The Royal Canadian Air Force and Sikorsky appear no closer to finding the root cause of a failure with a flight control computer that has left its fleet of CH-148 Cyclone maritime patrol helicopters grounded since 10 March.

Sikorsky has delivered 11 Cyclones to the RCAF, with three operating as test and evaluation aircraft. The commander of the Canadian Air Division ordered an "operational pause" with the helicopters after a failure in the flight control computers on one test aircraft caused a momentary, uncommanded pitch change during a 10 March training sortie.

The incident marks yet another hurdle for the Sea King replacement programme, which has faced ballooning costs and technical glitches over its lifetime.

While the incident did not affect core operations, operational test and evaluation has been suspended during the investigation. The air force does not know when the grounding will be lifted and test and evaluation will resume, Ottawa's Department of National Defence (DND) tells FlightGlobal.

“In the meantime, RCAF pilots are doing increased ground training and simulator work, but the temporary flying operations pause will delay the overall pilot training program,” it says. “The extent of that delay, and any subsequent impacts, are not yet known.”

It addition, until the root cause of the fault is identified, it is too early to say if Sikorsky will be liable for any penalty, the DND adds.

Maintenance training on the CH-148 is unaffected, it adds.

The first 11 helicopters comprise the Cyclones’ Block 1 configuration. The RCAF expects Block 2 deliveries to begin next June and wrap up in 2021, with the final fleet of 28 helicopters also scheduled to be complete that year.