Boeing 787 (partie 1)

There will be limited testing on two additional airplanes for a total of
eight airplanes (not four for a total of 10). The additional testing is
driven by the requirement that some of the testing be done on airplanes
in production configuration as opposed to flight test configuration. One
airplane will do some ground testing. The other will do some flight
testing.

Boeing disperses 787 test fleet

By [url=mailto://]Jon Ostrower[/url]

Boeing's 787 test fleet has fanned out from its home base in Seattle,
Washington as the type pushes through certification toward its revised
mid-first quarter 2011 first delivery to All Nippon Airways.ZA001
recently completed runway takeoff and landing performance stability and
control (S&C) evaluations at Edwards Air Force Base in southern
California, as well as wet runway trials at Roswell, New Mexico.

ZA001 transitioned to southern California on 16 August and recently returned
to Roswell on 2 September ahead of planned rejected take off testing.
Testing at Edwards Air Force Base included velocity minimum unstick
(Vmu) testing that saw the aircraft's tail scrape along the runway on
takeoff roll to determine the minimum flying speed of the 787 at
different configurations.

ZA002 is currently participating in the
programme's first international remote testing in Keflavik, Iceland,
where the aircraft is taking advantage of the airport's perpendicular
runways, all equipped with instrument landing systems and historically
high winds for crosswind handling characteristics. The aircraft arrived
in Iceland on 1 September and flew its first round of S&C autoflight
evaluations on 3 September with crosswind speeds of 28kts to 32kts."We've
been watching for the right weather conditions for some time," says
Scott Fancher, 787 programme vice president and general manager. "The
team was happy to see the forecast in Iceland met our needs and we
deployed to Keflavik earlier this week."Boeing expects to certify the 787 for takeoffs and landings of up to 25kts of crosswind.

ZA003 has been undergoing hot weather trials since arriving in Yuma, Arizona
on 28 August, with testing in conditions in excess 38C (100F). Boeing
says the aircraft is expected to remain on remote testing for roughly
seven more days.

ZA004 has spent nearly its entire time in the
flight test programme based out of Southern California Logistics Airport
in Victorville, California. Since 7 July, the aircraft has been
undergoing flight loads survey, comparing loads observed on the aircraft
to those modelled during the aircraft's design while measuring
"external pressure distributions throughout the flight envelope", says
Boeing.ZA004 is now expected to transition to Glasgow, Montana,
says Boeing, for an unspecified next round of testing. Wokal Field in
Glasgow traditionally has been the airframer's preferred site to host
community noise evaluations to map the acoustic profile of its new
aircraft.

ZA005, the first of two GEnx-1B powered 787s, has
remained at Boeing Field for simulated ice shapes handling and stall
characteristics mimicking worse-case-scenario ice build up on the
leading edges of the aircraft's wings, horizontal and vertical
stabilisers.

ZA006, Boeing's sixth 787 test aircraft has yet to
fly, though was fuelled for the first time on 3 September at the
company's Everett, Washington factory in preparation for first auxiliary
power unit and engine runs prior to its first flight, which is expected
late this month.Boeing plans to add two more 787s to the flight
test campaign, Airplanes Eight and Nine, both in the ANA production
configurations. Airplane Eight will be used for ground testing, while
Airplane Nine will take part in extended twin-engine operation testing
and systems functionality and reliability evaluations.Five 787
test aircraft have completed more than 1,650h of flight testing covering
more than 540 flights.

Boeing expects it will accumulate 3,100h of
flight testing spread across its General Electric GEnx-1B and
Rolls-Royce Trent 1000-powered 787s.

http://www.flightglobal.com/articles/2010/09/03/346997/boeing-disperses-787-test-fleet.html

Meanwhile, ANA said that its operations will not be significantly affected by the initial 787 aircraft which are around 4 tons overweight.

“Our plan is to install the first 787s into short-haul routes so that the impact of being overweight will remain minimal,” Gunji noted.

