Boeing said Friday that it has resumed “some 737 Max flight activities,” roughly a week after grounding the fleet due to a potential problem with some of its CFM Leap-1B engines. The company added that regulatory authorities support the decision to resume flying and reiterated that delivery of the first production example will occur this month.
Earlier in the day the U.S. Federal Aviation Administration said it was working with Boeing and engine maker CFM International on a plan to clear the 737 Max to return to flight testing. Boeing suspended 737 Max test flights “out of an abundance of caution” on May 5, after CFM notified it of a potential “quality escape” involving low-pressure turbine discs in certain Leap-1Bs delivered to the airframer.

In a statement issued Wednesday, Boeing said it was working with CFM to inspect the discs, the problem with which CFM and its supplier discovered as part of its quality inspection process. Boeing added that it had “at no time” experienced any problems associated with the Safran-supplied low pressure turbine during flight testing. A Boeing spokesman told AIN that CFM notified the airframer of the possible defect late last week and that it took immediate action.

“We will work closely with CFM to understand the precise scope and root cause of the quality issue,” said the Boeing statement. “Our plan remains to begin Max deliveries in May. Max production will continue, as will production and delivery of our Next-Generation 737 airplanes.”

The Max program has so far clocked 2,000 hours on the engines, including abuse testing and flights lasting more than nine hours. Boeing’s inspections throughout the process hadn’t uncovered any problems. “Additionally, 180-minute Etops testing completed in April required another 3,000 simulated flight cycles on the test stand before a complete inspection was conducted by CFM,” added Boeing.