WASHINGTON — The U.S. Army has stopped taking deliveries of AH-64E Apache attack helicopters from Boeing because the service is not confident in the durability of what it deems a “critical safety” item, Defense News has learned.

“We stopped accepting deliveries of new AH-64 Echoes because of a strap pack nut that we believe to be really suspect,” Brig. Gen. Thomas Todd, program executive officer for Army aviation, confirmed to Defense News on April 19.

As part of Army safety inspections of the fleet, the service determined it was “not happy” with the performance of the nuts in severe, coastal environments and saw corrosion due to climate and stress, according to Todd.

The nut in question holds very large bolts that subsequently hold the rotor blades on the helicopter and is therefore determined to be a critical safety item, Todd explained.

While Boeing had already begun a strap pack nut redesign effort six months prior, the Army decided to not take delivery of AH-64 Echo models in February, Todd said, and received guidance from the Army secretary reinforcing the decision. In March, the Army told Boeing it would stop taking receipt of helicopters permanently until the company began fielding a new and improved, acceptable strap pack nut.

It took Boeing and the Army some time to get at exactly what was the root cause of the corrosion and aggressive wear and tear on the nut. But a cause has been identified and the Army has approved a redesign, and Boeing will provide new nuts after testing of the new design beginning in the summer, Todd said.

The company has been working at a “very thorough but expeditious pace over the last six months,” he said. “We are in testing as we speak.”

The Army has estimates that Boeing will be able to field two Apache battalions per month, starting sometime this summer, with the new parts, Todd said. “And we expect them to keep that pace until complete through the entire fleet as well as [Foreign Military Sales] customers that purchase through the U.S. Army,” he added.

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Countries that have bought or ordered AH-64Es are India, Indonesia, Qatar, Saudi Arabia, South Korea and Taiwan.

In fact, Todd said, the Army would push Boeing to do better than two battalions in a month, “so there is every chance that we could accelerate.”

Boeing, in a statement provided to Defense News, said: “Our highest priority is the safety of the warfighter and the reliability of our products. We’re continuing to partner with the Army to address issues, deploying Boeing experts to assist the Army in the field with inspections, and return to the delivery schedule.”

The first units to receive new parts will be those that fly regularly in severe, coastal environments. Todd estimates that is roughly six units in the Army.

There are 653 AH-64s currently fielded. “We are stable there because ultimately we stopped inductions as well because we did not want to hurt the fleet,” Todd said.

Boeing builds an average of six AH-64Es per month in its Mesa, Arizona, facility.

When the Army first fielded the Echo model, it was forced to ground the entire fleet within a month of declaring operational capability following an incident at Joint Base Lewis-McChord, Washington, in December 2013, related to a transmission issue. The service and Boeing resolved the issue in roughly a month.

There have been eight AH-64E mishaps since the Army began fielding the variant in 2013, with five of those considered major accidents involving millions of dollars in damage and/or causing fatalities or major injuries. A crash in 2016 at Fort Campbell, Kentucky, resulted in the loss of both crew members. And earlier this month, also at Fort Campbell, an Apache crashed, killing both soldiers.

While the Apache safety record is not unblemished, the Army’s overall current safety record is steadily improving.

Some (rare) good news for military aviation: Army helicopter accidents on the decline Army aviation's mishap rates are faring far better than the other services in the years following the 2013 Congressional budget cuts.

“We believe, quite frankly, that some of these things that we do, to include stopping production, is the exact type of management that is expected of us and helps us achieve those safety rates,” Todd said.