Boeing dismisses doubt over 787 approval target
If Boeing manages to get the 787 certified in eight to nine months as planned, it will doubtless enjoy proving the long line of skeptics wrong. After all, to certify the airplane by the first quarter of next year will require far better execution than the company managed during the early stages of the project, when Boeing’s metamorphosis from airframe manufacturer to product “integrator” faced its first real test.
Of course, Boeing can rightly argue that the actual flight testing accounts for only a small part of the certification program, and that the extra two years it has spent straightening out production processes and helping its suppliers work through their own integration problems could work to its advantage over these next eight to nine months. In fact, early last month the company had submitted some two thirds of the type- and production-certificate “deliverables” for the 787 to the U.S. Federal Aviation Administration (FAA), according to program vice president and chief project engineer Mike Delaney. The flying program generates only about 10 percent of all the documentation that must go to the authorities before they deem the airplane ready for revenue service.
“We have a number of projects going on, so we’ve tried to work with the FAA as best as we can and they came to lay out a schedule, and that way they can plan their resources and we can plan our resources,” Delaney told reporters at Boeing’s Bomarc facility in Everett, Washington, in late April. “The FAA has told us that, as a template, about 30 days is their standard flow to approve something. Sometimes they do it faster, sometimes slower, depending on whether they have questions or comments…[it depends on] if it’s a simple submittal or a very complex submittal, but by and large they’re pretty good…They quite honestly do a great job of supporting us if we put together a good plan for them.”
Delaney said Boeing had negotiated with the FAA 3,900 separate items it must present, 60 percent of which it had submitted for compliance. Of those, “a fairly significant number” already had gained FAA approval, he added. Delaney also said Boeing has negotiated two rule exemptions and might need a third to waive an FAA amendment related to emergency lighting around exterior egress. All told, the program has also generated 152 so-called issue papers and 16 special conditions, including one that has drawn special scrutiny from the National Air Traffic Controllers Association (NATCA).
Ready for Lightning Strikes
The union, which represents some of the FAA engineers assigned to the 787 program, argues that an FAA policy issued in a December 11 memorandum titled “Policy on Issuance of Special Conditions and Exemptions Related to Lightning Protection of Fuel Tank Structure” unduly relaxes standards known as SFAR 88 set in response to the 1996 crash of TWA Flight 800. The FAA’s policy memo concedes that it can’t expect manufacturers to meet the requirements that call for “three highly reliable and redundant protective features to prevent ignition sources” in certain design areas of the fuel tank structure.
Delaney noted that he served as Boeing’s program manager for SFAR 88 incorporation “eight or nine years ago” and “actually built the first [fuel tank] inerting systems that went on the Boeing airplane.” He, therefore, has expressed a keen personal interest in the subject.
“We have worked our way through with the FAA in very great detail, every detail in that airplane, down to every fastener, every bracket, every system, every spacing, every material, and we’ve probably had more testing on that piece than on any other part of the airplane,” he stressed. “I am confident that we have done everything we can to understand, engineer and comply with that rule. Now, there were some things in that rule that both the FAA and we had to work around because it was an area where, quite honestly, the FAA got prescriptive in terms of design as opposed to writing requirements, and we had to work our way through that…
“My personal wish is these test airplanes get struck [by lightning] a lot, because... to go through this at an engineering discussion is literally at the PhD level, and you never win those arguments. But I’ve been through it, and I’m confident, and I know the people at the FAA have worked really hard and they have not compromised a bit.”
Rethinking Flight-test Plans
Meanwhile, the members of Boeing’s flight test organization will have to exhibit equally uncompromising attention to time management to successfully execute the company’s plans for maintaining its around-the-clock work schedule. According to BCA director of flight operations Frank Rasor, Boeing has moved more ground testing to the second shift, so although it typically will fly the airplanes only during the day, the 787 test program will see no down time if all goes according to plan. “It will be a 24-hour operation,” said Rasor.
Schedules call for the four flight test examples powered by Rolls-Royce Trent 1000 engines to fly 2,430 hours and spend 3,100 hours in ground testing. Two General Electric GEnx-powered test articles– Z005 and Z006–will contribute another 670 hours in the air and 600 on the ground, according to the certification plan. Boeing also plans to perform what Rasor called follow-on testing of the first two production examples for structural and electrical changes.
Under Boeing’s previous approach to flight testing, the company would assign a dedicated team to manage each airplane individually, explained Rasor. For this program, he said, the company has adopted a more holistic approach. “One of the changes is to go to a fleet-management process,” said Rasor. “So if one airplane is down and we [need] critical or important data, we would put that test on another airplane if it has the right instrumentation system and the right configuration to do that.”
One time-saving aspect of this particular test program, said Rasor, will involve the use of artificial ice shapes–glued and taped to the wings, for example–to test the airplane’s reaction to ice accretion.
“That’s a test method that has developed fairly dramatically over the years,” he said. “Before we typically had to go look for icing conditions… [now] we can do it in warm weather, basically at any point in time with those simulated ice shapes and understand the handling characteristics.”
Rasor also cited as a major time saver the use of a pressure belt system to perform the airplane’s flight load survey. The pressure belt, which consists of multiple smart sensor modules mounted on thin polymeric tape, measures pressure at various points on the skin of the aircraft to determine structural loads during flight conditions.
The old method involved an array of plastic tubes that transferred pressure from a given point on an aircraft’s skin to an electronic measuring instrument inside the airplane. It required drilling access holes on the airplane structure to route the bundles of tubes and cables, then engineers would have to ensure that none of the holes compromised the structural integrity of the airplane. “Historically, we ran all the tubing, had to plumb the airplane; it took about 30 days,” said Rasor. “Now we simply take [prefabricated pressure belts] on the wing and we’re ready to go. It’s about a seven-day process.”
Rasor explained that the first two months of the flight test program consist of type inspection authorization when Boeing personnel will work to expand the flight envelope and ready the airplane for full-blown certification testing. During that time the OEM will use the first prototype to perform flutter and all systems tests, followed by Phase 1 stability and control testing, when test pilots perform stall maneuvers and validate a firm flight configuration.
The second prototype, said Rasor, “is a lot about stability and controls, a lot about the autopilot; so airplane number two will do a lot of runway work.” Airplane Z002 will also serve as the primary platform for testing the fuel system, and most notably the fuel inerting system. The third prototype will contain a full interior, and pull duty testing for interior noise, cabin comfort and items such as smoke penetration. The fourth airplane, a fully instrumented example, will perform much of the high-speed engine performance and flight load survey testing.
“[Airplane] four for us is a significant airplane,” said Rasor, largely because it confirms fuel economy estimates. “We have to do that test with what we call pristine engines; they need to be engines that have not been abused in the test program. So we basically go do that first on that airplane; that’s going to set our standard for both the engine and the airframe.”
The fifth and sixth airplanes, the two General Electric-powered examples, together will need to fly only 670 hours and spend 600 hours in ground testing because Boeing plans to use them mainly for GE-specific trials. The sixth and final airplane will contain “minimal” instrumentation, said Rasor, and perform additional EME, or lightning testing.