For more than a decade, Boeing has been involved with developing its newest airplane, the 787. While most in the commercial airplane business have followed the press releases and available news about the airplane, remarkably little has been publicly chronicled about the details of the design, engineering and certification processes. In part, this has resulted from an aggressive stance taken by Boeing in suppressing informational leaks. Indeed, from the onset of the program, Boeing is reported to have fired employees who raised concerns internally, and brought suit against some who have spoken publicly. As with many other large corporations, it appears that efforts by Boeing to lobby the Congress, pressure the FAA, and influence the public with slick public relations efforts have become staples of the modern business model. One must wonder if firemen in Boston had not taken and distributed photographs of the fire-damaged 787 some months ago, just how much would have become publicly known about the lithium-ion battery issue.
To industry professionals, the most fundamental issue is whether the 787 is just another new airplane, and its problems representative of those one expects with the introduction of any new airplane model. The history of commercial airplane manufacturing instructs that only modest steps be taken in incorporating new technologies, and then only after use successfully in non-critical applications to obtain data on performance in service. Projected benefits to airplane performance do not justify compromises to sound engineering and manufacturing processes. In addition, commercial airplanes must be designed and manufactured such that ongoing airworthiness through maintenance and inspection can be effectively and economically achieved. That a novel design might use less fuel or carry more payload is of little consequence to airline management when the airplanes are grounded, fail to meet dependable dispatch requirements, or are difficult and expensive to maintain.
In the case of the 787, one can argue that Boeing has chosen to use too many new and unproven technologies in a single design. Many engineers have opined that the absence of effective non-destructive testing methodologies will render inspections to validate continuing structural airworthiness problematic. Further, many believe that previous experiences with composite materials in non-critical applications have reflected problems that should caution about its use in primary airplane structure. Issues related to the accuracy of computer design algorithms related to composite material buildups, crashworthiness, flammability, susceptibility to damage from lightning, and differential coefficients of thermal expansion with adjoining materials, have all been raised as potential areas of concern.
The 787 also incorporates a broad range of systems design details that are both new and, except for testing within the 787 development process, unproven. At the heart of the new systems design is an unprecedented reliance upon the airplane electrical system, which is not only used for traditional electrical functions, but also relied upon as an integral part of other “blended” systems, such as where electrical power is used in a fly-by-wire methodology to command and control hydraulic actuators in the flight control, brake and landing gear systems. Additionally and uniquely, cabin pressurization, environmental, ice-protection and liquid avionics cooling systems are also electrically powered.
Inherent with a broad reliance upon electricity is an incredibly complicated system. Starting with two enormous 250 kVA generators on each engine, the system utilizes some three times the power and twice the voltage of previous electrical systems, and relies upon a complex network of automatic sensing, switching, current return and protective devices that some experienced engineers believe will make the airplane less reliable and maintainable under the high-use profiles of long-haul airline service.
Recent public news has revolved around whether the potential for fires has been solved by the highly-touted “battery fix”. Most systems engineers appear to believe that it probably will prevent overheating and thermal runaway situations from setting an airplane on fire, but the better question may be whether the electrical system writ large incorporates too many new technologies, and is further too complicated and automated to ensure reliable performance, maintainability and safety. With an airplane substantially powered by or reliant upon electricity, and using the batteries as the final backup to the basket into which most of the eggs have been placed, that the battery technology has a history of self-ignition may call for more than isolating it from the airplane. Dependable power from the final system backup sources – in the case of extended over-water operations, for several hours – must still be a significant design target not amenable to definition by only minimum standards.
Although the industry reached a level of standardized design practice where the primary and secondary powering of systems is customarily shared between a mix of manual, pneumatic, hydraulic and electrical sources, with an incredibly high level of redundancy and reliability, Boeing has elected to discard the proven in favor of a new approach with its 787, and place substantial reliance upon a single system for powering a transport category airplane.
Experienced engineers often recommend that new designs be a decade or so behind the so-called “leading edge” of technology, thus ensuring that commercial aircraft use technologies proven in service, rather than only in theory. The military can choose to design at the leading edge of technology, including experimentation with new designs, materials and manufacturing practices, because it can place performance ahead of safety, and rely upon parachutes for an ultimate backup. Redundancy and reliability in commercial airplanes is more than a function of mere laboratory tests and mathematical projections about potential failure rates, and should not be overshadowed by promises of possible improvements to airplane performance parameters. With human payloads and high-use profiles, experience teaches that commercial airplanes are most successful when simple, sound and proven, even at the expense of reduced payloads, range or fuel use specifics.
Executives have cited responsibility to shareholders as having required the furlough or firing of tens of thousands of workers, and a principal reason for electing to have the 787 sub-assemblies and components outsourced for manufacture worldwide, with only final assembly in company facilities. But airplanes are complex machines, and cautions reportedly given to Boeing early in the program about quality-control over dispersed design and manufacturing functions appear to have become well-documented lessons in reality for a generation of executives more focused initially on share performance than product integrity.
Unknown to most outside the airplane manufacturing industry is that much of the testing and validation for certification is delegated to manufacturers. Somewhat different with the 787 was that the FAA was itself short on personnel able to meaningfully evaluate the new materials and technologies. Coupled with the fact that the minimum regulatory standards did not anticipate those new materials and technologies, oversight of the certification process became even more concentrated with the 787. Incredibly, this evolved to a point where the manufacturer was delegated substantial authority to validate its own product as an agent for the government agency of certification, and yet claim the details of how it did that work are protected from public scrutiny as trade secrets.
To experienced engineers, the 787 is not seen as just another new airplane. The totality of new designs, technologies, materials and manufacturing processes concentrated in a single airplane, its reliance upon the proper functioning of complicated systems, and the ways in which its design and manufacture appears to ignore experience with other aircraft, all serve to caution that its operation in airline service may indeed continue to be a bumpy flight.
Mark H. Goodrich – Copyright © 2013
Is the Boeing 787 Just Another New Airplane? was first published in the June 2013 Issue (Vol 10 No 2) of Position Report magazine.