Boeing is putting through its Renton, Wash., factory the first 737NG airframe that will lift its current average production rate to 35 airplanes a month from the current 31.5.

Production of line number 3,878 in the NG series, a 737-800 for Norwegian Air Shuttle, is beginning with the loading of chords and webs built by Boeing’s Fabrication Division into a new automated spar assembly tool. The spar is the wing’s main support structure. Norwegian Air is to take delivery in January.

The 737 rate increase is one in a series rippling through all of Boeing’s product lines. Rates for the 737 are to increase to 38 a month in the second quarter 2013 and then reach 42 per month in the first half of 2014.

Every time Boeing steps up the rate it sets a new company production record.