WASHINGTON -- The Army is scrambling to correct a defect detected in some Excalibur artillery shells first discovered in December 2015, the service said in response to questions from Defense News.
Raytheon is the manufacturer of the Excalibur 155 mm guided artillery shell. The current variant has been in full-rate production since 2014. Excalibur is a popular munition for its range and accuracy and has been used in Afghanistan.
A minor crack was discovered in an Excalibur projectile's high-explosive material inside the warhead during routine stockpile surveillance testing. The problematic projectile was manufactured in 2007, but the Army subsequently found more cracks in newer production munitions as well, according to Audra Calloway, a spokeswoman at Picatinny Arsenal, home of the Excalibur program office.
As a precaution, the Army is using X-ray to screen all of its Excalibur projectiles at one of its ammunition plants in the US and "options are being reviewed" on whether it's feasible to X-ray projectiles deployed with soldiers on the front lines, according to Calloway.
An investigation is ongoing to determine the root cause of the defect, she added. At the same time, corrective actions are being taken to assure future projectiles do not have the same problem.
"The most probable cause is from the loads induced on the High Explosive billet after assembly into the warhead body that results from production process variations," according to Calloway.
The Army said the cracks "so far" have not had an impact on "form, fit, function or safety," Calloway said.
"Extremely large cracks" in the warhead's explosive material can increase the risk of a warhead detonating early during gun firing, she said. "The range of impacts depends on the severity of the premature functioning, but could range from weapon damage to personnel injury or death."
But because the cracks found in the Excalibur munitions thus far have been small, "there likely would have been no problem," if they had been fired, Calloway added.
"However, the size of the crack did exceed the system specifications and would have increased the risk beyond the one-in-a-million norm," she stated.
Calloway noted that no projectile warheads have malfunctioned during any combat, developmental or surveillance activity in either the US or in combat zones.
The X-ray screening and "minor" changes made to avoid cracks in the future will not affect the contract unit cost of the projectile or any new production schedules, she added.
The Navy is considering -- among several options -- the Excalibur munition to replace the Long Range Land-Attack Projectile (LRLAP) that was to be used in the guns of the DDG 1000 Zumwalt-class destroyer because the LRLAP was determined to be too expensive at $800,000 per round or more.