic compound (VOC)/hazardous air pollutant (HAP) solvents severely impact DoD aircraft platforms which are incorporating a greater percentage of these light weight structural materials.
To meet emerging environmental regulations, the Aerospace Materials Division at Naval Air Warfare Center Patuxent River developed NAVSOLVE™, a low VOC, HAP-free cleaner that meets the performance requirements of MIL-PRF-32295B Type I and Type II for aircraft structural and engine metal components. This project extended that work by evaluating the compatibility of NAVSOLVE™ with the polymer matrix composites, adhesives, sealants, paints, and core materials individually and as assembled in a structure for use on DoD aircraft. The effort validated successful NAVSOLVE™ substitution for current hazardous solvents in approved DoD cleaning and repair procedures through end user site demonstrations. To support transition, the project also established a new MIL specification, MIL-PRF-32597- “Cleaner, Polymer and Polymer Matrix Composite (PMC) Material, Non-Aqueous, HAP-Free” approving NAVSOLVE™ for use on aircraft composites.
Coupon-level testing verified that long-term exposure to NAVSOLVE™ did not degrade the mechanical properties and/or repair capability of composites or the adhesives and core materials used for fabrication and repair of structures. Site demonstrations validated the ability of the NAVSOLVE™ cleaner to be successfully substituted for current solvents called out in the respective depot composite repair procedures/local process specifications. No additional equipment or materials are required for implementation of NAVSOLVE™ to the composite shops in the Services’ aircraft maintenance facilities. The cleaner has been qualified to MIL-PRF-32295B and the new MIL-PRF-32597 specifications.
Savings are realized not only through reduced costs of hazardous waste disposal associated with current solvents, but through an increased ability to clean and repair contaminated composite parts resulting in reduced scrap rates and their associated disposal/replacement costs. Use of NAVSOLVE™ permits compliance with current and emerging federal, state, and local government regulations on solvents, improves mission readiness by reducing aircraft downtime for repair/replacement of parts, and reduces the environmental footprint of scrapped composite parts due to failed bonded repairs that are currently buried in landfills.