Concerned about a series of engine fires, the Army has grounded its entire fleet of CH-47 Chinook helicopters. 

The U.S. Army Materiel Command grounded the fleet of hundreds of helicopters "out of an abundance of caution," The Wall Street Journal reported, but Army officials were looking at more than 70 aircraft that contained a part that could possibly be connected to the problem. 

It was not clear how long the grounding could last but the move could pose logistical issues for the Army as the Chinook has been part of the branch since the 1960s. 

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The Army has about 400 of the helicopters in its fleet. 

People familiar with the matter told the newspaper the grounding was aimed at Boeing Co.-made models with engines made by Honeywell International. 

An Army spokesperson told the Journal the service has identified the cause of fuel leaks that caused a small number of engine fires. The Army is taking steps to address the problem, she told the paper. 

"The safety of our soldiers is the Army’s top priority, and we will ensure our aircraft remain safe and airworthy," the spokeswoman said.

Fox News has reached out to the Army for comment.