On the other hand, ANA has decided that it does not intend to restart its evaluation of Very Large Airplanes (VLAs) which once included both the A380 and the 747-8 Intercontinental

Despite Boeing's strenuous efforts to reduce the 787 Dreamliner's weight, the plane weighed more than expected when it first rolled out two years ago.
And days before the new plane's maiden flight last week, Boeing published a document for airlines that suggests to some weight-watching industry analysts that the 787 still exceeds its original target weight by a few tons.
Airlines have ordered 840 of the pioneering composite-plastic planes based on Boeing's projections for its range, payload and fuel efficiency — all reduced by added weight.
In an interview, 787 chief project engineer Mike Delaney insisted the weight has been stable for the past two years.
And he said the Dreamliner will meet its targets for range and payload and still deliver on the original promise of being 20 percent more fuel efficient.
The 787 "is still meeting that commitment," Delaney said.
Weather permitting, the second 787 is scheduled to fly at 8:45 a.m. today from Paine Field in Everett, landing at Boeing Field in Seattle after its first test flight.
Excess weight is a constant worry on any new airplane program. On the composite-plastic 787, the concern was amplified this year when Boeing discovered a structural flaw in the design and had to reinforce sections of the wing/body joint with titanium fittings.
One number Boeing won't disclose is the basic weight of the empty plane — it never does during development. That fed speculation as the company made the modifications this fall.
"The 787-8 appears to have evolved from a once-elegant composite design to one saddled with carbuncles of heavy titanium added throughout for strengthening," Morgan Stanley financial analyst Heidi Wood wrote in an October research note.
Wood downgraded Boeing stock to the equivalent of a "sell," citing concern about the weight of the airplane, among other issues.
Shortly before last week's first flight, airlines received a briefing document that listed the maximum allowed takeoff weight of the jet as 9.25 tons heavier than in the version published two years ago.

Delaney said the document doesn't mean many tons of weight have been added. Rather, he said, it describes the plane's allowed operational weight, which Boeing has bumped up after its modeling and analysis showed the airplane structure to be strong enough to carry extra loads.
That means airlines can load the planes with more fuel and thereby meet payload and range requirements, despite the heaviness lingering from two years back.
Delaney conceded that, when the first large sections of the Dreamliner were built, the 787 indeed was heavier than projected.
In 2006, the target empty weight of the plane was 108 tons, according to internal Boeing documents from the time.
Because of "the initial weight issues ... in the 2005, 2006 time frame," Boeing either had to take the extra weight out or increase weight allowances to carry more fuel, Delaney said.
Since then, however, Boeing's weight-control programs have kept the basic empty weight of the plane in check, Delaney said.
Engineers have been able to counter weight growth due to design adjustments with a series of offsetting reductions.
"By and large," Delaney said, "we have been able to stay fundamentally pat for about two years."
Allowed now to carry more fuel, the jet will be able to fly fully loaded as far as advertised.
But there is an economic penalty from carrying more weight. A heavier plane burns more fuel per trip, increasing fuel costs to the airline.
Yet, Delaney insisted Boeing still will reach the Dreamliner's fuel-efficiency target: an average 20 percent improvement over today's airplanes.
He said 787 engine makers Rolls-Royce and General Electric are working on improving fuel consumption. That, along with Boeing's weight and drag reduction and other improvements, will make up for the fuel-burn penalty that comes from bumping up the weights, he said.
Nelson Klug, an engineer who worked for both Boeing and Douglas Aircraft and who now is senior director of consulting at aviation firm Avitas, said the various weights listed in the document — takeoff weight, landing weight, zero-fuel weight and others — suggest to experts the size of the weight growth in the basic empty airplane.
"It's not unreasonable to assume that the operating empty weight is about 10,000 pounds (5 tons) heavier than what was originally on the drawing board," Klug said.
Making a rough "back-of-the-envelope" calculation and feeding estimates into his computer models, he said that on a flight of 5,000 nautical miles, with all else the same, a weight increase of 10,000 pounds burns about 450 extra gallons of fuel. That would cost the airline an extra $1,000 or so.
In addition, he said, even if the engine makers and Boeing do improve the fuel burn to compensate for that, the jet also will face heftier airport landing fees, which are based on weight.
Delaney, though, remains confident Boeing can "continuously improve the airplane" and will meet the expectation that the Dreamliner's fuel and economic performance will be "a game-changer."
Boeing began to communicate the new operational weight limits in the recent planning document to airline customers starting about a year ago.
The figures include margins for added weight during development and adjustments during flight tests, and so won't need to be increased because of the recent wing-joint reinforcements, Delaney said.
"We absorbed that into our development and flight-test allowance," he said.

