Military was warned some Cyclone helicopter blades are defective, could rip apart in flight

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