9MAY - 2023A hybrid solution paves the wayNAVAIR's MIL-PRF 23377 CL N is a hybrid solution in the journey to remove harmful chemicals from the industry. It is, in effect, the `bridge' that starts reducing the use and reliance on chrome and lays the foundation of trust needed to shift to a chrome-free world. That initial step from NAVIAR paved the way for the US Air Force to release MIL-PRF-32239. Senior leaders in the US Air Force committed to moving to chrome-free systems for all their aircraft. Both of these specifications have led to the introduction and development of new coatings, including Aerodur HS 2118, Aerodur 2122, Aerodur 2100 MgRP, and the soon-to-be-launched AkzoNobel MIL-PRF-23377 Class-N primer. MIL-PRF-32239 established the requirement of a chrome-free coating system, consisting of a non-chrome surface treatment, a chrome-free primer, and a highly durable single-stage topcoat for aircraft exteriors. The adoption of this specification within the Air Force has accelerated change. With the release of this new specification, many platforms immediately started evaluating the technologies available, and thanks to the successes already realized within the commercial industry, the Air Force has moved quickly to make chrome coatings a thing of the past.An excellent example of how the Air Force is moving away from chrome is the Boeing-built KC-46 tanker, a military version of the Boeing 767. Combined efforts between The Boeing Company and the Air Force have led to the qualification of Aerodur HS 2118 CF primer from both organizations. The primer not only provides excellent corrosion protection, but it also meets military and commercial aerospace requirements for fluid resistance (including hydraulic fluids) and optimizes the system adhesion of the exterior decorative finish. In this example, Aerodur HS 2118 CF is a technology born out of the commercial aviation space and from which the military is immediately benefiting.Building the FoundationsThe acceptance of chrome-free systems within the industry has not been a short journey nor has it been without its challenges. Like any major change, acceptance takes time, testing, failure, redevelopment, more testing, and proof. AkzoNobel released its first versions of chromate-free exterior primers in the late 1990s and has spent the last 30 years making the technology better. First efforts are rarely the best, but with the release of second, third, and fourth-generation coatings the technology has improved to the point where it is on par with chrome coatings. Aerodur 2100 MgRP, is an example of an earlier generation of a chrome-free primer. When initially released for trial, evaluators were so surprised by the efficacy of its performance, that many doubted the results and had the product re-tested. While its corrosion-inhibiting properties were superb, the product presented application challenges that early adopters were unwilling to accommodate. Chromate primers are non-discriminating during application and will go anywhere and everywhere, which is advantageous. Chrome-free primers, on the other hand, tend to provide protection `locally' and are fairly specific to the pre-treatment, the paint stack, and the substrate they are trying to protect. Painters who had become used to the performance of one coating over another now found themselves with a primer that appeared less forgiving in its application, certainly at the beginning. Now those same painters are more familiar with the product, and its idiosyncrasies, they can optimize their own and the product's performance. This learning curve was necessary for Aerodur 2100 MgRP to gain acceptance. While initially developed for the military, Aerodur 2100 MgRP has found its place in the world of General Aviation. Protected Investment The continued development of new and more robust chrome-free solutions was not hampered by the pandemic. the steep decline of the commercial aviation space is well documented, however, the US Military's mission never changed, and all branches are dedicated to adopting safer and more environmentally friendly alternatives to chromates. Changes in procurement strategy and the guaranteed investment of the U.S. Government are helping organizations commit to the long timelines and investment needed to change the industry. Universities,
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