Even after eight years of development, delays and attempted recovery, Boeing still is not quite ready to share the 787's spotlight with another widebody programme.
The 787-10X is now moving forward to a launch decision, completing a family of three complementary variants, says Ray Conner, president and chief executive of Boeing Commercial Airplanes.
Boeing likes to portray the 787-10X as any airframer's ideal situation: a small risk carrying possibly a huge reward.
"That airplane is pretty straightforward," Conner says.
The 787-10X simply adds a fuselage plug that extends the payload capacity of the 787-9 airframe, sacrificing only an acceptable amount of range. It is aimed at high-density trunk routes emerging within Asia, as well as established connections between the Europe and the Middle East and North America and Europe.
Measured in seat-mile costs, Boeing claims an advantage for the 787-10X over the Airbus A330 greater even than the 20% margin once quoted for the 787-8. Boeing estimates a market size of as many as 10,000 aircraft, says Pat Shanahan, Boeing's executive vice-president for airplane programmes.
The caveat to Boeing's claims is that the 787-10X depends on whether Boeing can achieve its performance promises on the 787-9, the 787-10X's parent airframe. Airlines must wait two more years to know if the 787-9 specifications translate into operational reality.
"We're on track today we're actually starting to produce detailed parts kind of further up into the supply chain right now," Conner says. "Now it's just a matter of executing."
Rolls-Royce is aiming to put the latest variant of its Trent 1000, designated the 1000-TEN, into service in 2016 - a powerplant which it intends to offer for the entire Boeing 787 family including the proposed -10X.
The manufacturer is intending the engine to offer up to a 3% improvement in specific fuel consumption compared with the current Trent 1000 baseline. It will be certified to 76,000lb (338kN) thrust but will be able, if required, to provide 78,000lb.
The engine will typically deliver 70,000lb for the 787-8 and 74,000lb for the -9.
Rolls-Royce vice-president for strategic marketing Robert Nuttall says the -TEN will take advantage of technologies from the Trent XWB and Advance 3 programmes.
It will include a rising-line intermediate compressor and blisks from the XWB and high-pressure turbine and air system features from Advance 3. The manufacturer insists the updated engine will provide the lowest "real life" fuel-burn for each member of the 787 family.
Rolls-Royce's Package-A version of the Trent 1000 has given way to the Package-B this year, and the Package-C - offering a 1% improvement on the -B standard - will succeed it in 2014.
The 1000-TEN will provide a further 2% improvement, and become available in the first half of 2016 on the 787-8 and -9.
General Electric in June certified a 75,000lb version of its GEnx-1B turbofan for the 787, boosting maximum take-off thrust by 7% from the 70,000lb of the baseline engines on the type. The upgrade applies to three of the 14 approved GEnx-1B variants available to customers.
The three applicable engines for the thrust upgrade can be modified by replacing the existing thrust rating plug in the engine monitoring unit with the 75,000lb-thrust plug, which a new maximum thrust setting to the powerplant.
Engine availability is one of the most critical items pacing entry into service for the proposed 777X, which remains generally timed for the end of this decade. It will be four years before an engine is ready to meet Boeing's still-unspecified thrust requirements for the 777X. By comparison, Boeing launched the 737 Max last year with the CFM International Leap-1B less than three years away from certification.
Unlike the 737 Max, however, replacing the engines, adding winglets and cleaning up the aerodynamics may not be enough to make the 777X appealing to airlines. The complication of a redesigned wing could make the scale of the 777X project perhaps closer to the 747-8 than the 737 Max.