ZY998 is going to work.


That is Boeing’s fatigue airframe for a standard-sized 787-8, which is beginning a three-year simulation of how well the industry’s first composite aircraft will hold up to everyday takeoffs and landings. The tests will be conducted round-the-clock, seven days a week.


When Boeing officials briefed reporters on its certification test cycle in May 2008, they predicted the tests on the ZY998 airframe would begin in the first quarter 2009. That means the fatigue test program is running about 18 months behind schedule. (That’s better than deliveries, which are now about 33 months late).


Fatigue test conductor Peter Brownlow says the daily testing will measure the wear-and-tear that 787s will experience in their lifetime. They are conducted in a metal cage that surrounds the entire 182 ft.-long airplane on the northwest corner of Boeing’s widebody manufacturing headquarters in Everett, Wash.


Boeing has installed more than 100 mechanical devices to the airframe’s exterior to simulate the pounding it will face during a lifetime of service that typically lasts 20-30 years. The various test devices apply mechanical pressure through pounding, pulling and twisting to specific areas on the airframe, such as its leading edge, fuselage or vertical stabilizer.


Fatigue testing simulates an entire flight, beginning with taxi through ascent, cruise and descent back then to taxi. The tests are aimed at creating a data set for the airframe’s durability, regardless of the multiple flight profiles that Boeing’s customers will put it through, says fatigue test director Ray Clark.



Fatigue tests are different from the static testing that Boeing has underway on ZY998, the fatigue article’s sister airframe.


ZY998 was designed to simulate extreme loads that a 787 might face in once-in-a-lifetime emergencies. The most pronounced of these was to pull up on its composite wings at 1.5 times the rate they would normally be expected to flex.


In fatigue tests, Boeing studies the effects of long-term operations. They serve three purposes: they are necessary for certification; they aid Boeing’s designer team as it works on the higher gross weight 787-9 series, and they are an important reassurance in Boeing’s marketing campaign for the airplane, which introduces the industry’s first non-corroding composite airframes as a way forward because they are light, strong and resist age-limiting corrosion.


Despite their different purposes, static and fatigue tests do have one similarity. They both measure the airframe’s actual performance against the predictive analysis that Boeing’s design team used to create it.


The difference is that the static tests are measuring performance that pilots will see. Fatigue is more a measurement of issues that an airline’s overhaul and maintenance team must deal with. Boeing has been telling airlines that the 787 will last about twice as long in service as current generation aircraft before it will need serious attention from their O&M crews.


A 787 is built for a nominal 44,000 cycle lifespan -- 44,000 takeoffs and landings. The fatigue tests will be conducted for certification at twice that number and actually involve some 165,000 cycles.


Until the fatigue certification cycle is complete, airplanes that Boeing delivers will be limited to half of their demonstrated number of flights. But that is a restriction with little meaning since 22,000 cycles would be hard to achieve in just three years of operations.


Normally, long-range aircraft like the 787, which will easily be able to stay aloft for 10, 12 or more hours on 8,000 naut. mi. flights, do not accumulate nearly as many cycles as workhorses like the 737, whose normal stage length is 400-600 mi. on flights lasting 1-2 hr.


Still, launch customer All Nippon Airways plans to introduce the 787 on domestic and regional routes, such as into China, that will last only a couple of hours. So some ANA’s airplanes could build up cycle times quickly.

ZA001 experienced an engine surge. The replacement engine is already in NM and being installed. Boeing and Rolls-Royce are working together to understand the root cause but initial understanding is that this is an isolated event. There is no impact to other airplanes and no relation to the test-stand incident from earlier.