Air force flight safety investigators say they are looking at "aircraft system and human factors" in their probe of a CH-148 Cyclone helicopter crash off the coast of Greece at the end of April.
The crash killed six military members.
Investigators filed a preliminary flight safety report at the end of May and released a vague public statement today.
That short summary confirmed what had been reported publicly already — that the maritime helicopter was returning to HMCS Fredericton when it passed the frigate and turned around for another "downwind leg" approach to the stern of the ship.
"During this final complex manoeuvring turn to close with the ship, the aircraft did not respond as the crew would have anticipated," said the report.
"This event occurred at a low altitude, was unrecoverable and the aircraft entered a high energy descent and impacted the water astern the ship."
Normally, a flight safety report gives an indication of what caused the crash. This one concludes by saying "the investigation is focusing on aircraft systems and human factors."
In a statement, the Department of National Defence (DND) said that it uses such terminology when "a cause may not be immediately clear."
The officer in charge of flight safety was equally vague.
"There is still a tremendous amount of work to do to understand the exact circumstances that contributed to the accident," said Col. John Alexander. In a separate statement, Alexander also thanked the Cyclone's manufacturer, Sikorsky, for its help in the investigation.
"We remain committed to conducting a thorough investigation to identify all we can that may contribute to safer flying operations," said Alexander.
Flight control issues
Defence Minister Harjit Sajjan has said it could be up to a year or more before a final determination is made on what brought the aircraft down.
The reference to the aircraft not responding the way the crew "would have anticipated" is significant for two reasons.
It points to possible flight control problems that could be either mechanical or computer-related.
The Cyclone is a militarized version of the Sikorsky S-92 helicopter. Unlike the civilian version, the military Cyclone operates on what's known as a fly-by-wire (FWB) system.
Shawn Coyle, a former Canadian air force helicopter test pilot, said he found the decision to install FBW technology on the Cyclones curious, given the fact that the civilian version has a conventional hydro mechanical flight control system with stabilization and autopilot features.
To make the technological leap to fly-by-wire, where computers replace standard hydraulics and cables, is "expensive and took a lot of time to get right," said Coyle, who was also an accident investigator for Transport Canada and the author of several books.
"Someone figured they could convert an analogue system to a digital system and consider all of the issues and failures associated with that."
The 2017 'glitch'
Some of those issues presented themselves as Sikorsky pushed to get the CH-148 into service. During a 2017 training mission off Nova Scotia, one of the helicopters experienced a software "glitch."
The malfunction forced all three flight control computers to shut down and reset momentarily. The aircraft dropped about 500 feet before the pilot was able to recover and reset the system.
The air force said the problem was corrected in a software update through the manufacturer.
Sikorsky won the contract to supply the Cyclones back in 2004 based on the pledge that it could create a military version of the S-92. The result, according to the commander of the 1st Canadian Air Division, was an almost entirely new aircraft.
"The CH-148 Cyclone is a very different machine than the S-92," Maj.-Gen. Alain Pelletier said at a recent briefing.
Delays and cost overruns
"It's not only a militarized version of the S-92 of the helicopter. It's had a number of components, including its mission system — that is the mission, the kit we brought aboard the helicopter to actually support the Royal Canadian Navy."
He called it a "cousin fleet" to the S-92.
The Cyclone's development was beset by delays and ballooning costs as the aircraft had to be certified.
Coyle said there would have been very few people in Canadian regulatory agencies at the time "who would have done certification of [a] fly-by-wire flight control system on a helicopter."
The report released Monday also formally lays out the sequence of events, which inevitably will lead to more public questions about how forthright both the military and the Liberal government were in their initial response to the crash.
In the hours after the accident, DND's only public confirmation of the accident was a statement that the frigate had "lost contact" with the aircraft — a vague acknowledgement that left many believing that the helicopter had gone down some distance from the warship.
In fact, it had crashed in full view of crew members on the flight deck, including the landing signal officer.
Pieces of wreckage and the remains of some of those killed were retrieved recently from the bottom of the Ionian Sea with the help of a U.S. Navy salvage drone.
The Cyclone fleet, which is relatively new and is still being delivered by Sikorsky, has been grounded temporarily — the military calls it an "operational pause". The helicopters will stay on the ground while the investigation continues and a risk assessment is conducted.
Air force commander Lt.-Gen. Al Meinzinger said a team of airworthiness experts is working closely to develop a plan to safely and methodically return the helicopters to active service.
"This is critical work and we will take the time to do it right," he said in a statement.
About the Author
Murray Brewster is senior defence writer for CBC News, based in Ottawa. He has covered the Canadian military and foreign policy from Parliament Hill for over a decade. Among other assignments, he spent a total of 15 months on the ground covering the Afghan war for The Canadian Press. Prior to that, he covered defence issues and politics for CP in Nova Scotia for 11 years and was bureau chief for Standard Broadcast News in Ottawa.
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