ARMY AL&T


“We have literally removed a health risk from the work environment, ultimately removing the risk to our workforce."


break down and it forms more and more and more, until you get to the point where the iron oxide is basically all that’s left.” In other words, unprotected metals break down when exposed to oxygen and moisture.


One particular heavy metal, hexavalent chromium—also known as chromium-6 or chrome six—is used widely in aviation as an anti-corrosive protective layer. “Hexavalent chromium is a corro- sion inhibitor that has been used in processes for over 50 years,” Feathers said. Some of those processes include hard chrome plat- ing, anodizing of aluminum and magnesium—which allows for better primer adhesion—sealants, adhesive bond primers, and as post-treatment sealing for other processes, like cadmium plating, and pretreatment of aluminum. “Coatings interrupt the corro- sion process or minimize its ability to occur,” he said.


AMCOM has been working for more than a decade to miti- gate heavy metals exposure—they specifically began researching hexavalent chromium in 2006. Te organization has always followed Occupational Safety and Health Administration (OSHA) and U.S. Army safety guidelines for permissible exposure limits, Quinn explained. But when the Army adopted the ACGIH (American Conference of Governmental Industrial Hygienists) lower hexavalent chromium exposure limit standard in 2018, this heavy metal’s days became numbered. Te new ACGIH standard is about 10 times more restrictive than the previous OSHA stan- dard, Quinn said.


“We put together a heavy metals working group at AMCOM [in 2018] and we literally tested every single operation that had heavy metal exposure—specifically chrome six—and identified the levels, the risk and what we needed to do to bring those facil- ities into line,” Quinn said. Because AMCOM started working on hexavalent chromium mitigation and replacement more than 10 years ago, it is now meeting the more rigorous 2018 stan- dards, he added. Te Army’s heavy metals working group and those working the Army’s toxic metal reduction program are a large part of that success.


FIRST OF MANY


John Farhat installs wiring for a UH-60L Black Hawk communications system inside the aircraft tail section at the Corpus Christi Army Depot. This is the first aircraft to be painted using 100 percent, chromium six-free Class N primers. (Photo by Ervey Martinez, Corpus Christi Army Depot)


Te Army’s toxic metal reduction program has worked with AMCOM to develop alternatives for hazardous constituents in the products used in aircraft and missile weapon systems depot and field maintenance processes. “We leverage existing technol- ogy or develop new ones” to do so, Feathers said.


One of those new methods is the Class N primer, which does not contain chrome six.


PRIMED To remove heavy metal additives from the fleet, specifically hexavalent chromium, AMCOM must replace the anticorrosive coatings on current aircraft with the newly approved Class N primers.


All heavy metal “alternatives are all put through rigorous test- ing and demonstrations to ensure they will work and can be used safely, before they are approved.” Feathers said. “Alterna- tives must always meet the original performance standards. As


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