HALIFAX — Cracks recently detected in most of the Canadian military's Cyclone helicopters could be linked to the aircraft's folding tail mechanism, a military aviation expert said Monday.
Larry McWha, former commander of 423 Maritime Helicopter Squadron at 12 Wing Shearwater in Nova Scotia, says he developed that hypothesis after noting the Cyclone's manufacturer, Sikorsky Aircraft, had not issued any related inspection advisories for the civilian version of the helicopter, known as the S-92.
Unlike the CH-148 Cyclone, the Sikorsky S-92 does not have a folding tail boom, a feature that allows the Cyclone to fit inside the small hangars aboard the Royal Canadian Navy's fleet of Halifax-class frigates.
"It appears to be a problem unique to the Cyclone," McWha said in an interview Monday. "And that leads me to speculate that it has something to do with (the folding tail)."
On Monday, a spokeswoman for the Department of National Defence said it would be premature to respond as the military is still investigating the cause of the cracks and how to repair them. The Royal Canadian Air Force confirmed Sunday it had discovered cracks in the tails of 19 of its 23 Cyclones.
McWha said he checked the websites for Sikorsky and its parent company, Lockheed Martin, as well as those for Transport Canada and the U.S.-based Federal Aviation Administration, but he couldn't find any new inspection advisories for the S-92.
"They act fairly swiftly if these airworthiness authorities believe that there is a common problem," said McWha, a retired Air Force colonel and former Sea King pilot. "They will issue advisories for special inspections .... That has not happened."
Meanwhile, the Air Force has said the maritime helicopters have not been grounded or placed on an operational pause.
As for what is causing the cracking, McWha said it could have something to do with the large hinges and locking mechanism used to attach the tail boom to the main fuselage. The hinges and locks are made from steel, but the boom itself is made from a composite material.
These parts are under tension from aerodynamic forces, vibrations and sudden shocks when the helicopter lands, he said.
"Under stress, the weaker of the two could crack or separate from the stronger material," McWha said. "They are critical. You don't want to have your tail flopping off in flight because something cracked or broke."
The cracks were first detected in one of the maritime helicopters during a routine inspection on Nov. 26 at 443 Maritime Helicopter Squadron in Patricia Bay, B.C. The entire fleet is overseen by 12 Wing Shearwater, which has its own collection of Cyclones.
The military said Sunday that two Cyclones did not appear to have any tail defects, and the remaining two in the fleet were receiving longer-term maintenance and will be inspected at a later date.
Cyclones are typically deployed on board Canadian frigates and used for search and rescue, surveillance and anti-submarine warfare.
On April 29, 2020, a Cyclone carrying six military members crashed off the coast of Greece, killing all aboard. Two internal reviews by the Canadian Armed Forces found the helicopter's autopilot took control of the aircraft as the pilot was turning to land on HMCS Fredericton.
This report by The Canadian Press was first published Dec. 6, 2021.
Michael MacDonald, The Canadian Press