East Coast Sea Kings set to retire, but replacements face growing pains

Canada's half-century-old Sea King helicopters will take astep closer toretirement next month, with the last official East Coast flight planned for Jan. 26,CBC News has learned.

West Coast operations will continue until December 2018, military officials said, at which point thenew Cyclone aircraft will officially take over as Canada's Maritime helicopter.

There still may be some Sea King flights on the East Coast past January, but only for logisticalreasons, such as repositioningthe aircraft locallyor sending themto other parts of the country.

Sea Kings have been operating in Canada since 1963.

The multipurposeworkhorse aircraft is paired with every Royal Canadian Navy frigate. Its tail and rotors fold so it fits inside the ship. Its hull is designed to perform emergency water landings, and it can be outfitted as a submarine hunter, with sonar systemsand torpedoes.

Cyclone helicopters still being tweaked

The Sea King's replacement is the Cyclone, a military variant of the Sikorsky S-92.

The federal government has accepteddelivery of more than a dozen Cyclone aircraft, but not all of them are currently in Canada.

Each new batch of helicoptersis flown andtested by Canadian aircraft experts. If changes are needed, the helicopters are sent back to Sikorsky to re-enter the production cycle and the improvements are madefor future versions.

There have been at least three different batches or "blocks" delivered to Canada.

New issue discovered

The navy recently discovered a new problem with the latest block of Cyclones.

Just like the Sea Kings, these helicopters are designed to land on ships at sea. To test the Cyclone's limits, the crew of HMCS Montreal spent months seekingthe worst weather and highest seas.

In extreme conditions, the Cyclonecan use a cable tosafelyland on a ship. While the helicopter hovers above the surging and tilting vessel, the cable slowly winches the aircraft down.

The methodis highly effective, but officialsfound itcan cause problems for another important system.

The Cyclone isalso equipped with asonar system that itlowersinto the water on a tether. It dips beneath the surface and sends out pings to search for submarines.

Sonar could hit ship during landings

"Analyseshave shown that, in theory, it is possible for the sonar submersible unit to contact the ship-mounted assisted-recovery system when operating in high sea state condition," said an emailed statement from Department of National Defence officials.

Put simply, both the sonar and landingsystems work fine.But due to thesonar's position, it could hitthe ship when the helicopter uses the cable landing system.

The long-term fix will be to reposition the sonar system. Until Sikorsky makes that change, the current group of helicopters can either be used as shore-based aircraft, or have the sonar systemremoved for ship-based operations.

Even without the tethered sonar system, the Cyclone can still search beneath the surface. An additionalsonar systemsendsremote buoys into the ocean thattransmit acoustic information wirelesslyback to the helicopter.

The next block of Cyclones will fix the sonar issue by repositioning the mechanism. That block should be delivered by June 2018.