ARMY AL&T
the benite. Picatinny engineers developed an engineering change proposal to incor- porate the plastic tube into tank cartridge primers in 2011 as a superior design to the lacquer paint.
PREVENTING HAZARDS In addition to the improvements above, an investigation of a 2002 tank fire at Fort Hood, Texas, led Picatinny engineers to discover that tank cartridges were very susceptible to initiation by radio frequen- cies if the primer was in contact with any of the electrodes of the electronics in the tank. Tis discovery necessitated the Army to require primers to be HERO compli- ant. Te radio frequency signals were not the cause of the tank fire, but the radio frequency susceptibility needed correction.
NECESSARY PREPARATIONS
A Soldier assigned to 1st Armored Brigade Combat Team, 1st Cavalry Division carries a 120 mm tank round in December 2020, in preparation for qualification at Grafenwoehr Training Area, Germany. (Photo by Sgt. Thomas Stubblefield, 241st Mobile Public Affairs Detachment)
have catastrophic results in the field if not caught during production. Te high number of critical defects in the design contributed to manufacturing delays because of work stoppage, leading to addi- tional costs and potential defects reaching the field.
Another persistent issue in the production assembly of the thick-walled primer was the application of the lacquer plug resin on the primer body. Te lacquer material would plug the primer body holes (Figure 2), creating a seal and preventing moisture from accumulating inside the primer body to protect the benite (Figure 3). Benite
is a black powder substitute that’s also widely used in wood conditioners. Mois- ture in the primer body would adversely affect the performance of the prim- ers. Te lacquer came off the body holes during handling or transportation many times during primer production, making lacquer inspections a critical inspection item during lot acceptance.
To fix the lacquer issue, the Picatinny engineering team recommended adding a plastic liner design into the HERO primer configuration. Te plastic liner is a tube inserted in the primer body that provides a more effective moisture seal for
Picatinny engineers, with help from the Navy Support Facility Dahlgren, Virginia, which had conducted testing for the inves- tigation, confirmed that the primers were susceptible to radio frequency signals and provided the basis for the Army to issue a safety-of-use message in 2004, titled SOUM-04-020, "Operational, Use of Standard and COTS/NDI UHF Radios." Te safety message said that stan- dard and commercial off-the-shelf UHF radios operating in the range of 200-280 MHz have enough energy to initiate the cartridge primer if the center electrode is touched by either a person or object when within 30 meters of unpackaged tank ammunition. Engineers determined that a primer designed to fire only when exposed to a current of 1.3 amperes or greater would solve the safety problem. Tis value became the threshold require- ment for future primers.
Te Picatinny engineers and Dahlgren test results provided the basis for the U.S. Army’s HERO military standard (MIL-STD), DOD MIL-STD-464, which provides guidance for making all
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