Boeing is considering optional outer wing sections as a way of satisfying both mid- and long-range markets with the same basic 7E7 airframe options.

The company plans to develop common 7E7 models to replace early 767s, Airbus A300/A310s and McDonnell Douglas DC-10-size aircraft on mid-range routes between 5,550km (3,000nm) and 7,400km, as well as to provide 777-like capability on ultra-long-haul routes between 13,880km and 14,800km.

Boeing 7E7 vice-president Mike Bair says airlines willingly buy aircraft with "latent capability" for fleet flexibility and higher residual values. Although the structure could be "exactly the same", Bair says the wingspan is the "biggest complication" in designing a common solution to both markets. The long-range variant, both baseline and stretch, is expected to be configured with a span of around 56m (184ft), whereas Bair says the optimum span for the mid-range version would be "more like 150 or 160ft [46 or 49m]. We immediately get into gate compatibility issues."

To solve the same conundrum with the 777, Boeing devised a folding wingtip option that was never adopted. However, the smaller size of the 7E7 means the wingspan question is likely to be more serious, and Boeing is looking at "other options to satisfy that", Bair says. Although no details have been given, Bair confirms that a form of modular wingtip section option is being considered in lieu of the folding wingtip.

Meanwhile, Boeing filed for both 7E7 type and production certification with the US and European regulatory authorities on 28 March. Bair says this "major milestone" is one that Boeing "didn't pass on other recent derivatives".

The company also plans to draw up a definitive list of requirements within a month on where to locate the 7E7 final assembly line. Several undisclosed locations are being considered. Bair says the final choice may not "necessarily be in the USA", adding that "we haven't ruled out multiple sites".

Source: Flight International