Air Force Pulls 1950s Missile Test Kits After Banned-Chemical Finding

A residue found on a 1950s-era device used to test intercontinental ballistic missile communications contained polychlorinated biphenyls, prompting the Air Force to remove the equipment from service and shift crews to modern replacements. Maj. Gen. Colin Connor, commander of 20th Air Force, issued the stop-use order on Aug. 26, 2026, according to an Air Force Global Strike Command announcement.

The affected AN/PRM-10 test oscillator is a signal generator used to examine communications systems associated with the Minuteman III missile. Its removal did not eliminate that testing function: personnel were directed to use a modern replacement that does not contain PCBs. Global Strike Command said the review had not affected either its intercontinental-missile or nuclear-bomber mission.

One confirmed result, six samples still under review

The order followed a routine inspection at F.E. Warren Air Force Base in Wyoming. An airman discovered residue on a component, reported an exposure and received medical attention. The airman returned to duty with no adverse effects, the command said.

Testing confirmed PCBs in residue from one AN/PRM-10 unit. A command-wide inspection, completed within three days, subsequently identified potential residue on six of the eight sets in the inventory. Those additional samples were sent for testing, so the six sets should not be described as confirmed PCB contamination while results remain pending.

That distinction matters for both occupational-health reporting and equipment disposition. The confirmed finding justified isolating the obsolete design, while the potential findings broadened the inspection without predetermining the laboratory results. The stop-use order therefore functions as a precautionary control rather than a declaration that every remaining unit was contaminated.

A maintenance tool can outlive its materials assumptions

The test sets were manufactured from 1952 through 1958, when PCBs were commonly used in electrical equipment. The chemicals offered useful industrial properties, including electrical insulation and resistance to burning, but may cause cancer and other serious health effects. Their U.S. manufacture and importation were banned in 1979.

The episode illustrates a systems-integration issue that extends beyond the missile itself. Long-lived platforms depend on layers of support hardware: diagnostic instruments, fixtures, cables, calibration equipment and maintenance tools. These items can remain operationally useful long after the materials and workplace assumptions under which they were produced have become unacceptable.

Replacing a legacy tester is therefore not simply a matter of discarding an old box. The substitute must preserve the required communications-checking function while fitting established maintenance procedures and safety controls. In this case, the Air Force already had a PCB-free replacement available, allowing the hazardous equipment to be withdrawn without interrupting the underlying testing mission.

That separation between function and hardware is the central readiness benefit. Keeping an obsolete device in service solely because it performs a necessary check can create a conflict between personnel protection and operational continuity. A qualified replacement removes that tradeoff: crews retain the test capability while the legacy units move into a controlled disposal process.

The review now extends beyond eight oscillators

Global Strike Command and 20th Air Force are working with the Minuteman III systems program office to dispose of the AN/PRM-10 kits and identify other test components that could contain PCBs. Disposal is a regulated activity involving controlled handling and documentation, not ordinary surplus disposal, because contaminated materials must be contained and managed appropriately.

The wider inventory review is significant because a 2024 Air Force memorandum documented low-level PCB persistence at missile facilities despite extensive removal work during the 1990s. That history does not establish that other test devices are contaminated, but it supports examining legacy support equipment by age, material composition and condition rather than assuming earlier facility cleanup removed every possible source.

The PCB finding also sits alongside the continuing Missile Community Cancer Study, which has reported higher rates of Hodgkin lymphoma and testicular cancer among personnel around missile bases than among personnel in other career fields. No causal connection between those findings and the oscillator residue has been established. Treating the exposure record, equipment testing and epidemiological work as separate evidence streams is essential to avoid claiming more than the results demonstrate.

The immediate safety action is complete: crews no longer need to use the AN/PRM-10. The unresolved work is broader laboratory results for the six additional samples, controlled disposal of the old kits and identification of any other legacy test components carrying materials that modern maintenance organizations would no longer accept.

By Thomas Caldwell — AMI’s senior editor for mechanical and mobility engineering, covering vehicle electronics, systems integration, electrification, chassis systems, propulsion, and safety policy.