OTTAWA -- Flight investigators have determined the military helicopter that crashed off the coast of Greece in April did not respond as the crew on board expected before going down into the Mediterranean Sea.

The finding was in a preliminary investigation report published Monday by the Royal Canadian Air Force, which did not provide a definitive answer for what caused the April 29 crash.

The report instead says investigators will now focus on both the Cyclone helicopter's various systems and what role "human factors" played in the crash. Military officials have previously said the full investigation could take up to a year.

Six members of the Canadian Armed Forces were on board when the Cyclone helicopter went down while deployed with the Halifax-class frigate HMCS Fredericton. All of them were killed.

The crash occurred shortly after the Cyclone, codenamed Stalker 22, flew past the Fredericton while returning from a routine training mission and conducting some additional training, according to the investigation report.

Officials have confirmed it also participated in a photo-op involving the frigate.

It then turned to set up for landing and, according to the report, "during this final complex manoeuvring turn to close with the ship, the aircraft did not respond as the crew would have anticipated.

"This event occurred at a low altitude, was unrecoverable and the aircraft entered a high energy descent and impacted the water astern the ship."

After the crash, the Air Force temporarily grounded the rest of the military's 17 Cyclone helicopters, which only became operational in 2018 after more than a decade of development challenges.

That "operational pause" will continue until a risk assessment on the fleet can be conducted," Air Force commander Lt.-Gen. Al Meinzinger said in a statement.

"With the co-operation of the directorate of flight safety, a team of airworthiness experts are working closely to develop a plan to methodically and safely return the fleet to operations," he said. "This is critical work and we will take the time to do it right."

This report by The Canadian Press was first published June 8, 2020.