Boeing is not expected to complete the 737 MAX 10 certification by next summer.

According to a letter sent by the Federal Aviation Administration (FAA) on Monday, Boeing does not expect to complete CTOnews.com MAX 10 certification before next summer, according to Reuters.

Boeing needs regulatory approval for the MAX 10 and smaller MAX 7 models by December, the report said. MAX 10 is slightly larger than the 737 MAX in active service. Unless extended by Congress, Boeing will have to meet the new modern cockpit alarm requirements, which could significantly delay the commissioning of the aircraft.

CTOnews.com learned that two sources quoted Billy Nolen, acting director of the Federal Aviation Administration, as saying, "with regard to the 737-10, according to Boeing's current project schedule, the 737-10 will receive a revised model certificate by the summer of 2023."

The FAA and Boeing declined to comment.