The oft-critiqued Boeing 747-8 Intercontinental (747-8I) program appears finally to have found its stride following a series of development delays and struggles with performance shortcomings. Needing to adjust to soft demand in the very-large widebody market, however, Boeing (Chalets A324 and B321) recently cut 747-8 production rates from two to 1.75 per month and its 20-year projection for the large widebody market segment by 4 percent, leading to inevitable questions about the long-term viability of the latest iteration of the Queen of the Skies.
Nevertheless, during a recent Pre-Paris Air Show media gathering at Boeing’s facilities in Everett, Washington, Boeing Commercial Airplanes 747 program v-p and general manager Eric Lindblad insisted that proper demand management and further performance improvements will ensure the model will remain in production for decades.
“We [cut the production rate] because we really feel that we can maintain the skyline at 1.75 for a significant period of time,” said Lindblad. “We have to make sure that the airplane meets what the requirements are from the customer standpoint, so we will continue to identify things that improve the overall aircraft performance at the same time we have to be able to deliver this airplane at a price that our customers want to pay for it, which means we have to be able to build it at a cost that we can stand.”
Formerly Boeing’s vice president of 737 manufacturing operations, Lindblad talked of fully applying to the 747 the same so-called lean processes that have driven the narrowbody’s production efficiency–which is easier now certain “distractions” have passed. For example, in mid-May the team finished incorporating changes on the last airplane to have rolled off the line unfinished and by the end of the month it completed refurbishment on the last of six flight-test airplanes at Boeing’s Global Services & Support facility in San Antonio, Texas. This means personnel diverted from the assembly line can now return to their duties on what Lindblad called basic build.
Meanwhile, Boeing has begun testing improvements to the flight management computer and GEnx-2B engines. Meant to provide more memory and faster processing, FMC block point 3.0 promises ATC efficiency features such as Quiet Climb, Optimal Wind Trade Step and Required Navigation Performance (RNP). In February customers received an Integrated Display System (IDS) update, which improved the display and messages for ECS, flight controls and hydraulics, and enabled the airport moving-map.
While Boeing and Honeywell ironed out early kinks in the FMC that rendered it no more capable than the computer it replaced in the 747-400, GE devised and inserted the GEnx-2B’s performance improvement package (PIP) which, according to Boeing, will improve fuel burn by 1.8 percent. GE describes the package as a combination of the best features from the two PIPs designed for the Boeing 787’s GEnx-1B. The -2B PIP includes a new low-pressure turbine design and improvements to the compressor, combustor and high-pressure turbine. If all goes as planned, certification of the performance improvement package is expected by the end of this year and will result in a 3.5 percent total fuel burn improvement since the first 747-8F entered service in 2011.
Although that figure still doesn’t quite meet catalogue specifications, the airplane will gain another 340 nm of range with the reactivation of the 747-8I’s horizontal stabilizer fuel tank system, disabled before first delivery to Lufthansa because of its tendency to cause a flutter condition under certain structural failure scenarios. Once certified, hopefully by year-end, the feature will restore the 8,000 nm of range Boeing originally quoted for the 747-8I.
Even though current -8I customers don’t generally need all the extra range the tail tanks would deliver, the absence of fuel in the tail of the airplane does actually produce some fuel-burn penalty because the condition changes the airplane’s center of gravity, and thereby the trim. Once it certifies the tanks, it will, in fact, regain the resulting lost fuel efficiency.
Now building airplanes 5,600 pounds lighter than those originally delivered, Boeing has identified ways to drop another 1,600 pounds; in all, the savings contribute some 2 percent to operating efficiency, estimates Boeing. Lindblad said he would like the total to reach 10,000 pounds, and perhaps increase the -8I’s range to 8,200 nm, by around 2016.
“We have not decided to do [the range increase] yet,” he noted. “Part of that would include weight reductions, but also aerodynamic improvements on the airplane further than what we have already talked about.”
Aerodynamic improvements since first delivery of the cargo variant in late 2011 included a rudder rig and aileron rig, allowing engineers to “bias” the airplane and extract “a few tenths of a percent” operating cost improvement.
“The other thing that we continue to look at [is] how we can take advantage of additional margin on the airplane to see if there’s a way to improve overall payload capability beyond what we’ve already done,” said Lindblad. Boeing has so far managed to increase max takeoff weight by about 12,000 pounds since entry into service.
Recent program milestones included the 50th delivery of the type on May 29, to 747-8I launch customer Lufthansa. Now in possession of seven Intercontinentals, Lufthansa operated the model’s first revenue flight on June 1, 2012. Along with the seven passenger 747-8s it has sent to Lufthansa, Boeing has delivered eight VIP-configured Intercontinentals, while the delivery count for the freighter version now stands at 35.