Air force technicians are being forced to perform more frequent inspections of Canada’s trouble-prone CH-148 Cyclone helicopters after the U.S. manufacturer found a defect related to the main rotor blades, says an internal report.
CBC News has obtained a copy of what’s known as a Record of Airworthiness Risk Management report for the maritime helicopter — basically, the military air safety branch’s plan to manage the aircraft’s critical deficiencies.
The unsigned, undated document says the CH-148’s maker Sikorsky alerted the military on June 6, 2022, to a potential “debonding” problem with the main rotor blades installed on some Cyclones.
Debonding happens during the manufacturing process when moisture gets into the adhesive holding together the thin layers of metal that make up the blade. It leads to microscopic cracks that can cause the blade to rip itself apart under pressure.
In the worst cases of debonding, the skin of the blade peels off while the helicopter is in the air, causing severe vibration and violent shaking that can force the pilot to set down immediately — or even cause the helicopter to crash.
None of the Canadian Forces Cyclone blades have failed in flight.
Sikorsky alerted the military to the problem in June 2022 and provided additional specifics in November 2023 about similar blade failures involving U.S. UH-60 Blackhawks, says the nine-page internal report.
The new information “raises the unmitigated risk level [on the Cyclones] to A-1 — extremely high,” says the airworthiness report, obtained by CBC News.
Concerns about the Cyclone’s main rotor blades surfaced only months after air force technicians repaired vibration-induced cracks in the tails of at least 19 of the maritime helicopters in late 2021 and early 2022.
They also emerged years after a Canadian air force Cyclone crashed into the Ionian Sea on April 29, 2020, killing six members of the military — the biggest single-day loss of life for the Canadian Armed Forces since the Afghan war.
The crash was blamed on a gap in the flight control software that prompted the aircraft to plunge into the sea.
Despite two decades of development, the air force has never given the CH-148 its final operating capability sign-off — an important designation that declares the military got everything it paid for.
Last week, the Department of National Defence (DND) revised its estimate of the lifetime cost of owning and operating the Cyclone to $15.9 billion, including taxes. CBC News reported last week on 2021 internal documents that projected the full life-cycle cost, including purchase, operations and sustainment, was expected to be $14.87 billion.
The latest figures project higher operating and sustainment costs over the decade and a half the aircraft is expected to remain in service.
In a media statement, Sikorsky said inspections found at least four blades on Canadian Forces Cyclones potentially were affected by debonding, while seven other blades which may be compromised are undergoing tests.
“The inspection process is nearly complete and to date Sikorsky has provided four replacement CH-148 blades,” the company said.
DND says suspect blades will be replaced by maker
When the problem was first identified, an initial flight risk assessment concluded in the summer of 2022 that “in total, 19 [main rotor blades]” on Canadian Forces Cyclones are considered suspect, and as many as 10 of the helicopters could be affected.
DND said it expects that all of the suspect blades will be returned to the manufacturer for replacement by the summer.
CBC News showed Defence Minister Bill Blair a copy of the internal airworthiness report during a recent interview. He said it raised important concerns.
“I think my first priority is making sure that the men and women who serve the Canadian Armed Forces can do their job safely and that the equipment that we send them out [in] is fit for purpose,” he said.
Blair said he’s convinced the Cyclones are safe to fly and the air force is managing the issue.
“I rely on the advice we receive from DND and from [Canadian Armed Forces], the people that operate them and also those who are responsible for their maintenance and procurement,” he said.
None of the Canadian Forces Cyclones have encountered a blade failure, according to the report. The air force is, however, pursuing a stepped-up inspection regime that sees technicians conduct “coin-tap tests” on the blades once in every 50 flight hours or three months, whichever comes first.
A coin-tap test allows a technician to evaluate the integrity of a part by tapping it and listen to the resulting tone.
While it’s not common, helicopter blade debonding has been blamed for both civilian and military helicopter crashes over the past three decades.
The Transportation Safety Board of Canada pointed to debonding in its reports on the 2005 crash of a Bell helicopter and the more recent fatal crash in 2019 of a Robinson Helicopter Company R44 Raven near Lac Valtrie, Quebec. Robinson Helicopter disputes that conclusion.
Debonding has also been the subject of airworthiness directives from the U.S. Federal Aviation Administration. It issued a warning in 2015 about Airbus EC225LP helicopters and cited several different models of Eurocopter for potentially defective blades in 2013.
Jeremiah Gertler, a former military aviation analyst for the United States Congress Congressional Research Service, said the main concern for the Canadian air force is how long the required inspections are keeping the Cyclones out of service.
“They should be concerned about this because, with the more frequent inspections, it’s possible that they’ll be able to use the Cyclones less,” said Gertler, now a fellow at the Washington-based Center for Strategic and International Studies.
“They’ll spend less time in the air and more time getting checked out, until there’s a solution.”
Of equal importance to Canadian military planners, he said, is the amount of time it’s taking to get the suspect blades replaced.