Entire fleet of US Army CH-47 Chinook helicopters grounded over engine fires due to fuel leaks

After an undisclosed number of recent engine fires the US Army has grounded the entirety of its CH-47 Chinook helicopter fleet “out of an abundance of caution.”

After an undisclosed number of recent engine fires the US Army has grounded the entirety of its CH-47 Chinook helicopter fleet “out of an abundance of caution,” the service confirmed on Aug. 30, 2022.

The news to shut down the CH-47 helicopters was first reported by the Wall Street Journal. No deaths or injuries occurred due to the fires.

US Army spokesperson Cynthia Smith attributed the issue to fuel leaks in a statement emailed to Army Times. She said that the service has “identified the root cause” of the leaks and “is implementing corrective measures to resolve this issue.”

The leaks were due to faulty aftermarket O-rings that weren’t produced by engine manufacturer Honeywell International, the company told to Army Times.

“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,” the statement said. “It is believed these suspect O-Rings have been identified and isolated.”

Smith’s statement tried to downplay the scope of the problem, declaring that “some aircraft may not require corrective measures and may soon return to normal flight operations.”

The US Army spokesperson did not specify how many aircraft had caught fire and how many required corrective maintenance. Service officials have identified at least 70 aircraft with the faulty part out of the Army’s approximately 400 Chinooks, the Wall Street Journal reported.

While a joint team of Honeywell and Army engineers identified the engine problem, it’s not clear when they realized they needed to look for it.

An incident where a hovering Chinook had to land and use its fire suppression system to address “a small active fire near the aft portion of the No. 2 engine,” was highlighted in a July aviation safety bulletin published by the service’s Combat Readiness Center.

Smith added that the grounding was meant to “ensure our aircraft remain safe and airworthy.”

The CH-47 Chinook is the US Army’s only heavy-lift cargo helicopter supporting critical combat and non-combat operations.

The CH-47 supports a full spectrum of operations including disaster relief, homeland defense and security, and current overseas contingency operations with a Future Force system design.

The first fully equipped US Army Chinook, designated the CH-47A, entered service in August 1962 with a gross weight of 33,000 pounds (14,969 kilograms).

The current CH-47F is an advanced multimission helicopter with a fully integrated, digital cockpit management system, Common Avionics Architecture Cockpit and advanced cargo-handling capabilities that complement the aircraft’s mission performance and handling characteristics.

The Army Special Operations Command MH-47G combines many proven Chinook systems and features. Notable among these are fuel tanks providing twice the capacity of the CH-47F and an in-flight refueling system. MH-47Gs are remanufactured on the common MH-47G/CH-47F production line.

Photo credit: Acroterion Own work via Wikipedia

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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