F.E. WARREN AIR FORCE BASE, Wyoming — The U.S. Air Force Global Strike Command has ordered units to stop using the AN/PRM-10 test oscillator set after polychlorinated biphenyls (PCBs) were confirmed in residue found on one unit and potential residue was identified on several others.
The AN/PRM-10 is a legacy test device used to examine communications systems supporting the U.S. intercontinental ballistic missile (ICBM) force, including the Minuteman III system.
Residue discovered at F.E. Warren
The action follows an incident earlier in August at F.E. Warren Air Force Base in Wyoming. During a routine inspection, an Airman discovered residue on a component of an AN/PRM-10 kit and was exposed to the material.
The Airman reported the incident, received medical attention and returned to duty without experiencing adverse effects, according to Air Force Global Strike Command.
Laboratory testing of the residue confirmed the presence of PCBs. The Air Force said PCBs were commonly used in electrical devices during the period when equipment was developed to maintain the Minuteman III ICBM system.
PCBs are a group of synthetic chemicals that were widely used in electrical and industrial applications because of their durability and other useful properties. U.S. production of PCBs was banned in 1979. Their presence in some older equipment remains a concern because of their known health risks.
Inspection finds residue on six systems
After the PCB finding was confirmed, the Twentieth Air Force ordered a one-time inspection of all AN/PRM-10 kits across Air Force Global Strike Command.
The inspection was completed within three days and covered the command's entire inventory. Officials found potential residue on six of the eight AN/PRM-10 systems. Samples from those systems have been collected and are being sent for additional testing.
Before the equipment was removed from service, the Air Force had issued updated safety warnings, handling precautions and requirements for personal protective equipment at locations where the legacy testers remained in use.
Following the inspection results, the Twentieth Air Force ordered the immediate suspension of AN/PRM-10 use as a precaution while testing of the additional samples continues.
Modern replacements being introduced
Units are now transitioning from the AN/PRM-10 to modern, PCB-free replacement testers. Air Force Global Strike Command and Twentieth Air Force are also working with the Minuteman III systems program office to properly dispose of the withdrawn equipment.
Officials are also reviewing other pieces of test equipment to determine whether they could contain PCBs.
Maj. Gen. Colin Connor, commander of Twentieth Air Force, said the command considers the health and safety of its personnel a priority.
The Air Force said the suspension of the AN/PRM-10 has not caused any mission impacts. U.S. ICBM forces continue to operate, with the command stating that the force remains safe, secure and effective in protecting the U.S. homeland.
Part of wider missile community safety review
The equipment review is part of broader safety efforts that followed the launch of the Air Force's Missile Community Cancer Study in 2023. The study was established to examine potential environmental and occupational factors affecting personnel associated with the U.S. ICBM mission.
The Air Force has been reviewing the Minuteman III system and associated equipment as part of these efforts to identify and address potential workplace hazards.
Gen. S.L. Davis, commander of Air Force Global Strike Command, said the command would continue to identify issues and take appropriate action.
The immediate focus is now on testing the residue samples collected from the additional AN/PRM-10 systems, disposing of the affected equipment and moving personnel to modern replacement testers.
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