Boeing delivered 126 aircraft in the second quarter, including 100 737s, six [correction–18–see the comment below] 777s, five 747s and three 767s. This is the equivalent of 33 737s a month (33.3 to be precise), six 777s, 1.6 747s and one 767.

Boeing has quietly been increasing the production rate of the 737 and has the capacity at its Renton plant to go to 40 a month–if the supply chain can perform. Boeing has been studying whether to go this high, which would match Airbus’ planned 2009 rate. There is a reluctance on the part of some to do so because of haunting memories of the 1997 737 production fiasco (though the current rate now exceeds the rate then), and also because of the emerging economic uncertainties.

But the 737 line is dramatically oversold in 2010, and Boeing is losing sales now because the line is essentially sold out to 2014. With a two year lead time required for suppliers to gear up, it would be mid-2010 before the production could be dramatically increased.

The 777 line average rate of six per month for 2Q08 is one less than the seven a month capacity of the Everett line. Boeing is offering the 777 as interim lift to accommodate airlines hurt by the 787 delays.

The 767 line, at one a month, has lots of room to grow if the supply chain is there to support it. But suppliers are pressed, running at full capacity serving Boeing and Airbus on other models. Increasing 767 parts production is problematic. Boeing has been thinking of going to 2-2.5 767s a month to support aggrieved 787 customers, and now with the uncertain prospect of winning some of all of the KC-X USAF tanker business, Boeing has some decisions to make. A full tanker award would be another 1-1.5 767s a month.