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. 

REMEMBERING OUR 13 FALLEN HEROES ONE YEAR AFTER BIDEN ADMINISTRATION’S DISASTROUS AFGHANISTAN WITHDRAWAL

CH-47 Chinook helicopter

Alaska Army National Guard soldiers use a CH-47 Chinook helicopter to removed an abandoned bus. The Army has grounded the helicopter following a series of engine fires.  (AP)

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. In a statement to Fox Business, Honeywell said it has partnered with the Army to investigate the incidents. 

"In full coordination with the U.S. Army, Honeywell helped discover that O-rings not meeting Honeywell design specifications had been installed in some T55 engines during routine and scheduled maintenance at an Army Depot. It is believed these suspect O-Rings have been identified and isolated," the statement said. "The U.S. Army and Honeywell were able to validate that none of the questionable O-rings originated or were part of any Honeywell production or Honeywell-overhauled engines."

"Joint U.S. Army and Honeywell engineers identified the issue, and are now working with the Army to provide replacement O-rings on all affected Chinooks," the statement continued. "Honeywell has been committed to supporting U.S. Army Aviation and the Army’s service men and women for more than 60 years, and that commitment will not waver."

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.

CLICK HERE TO GET THE FOX NEWS APP

Fox News has reached out to the Army for comment.