Nearly 60% of the Army’s CH-47 Chinook helicopter fleet have been cleared to operate in training and missions, according to a statement from the service.
The return to duty comes after the Army announced in August that its entire fleet of Chinooks was grounded “out of an abundance of caution.” The move came after an undisclosed number of engine fires took place, which first was reported by the Wall Street Journal.
“Though the number could fluctuate day to day, this number continues to increase daily with ongoing logbook records review and a standard leak-check maintenance procedure outlined in an Aviation Safety Action Message published on 2 September,” Jason Waggoner, a spokesperson for the Army, said in a statement.
In a statement to Army Times after the news of the engine fires first broke, a spokesperson for the service said the engine fires could be attributed to fuel leaks, and the Army had identified the problem with the leaks and had already started to solve the issue.
Honeywell International, which manufactures the specific engine for the CH-47 Chinook, released a statement following the announcement that the fleet was being grounded. The company said that O-rings not produced by the company were to blame for the fuel leakages that turned into engine fires.
“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,” a statement from Honeywell said. “It is believed these suspect O-Rings have been identified and isolated.”
At least 70 of the service’s 400 Chinooks had the faulty O-ring, the report from the Wall Street Journal said.
Zamone “Z” Perez is an editorial fellow at Defense News and Military Times. He previously worked at Foreign Policy and Ufahamu Africa, where he helped produce podcasts. He is a graduate of Northwestern University, where he researched humanitarian intervention and atrocity prevention in his thesis. He can be found on Twitter @zamoneperez.