Following years of doubt due to problems with its 737 MAX passenger jet, U.S. planemaker Boeing has returned to a more “dynamic” production profile, said the head of engine maker and key Boeing supplier Safran on Thursday.

The benchmark narrow-body jet is being made at a rate of almost 38 a month, which is the limit set by U.S. officials after a door plug on an Alaska Airlines plane blew out last year, Safran CEO Olivier Andries said at an annual meeting.

Doug Ackerman, Vice President of Quality for Boeing Commercial Airplanes, told reporters on Tuesday that the company plans to keep making 38 737 MAX planes a month for the next couple of months.

Safran and GE Aerospace work together through their joint company CFM International to make the most popular jet engines in the world. The CFM LEAP engines power all Boeing 737 MAX planes, and they fight with Pratt & Whitney for contracts with airlines to make the Airbus A320neo.

While Safran is positive about Boeing’s progress toward getting jet production back up and running, one of the world’s biggest leasing companies was more cautious earlier on Thursday.

Boeing and Airbus have made progress, but there is “a way to go” to get a stable, regular production cycle, SMBC Aviation Capital CEO Peter Barrett said.

Safran’s Andries told shareholders that demand for repair services for jet engines had risen in part due to delays in production of new aircraft, caused by snags in aerospace supply chains.

Airbus has said CFM is itself one of two suppliers slowing down increases in its output in the first half of the year, while CFM has said it is sure of accelerating in the second quarter. The Airbus and Boeing versions of LEAP are different sizes of engine with a generally different set of parts.

Andries said Safran was meanwhile getting encouraging results from CFM’s wind-tunnel and other tests to demonstrate technology for a successor to the LEAP engine called RISE, designed to cut fuel consumption and emissions by 20%.