The Royal Canadian Air Force has grounded its CH-148 Cyclone helicopters after an incident nearly a month ago when one of the choppers "experienced a momentary change in the descent rate," the military disclosed Friday.

"This momentary change self-corrected and the pilot safely landed the aircraft," Capt. Trevor Reid, an air force spokesman, said in an email.

Col. Peter Allan, commander of 12 Wing Shearwater, said during a conference call the crew of the chopper was unable to determine if the change in descent rate was due to a sudden drop.

The incident occurred as the crew was preparing to land after a training flight in the Halifax area.

Company investigating the problem

While the incident happened March 9, the military only disclosed it publicly Friday.

According to Reid's email, a "temporary pause" was ordered March 12 for the fleet while the manufacturer, Sikorsky, works with the director general of the aerospace equipment program management to determine the cause.

A team from Sikorsky is at 12 Wing Shearwater now, investigating the problem with the chopper in question.

Training program delayed

The pause won't affect ongoing air force operations because the Cyclone is still in the trials and acceptance phase, but it will delay the pilot training program for the controversial choppers. Reid said it was the training delay that prompted the decision to disclose what happened.

"We do not know at this point if the pause will have any impact on the overall program or timelines," Reid said in the email, adding the military is confident the Cyclone "will deliver the necessary air power required by the Maritime helicopter community in the years to come."

More helicopters waiting in Florida

The air force has 11 Cyclones, three of which are used for operational testing and evaluation. Two are operated in Shearwater by Sikorsky for training.

The air force is awaiting delivery of four more Cyclones. Two are complete and sitting in Florida at the company's factory, while two others remain in the production phase. The grounding of the fleet here means the two completed helicopters in Florida cannot fly to Canada until further notice.

Positive sea trials

The rollout of the Cyclone program has been long delayed and is several hundred million dollars over budget. The most recent projection for the fleet to be fully in place is 2025. The choppers are meant to replace the fleet of Sea King helicopters.

Reid said recent sea trials for the Cyclone "during various types of weather, including stormy weather with waves reaching 30-feet high," were all positive and met required benchmarks.