Flight control software glitch haunted Cyclone helicopter during trials

The CH-148 Cyclone helicopter haswhat the air force callsa "triple redundant" flight control system and during a 2017 training mission off Nova Scotia, all three of those computers momentarily failed at once.

It was a major software glitch, alarming enough to groundthe fleet for nine weeks.

At the time, the military described the incident publiclyas a "severe bump" which resetthe controls and caused the aircraft to briefly and suddenlylose altitude.The pilot managed to recover and land safely.

One defence expert now says that incident mayprove to be vitally important as investigators probe the cause oflast month'sCyclonecrash in the Ionian Sea. The crash, which happened while the chopperwas taking partin NATO operations, claimed the lives of six Canadian service members four aircrew and two sailors.

Chopper 'flew into the ocean,' say sources

Multiple defence sources tell CBC News thatat the time of the crash, the Cyclone was conducting a high-speed, low-level photo pass of HMCS Fredericton, a manoeuvre known in the air force as a "Brownie Run" after aNATO standard camera.

Without warning, the helicopter suddenlypitched forward and "flew into the ocean," said the sources,who were granted anonymity because of the sensitivity of the investigation.

The March 9, 2017 incident involving asoftware glitch aboard a Cyclone is a matter of public record. What wasn't fully revealed at the time, the sources said, was the fact that all three interconnected computers inexplicably reset themselves something that could have led to a catastrophic crash.

When the grounding of the fleet ended three years ago, the Cyclones continued to operate for a period of time under a series of flight restrictions while their manufacturer, Sikorsky Aircraft, addressed the software issue through a pre-planned upgrade.

Flight restrictions

Those restrictions, among other things, barred the aircraft frompractice manoeuvres close to the ground, sloped landingsand hoisting equipment and personnel.

The limitations were meant to address the pitch and roll of the aircraft and only applied at certain altitudes and in specific flight control modes.

"It's more of a technical restriction and avoiding certain pieces of the code, really, in the software, making sure we don't induce a fault," Col. Peter Allan, commander of 12 Wing Shearwater inNova Scotia, said at the time. (He was quoted in the aviation publication Global Flight.)

"Sikorsky has narrowed down very specifically what pieces of code are affected in the software and how we would induce those pieces of code to be triggered."

A tight timetable

The Cyclone software was upgraded on at least 14 of the 28 Cyclones ordered by the airforce, including the one that crashed off Greece in late April. The work on the aircraft was on a tight timetable because the air force had started to retire the CH-124 Sea King maritime helicopters afterover five decades of service.

The Department of National Defence (DND) was asked recently whether any restricted flight certificates were still outstanding,or if the Cyclones had any limitations imposed on their operations.

"There have not been any additional restrictions added to the fleet following the crash as the investigation is still ongoing,"said Dan LeBouthillier, head of media relations, in an email.

"However, as with every other aircraft in the RCAF inventory, the CH-148 Cyclone is subject to technical limits imposed by the original aircraft manufacturer as well as by operational limits imposed by the RCAF."

LeBouthillier listed some of those technical limits which cover things like theinadvisability of operating the aircraft in climates where the temperature exceeds 47 degrees Celsius, and the proper way to fold its rotors.

An 'operational pause'

DND also refused to say whether the aircraft was observed suddenly pitching forward and accelerating into the ocean.

"As any information of this nature is part of the flight safety investigation, we will not be discussing them publicly in order to ensure the integrity of our investigative efforts," LeBouthillier said.

An "operational pause" was imposed on the entire Cyclone fleet after the crash; essentially, the fleet is grounded againwhile investigators analyze data from the aircraft's twin flight recorders. Last week, Defence Minister Harjit Sajjan said the investigationcould take a yearor more.

Michael Byers, a University of British Columbia defence policy analyst who has written reports and articles critical of the maritime helicopter program, said the software fault could be important if investigators end uprulingout pilot error.

'No time to respond'

Because theaircraft was flying close to the ocean's surface, he said,it would have been in a vulnerable position and the two pilots would have been left withvery little time to react.

"If you are just a few hundred feet above the water, you have no time to respond," he said.

Another question investigators will have to address is whether there were other undetected flaws in the Cyclone's fly-by-wire (FBW) software, Byers said.

"We don't know exactly what happened, but [information to date] suggests a change in the flightcontrol system something went wrong, either a computer problem or perhaps a pilot error, but that seems unlikely," he said.

The federal government and DNDhave an obligation to be more transparent about the accident and the investigation, he added.

DND slow to disclose facts

The first reports of the accident came from local media and Greece. It was NATO not the Canadian government which initially confirmed the aircraft had gone down.

In subsequent public statements, DND downplayedthe notion that the helicopter crashed close to HMCS Fredericton and the fact it happened in front of witnesses was withheld entirely for almost a week after the accident.

"This is about the safety of the aircrew," Byers said. "I cannot see how the Canadian government could withhold information."

The federalgovernment recently wasstill trying to figure out how to recover the wreckage, and the remains of missing crewmembers, fromwater about 3,000 metres deep.

Ceremony honours six Canadian service members killed in crash

4 years ago

Duration 1:59

A repatriation ceremony for six military members killed in a recent helicopter crash was held at CFB Trenton on Wednesday.

The body of Sub-Lt. Abbigail Cowbrough was recovered the day of the crash. Partial remains belonging to Capt. Brenden Ian MacDonaldalso have been retrieved.

Still missing are the remains ofCapt. Kevin Hagen, Master Cpl. Matthew Cousins, Sub-Lt. Matthew Pykeand Capt. Maxime Miron-Morin.

The National Post reported Tuesday that the federal government was in talks with the U.S. about using some of its deep diving technology to retrieve the aircraft.

CBC News asked DND on Monday about the status of the salvage operation. In a statement issued late Tuesday,the department said no decision had been made.