The U.S. Army has grounded its entire fleet of 442 Boeing CH-47 Chinook tandem rotor helicopters fitted with dual Honeywell T55 engines after a “handful” of fuel leak-induced engine fires. They are believed to be linked to the installation of non-Honeywell, nonstandard O-rings in approximately 70 aircraft.
The fires have not resulted in any injuries or deaths. The maintenance was performed at an unidentified Army maintenance depot. Honeywell said on Tuesday night that it is working with the Army to identify the suspect O-rings in the impacted aircraft.
"It is believed these suspect O-rings have been identified and isolated," Honeywell said in a written statement. "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 Army has been flying the Chinook for more than 60 years and it is operating in 22 countries. The aircraft made its first flight in 1961 and 13 variants and more than 1,200 have been produced. The Army plans to keep flying the aircraft past 2060, more than 100 years after it was first introduced.
It was immediately unclear as to how long the grounding would last or what specific corrective actions were being taken.