WASHINGTON — The Pentagon's inspector general wants the US Army to address what is perceived by the Defense Department's test community as deficiencies with the howitzer's maximum rate of fire and problems with the automatic fire extinguisher that could potentially endanger the crew.

The DoD's IG determined that the Army's initial production plan to build 133 vehicles as part of the Paladin Integrated Management (PIM) program was sound and effectively managed. Yet, the two issues remain to be resolved, according to a report released Aug. 5.

The PIM program for ground combat consists of ammunition carriers and projectile-firing armored vehicles called howitzers. A howitzer is an armored, tracked vehicle with a cannon and an automatic fire-control system. The program was approved to move into low-rate initial production in 2013 with 33 test vehicles and 100 production vehicles on order.

The Army's total acquisition plan for PIM is 1,112 vehicles. A full-rate production decision will be made in 2017, according to the IG report.

While the howitzers passed the test for sustained rate of fire, it failed the test for maximum rate of fire in 2012 and 2013, according to the IG. "Howitzers failed the test for maximum rate-of-fire in 13 out of 17 attempts during the system development phase tests in 2012 and 2013," the IG wrote. "In 2012, howitzers failed the test for maximum rate-of-fire in all nine attempts."

Program officials then redesigned the hardware and software and revised firing procedures, but still failed a total of four out of eight attempts following the fixes "under non-stressful firing conditions," the report noted.

The test crews didn't test the maximum rate of fire under stressful conditions, it added.

Army Test and Evaluation Command tested the howitzers under stressful and nonstressful conditions, and ATEC reported that they failed to meet maximum rate-of-fire requirements. The reason for this failure is redacted in the report.

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One potential source of the problem is the Fires Center of Excellence (FCoE) did not write a "clear requirement" for the maximum rate, the report said. "Specifically FCoE officials did not identify longer times for stressful firing conditions." The second half of the sentence in the report is redacted.

Some changes to the requirement to differentiate between stressful and nonstressful firing conditions were made in March.

The FCoE commander submitted a request in May to clarify the rate-of-fire requirements for different firing conditions through the Army Capabilities Integration Center. And in June the Army planned to review and approve the requirement change. The revised requirement will be submitted to the Joint Requirements Oversight Council this month, according to the IG report.

The FCoE will continue to reevaluate the maximum rate of fire for howitzers and will test it under stressful firing conditions before the program reaches full-rate initial production, the report noted.

The PIM program also needs to bring in additional Automatic Fire Extinguisher System (AFES) coverage in the howitzer crew compartments, the IG found.

The program officials designed the compartments with just one AFES sensor near the personnel heater, according to the report.

The PIM program was first unable to test the AFES because a production-representative system was not available for testing until 2014, so the service went into low-rate production without the ability to ensure its effectiveness.

ATEC officials then tested AFES on PIM vehicles from August 2014 through May 2015 and "reported that the AFES did not protect the entire howitzer crew compartment during fire survivability testing," according to the IG.

The test community recommended the program find ways to add additional sensor coverage in the compartments.

The program officials "initially disagreed" with the recommendation for additional coverage, stating that the howitzer AFES "functioned as designed" and noted that two portable fire extinguishers were included to add layers of protection, the report said.