Boeing stopped moving airplanes forward on its 747-8 production line in Everett, Wash., today to help mechanics complete work that has mounted as the company prepares to increase production of the type from 1.5 to two per month starting next April.

“In addition, as sometimes happens with the introduction of a new minor model, starting up regular production of the Intercontinental has created some challenges that are best addressed at this early state of the ramp-up,” a Boeing spokesman told AIN today. Some of those “challenges” involve what the spokesman described as a rebalance of the production line to complete some unfinished work and incorporate design changes driven by certain flight-test discoveries.

“That will allow us to have a smoother transition to a production increase in mid 2012,” he said. The Intercontinental–the passenger version of the 747-8–flew for the first time on March 21. The cargo version of the airplane flew for the first time in February 2010.

Boeing expects the halt in line movement to last until June 7. It does not expect the measure to affect the schedule for first delivery of the 747-8F Freighter to Cargolux by midyear.