Fuel leaks were blamed for the fires, which caused no deaths or injuries, the army said, the Independent reported.
“The army . . . is implementing corrective measures to resolve this issue,” Cynthia Smith, a spokeswoman, said in a statement.
She said the Chinooks would be grounded “out of an abundance of caution until those corrective actions are complete”.
Boeing — and Honeywell, which makes the engines — did not immediately respond to requests for comment.
More than 950 Chinook variants are in service worldwide, according to the planemaker’s website. The US army operates 400 of those.
The Chinook program supports more than 20,000 jobs and 360 suppliers and the helicopters operate in 20 countries.
RHM/PR