Pratt & Whitney has asked two airlines to perform early inspections of an engine part used on CSeries planes, a request that comes after a related motor suffered a series of problems that forced some aircraft to make emergency landings.

United Technologies Corp division Pratt & Whitney said in a statement that it added a combustor lining inspection to its regularly scheduled maintenance of the PW1500G engine but declined to comment further.

Bombardier Inc, whose CSeries planes entered service in 2016, said Pratt & Whitney instructed Swiss International Air Lines and airBaltic to inspect engine combustion liners after 2,000 flight hours, Bombardier Commercial Aircraft spokesman Bryan Tucker said.

Bombardier also said Pratt & Whitney were issuing corrected liners that would be on the engine of the first CSeries narrowbody delivered to customer Korean Air Lines Co Ltd this summer, Tucker said. The steel liner fits into the combustion chamber of an engine where fuel is burned.

"We expect the lifespan to be greater than this, but the inspections will determine when the liners require replacement," Tucker said. "The corrected liner's lifespan is expected to be around 6,000 hours and these are expected to be delivered (by Pratt) this summer."

A spokeswoman for Swiss, launch customer for the CSeries, said on Friday that it strictly follows the manufacturer's inspection plans for the engines.

There are no reported performance issues with the PW1500G engine used in the CSeries 110-130 seat jets, unlike a different variant, the PW1100G, which is being used in the A-320NEO.

India's aviation regulator said in February it is investigating technical issues with the engine variant used in Airbus

Group planes flown by IndiGo -- owned by InterGlobe Aviation -- and privately held GoAir.

Two GoAir A320 NEOs made emergency landings following technical issues last month, and in January an IndiGo flight was aborted after one of its engines developed a fault while accelerating for take-off.