Rolls-Royce is not ruling out the possibility that it might partner with another engine manufacturer to power Boeing's New Mid-market Airplane.

The UK manufacturer disclosed today that it had withdrawn from the competition to develop a version of its UltraFan future engine for the proposed aircraft.

Alluding to in-service issues with the Trent 1000 engine, chief executive Warren East said during a financial results briefing that the manufacturer had learned from "bitter experience" that a newly developed engine needed "a certain level of maturity" before employment on an aircraft programme.

As there is "not sufficient overlap" between R-R's existing UltraFan programme and Boeing's NMA specifications, it would not be feasible to develop a new engine with sufficient maturity within the US airframer's timeframe, East says.

However, he says that R-R could become interested in a co-operation with another manufacturer to supply an NMA powerplant, if such an opportunity arose.

This would depend on which manufacturer was selected and whether that company and R-R then saw any merit in a potential partnership.

"We have see what happens," East cautions. But he says: "Of course, we are open."

Boeing has previously said it received NMA engine proposals from GE Aviation, Pratt & Whitney and R-R.