Boeing has confirmed the exterior lines for its new 747-8 aircraft but is still weighing alternatives on a handful of more specific issues before the final configuration of the aircraft is decided in the third quarter, program head Jeff Peace said yesterday.

Boeing is now at the stage where it is "making tradeoffs at [the] detailed level," said Peace. These issues include cabin architecture and whether advanced alloys should be used on some individual components. Engineers have still not decided whether it is worth extending fly-by-wire technology to the outboard ailerons (DAILY, May 5).

Regarding the aircraft interior, questions such as which side the stairs should be on and the location of galleys are still under discussion. Boeing is proposing taking the galleys from the Door Four area and moving them upstairs, which would create space for 12 more seats on the main deck. The airframer also is still undecided on whether to include the self-dimming windows that are being developed for the 787.

Representatives from 10 different airlines were recently invited to examine 747-8 cabin mock-ups, and Boeing is now analyzing alternatives based on their input. Decisions on these issues will be made "in the near future," Peace said.

The freighter version of the 747-8 remains on schedule for first delivery in the third quarter of 2009, said Peace. At least one aircraft each will be delivered in 2009 to launch customers Cargolux and Nippon Cargo Airlines. Rollout and first flight are planned for late 2008. The 18 orders received so far are all for the freighter version, and Peace repeated his prediction that the first passenger version order will be signed this year. First delivery for the passenger version is expected in 2010.

Boeing has now confirmed the wing shape for the -8 and wind tunnel tests have not prompted any changes to the wing span, surface area or fundamental design, said Peace. The wind tunnel tests showed that the wing exceeds the goals Boeing originally set for wing efficiency, said Peace.

The airframer believes it won't have to conduct static test to failure on the wing. Because fundamental structural locations are unchanged from the -400, the structural analysis from the -400 will still be valid, Peace said. Boeing is still deciding whether it will modify existing wing production tools or build new ones.

An entirely new nacelle design is also being used in the -8. Although the GEnx engine used on the 787 is being employed on the 747-8, some modifications will be necessary. For example, the fan diameter was reduced slightly to improve engine ground clearance. Boeing tried raising the engine position, but this had too much effect on the aerodynamics, said Peace.

The two main areas where additional composite materials will be used are the nacelles and the new trailing edge flaps, which are now single- or double-slotted, instead of triple-slotted. The wing and body will still be metal construction, but Boeing is examining the alloy parts used on the 777 and those planned for the 787 to decide which to incorporate on the 747-8. The new alloys can be used to build more strength into a component while keeping it the same size as in the -400.

The mix of U.S.-based and overseas production will essentially remain the same on the -8, Peace said. Incumbent -400 suppliers are being given first option to design similar parts for the -8, although Boeing will compete work for new parts. "We don't expect a fundamental shift of work from Everett" to overseas companies, said Peace.