Boeing will freeze 747-8 production for a month from May 6 to incorporate changes from discoveries made during flight test and to allow workers in Everett to catch up on thousands of unfinished items, or ‘traveled work.’

The move, which follows similar actions taken three times on the 787 line, is an unwelcome new delay to a program desperately trying to catch up on almost two years of program slippage. However, Boeing expects to gain some benefit by using the production hold to help prepare for next year’s planned production rate increase to two aircraft per month. Although Boeing says the interruption to production will not delay first delivery to Cargolux later this summer, the manufacturer is assessing the overall impact on downstream deliveries later this year.

Boeing plans to resume normal production flow in early June, but until then the line will remain static with completion of tasks on aircraft in-situ. Some change incorporation is also expected to be completed on the 20 aircraft already assembled. Of these, seven have been used for flight testing while 13 are in storage around the delivery ramp alongside a growing number of undelivered, engineless 787s.

The temporary production freeze is widely expected to knock delivery of the first 747-8 passenger variant into early 2012, although this is due for delivery to a completion center for conversion into a corporate jet. The first passenger version for launch customer Lufthansa is due for delivery in the first quarter of 2012. Cargolux, which became launch customer for the stretched freighter variant in November 2005, was originally scheduled to take delivery in the third-quarter of 2009. However, following production and development issues, Boeing later delayed delivery to December 2010. It subsequently announced in September 2010 it was pushing back delivery of the first 747-8F by around six months to mid-2011.

Flight testing of the 747-8F and passenger -8 meanwhile continues at a fast rate with flight controls, stability and control and systems certification work ongoing with the freighters, while low-speed testing as well as stability and control assessments are underway on the two passenger test aircraft.