PARIS—MTU Aero Engines believes the aerospace supply chain will continue to be hesitant on agreeing to further rate increases for single-aisle aircraft.

“I don’t see that anyone will be prepared to invest again in a higher rate,” MTU’s head of programs Michael Schreyoegg said at the Paris Air Show June 18. “People are waiting to see what programs come next.”

Airbus had been pushing its suppliers hard to agree to rates beyond the 63 aircraft per month that it now plans to reach in 2021—already a slower ramp-up than the manufacturer would have liked. But Airbus received pushback from engine suppliers and therefore could not pursue its plans as aggressively as it would have liked. Boeing has temporarily cut 737 production to 42 aircraft per month from 52 as it awaits the MAX return to service; the manufacturer was on its way to reach 57 units.

Schreyoegg said engine manufacturers themselves may not be the bottleneck but their suppliers, in particular those suppliers in the much-consolidated castings market.

MTU meanwhile has started work on its share of the next generation geared turbo-fan (GTF) engine that could power a successor of the A320neo or 737 MAX in the mid-2030s. Schreyoegg anticipates that the engine can reach 10-15% lower fuel burn than the current GTF versions—which  power the A220, A320neo, United Aircraft Corporation MC-21, the Mitsubishi M90/100 and the Embraer E2 family.

MTU currently has a share of around 18% in the PW1100G program and has a final assembly line for the type at its headquarter facilities in Munich. The company would like to increase its workshare in the next engine program to 25%.

Pratt and its partners have offered a scaled version of the current GTF engine for Boeing’s proposed new mid-market airplane (NMA). The engine will be rated at around 50,000 lb. should it be chosen.