By: Mark H Goodrich – Copyright 2016
To many experienced design engineers, the B737MAX reflects a return by Boeing to sanity after more than a decade of chasing the elusive – if not impossible – goal of combining safety, reliability, maintainability, performance and multiple new technologies within a single airplane development program.
The history of commercial airplane development instructs that modest steps be taken in incorporating new technologies, and then only after their use successfully for a decade or more in non-critical applications to obtain data on performance in service. Potential benefits to performance always sound good to the marketing department, where the search to defy laws of physics and turn lead into gold is a perennial quest, but do not justify compromises to sound design engineering and manufacturing processes. That a novel design might use less fuel or fly farther is of no benefit when the airplanes are grounded due to airworthiness directives or service bulletins, fail to meet dependable dispatch requirements, or are simply difficult and expensive to maintain.
The established methodology by which new airplanes had been designed, manufactured, evaluated and purchased since the 1930s was suddenly upset in the 1980s. Economic deregulation of the airlines, a seemingly unlimited expansion of the corporatocracy into the finance and lease business, and decisions by airlines to focus on share price over other considerations combined to create – as the young executives are fond of saying – a “new paradigm”. In executive suites increasingly occupied by balance sheet manipulators with no airline experience, greed to acquire market share trumped logic, reality, fundamentals of business finance, and the advice of subordinates and consultants experienced in airline operations. With their eyes focused on little more than executive pay and bonuses based on share price, and the creation of a marketplace to sell tickets at any cost, this race to the bottom quickly drained airline coffers. Airlines without the capital or credit to purchase were being driven to lease airplanes, and thus to lease types that were available through lessors willing to extend credit, rather than types that were efficient and suited to their route structure, stage lengths and loads. Invisible to the taxpayers ultimately footing the bill was the gifting of enormous tax advantages to banks, insurance companies and lessors willing to keep the airline business alive by leasing airplanes to airlines without the balance sheets to support borrowing of any type – a near perfect reflection of modern socialism at work through corporate welfare. Like modern young consumers, many airlines were charging to a line of revolving credit in the form of leases, while simultaneously engaged in an industry-wide suicide pact through pricing wars that would render them unable to re-establish a sound financial footing through operations. Airline shares were traded on speculative greed refracted through prisms of myth and tribal lore. Government from the administrative to the legislative and judicial, knowing the reality of the precarious condition upon which the entire industry was based, and yet absent the political courage to be honest with voters, was careful to sidestep any regulatory action that might topple the house of cards, while providing false assurances to the public that capitalism was being served and all was well.
Few people at leasing companies had experience in the airline business, and the tax advantages to lessors guaranteed profits regardless of whether purchasing decisions were good or bad. Incentives to purchase wisely evaporated, and the marketing of new airplane types became ever more a function of slick advertising. New technologies were touted and non-critically accepted as improvements. Vague representations about fuel efficiency, range and payload went unchallenged. That a modest enhancement to fuel efficiency over an operating life might fail to offset even the cost of incorporating the new technology was often unrecognized. Manufacturers quickly broke the code on the new techniques for selling airplanes, as reflected by an increasing involvement of their marketing departments to set performance specifics before engineering had even been tasked to test and evaluate how far, fast and high the new airplane might fly. Guarantees of performance were not based on actual information, but rather on projections and estimates, with knowledge that lessors would be unlikely to back away from a purchase when actual performance fell short of that represented – misrepresentations became just another stage of negotiation. Often absent were reasonably-based projections about reliability and maintainability, because leasing companies know little and care less about operations. Although they are owners and operators of airplanes, most lessors see themselves as nothing more than bankers with no duties or responsibilities beyond that of a “holder in due course” under banking and financing laws.
Into that environment, Boeing started the development of a new airplane, known at that point as the 7E7, promising heretofore unseen efficiencies. Many inside and outside Boeing pushed for enhancements to the B757, recommending a refinement scheme similar to that used to upgrade the B737 from the Classic Series to the NG Series. The B757 was a proven design needing only more efficient engines, some systems upgrades and the B777 avionics suite to enjoy another two decades or more of service with airlines worldwide. The tooling for B757 production was already amortized, costs of production would be far lower than for any new airplane, and airlines were already set up to train, operate, and maintain the airplane. All of that notwithstanding, decisions in the carpeted hallways at Seattle were clearly being made on factors unrelated to the best interests of customers, or even to the long-term interests of the manufacturer itself. Boeing elected to proceed with the new airplane development program, despite that it would include unparalleled forays into uncharted territories. In the age of outsourcing, many observers opined that senior management was playing chess with state governments, unions and its own work force, by proving to Wall Street that it could develop a new product even as it purged thousands of aging unionized workers from its payroll, and outsourced design and sub-assembly production, with minimal quality-control oversight, to low-bidders worldwide.
Based on its size and projected payloads, many saw the new 7E7 as a replacement for the B757 in any event. Open questions included how it would perform over time in service, and whether promised improvements to efficiency would be realized in bottom-line economics when measured against the much higher costs of acquisition and “teething problems” that are common to new airplane types. Boeing reacted negatively to the characterization of the 7E7 as a follow-on airplane, and in what turned out to be an understatement of significant proportion, instead stressed that the airplane would be a departure from tradition in design, materials, and manufacturing technologies. Many experienced engineers argued that Boeing chose to use too many new and unproven technologies in a single design, and many believe the jury is still out on the design and manufacturing choices employed.
To critics, the myriad gambles involved were unnecessary, and undertaken for reasons of corporate gamesmanship, rather than prudent design and manufacturing. Even ardent supporters of pushing the technology envelope were concerned that the program would be unlikely to produce real profits, a forecast validated by the troubled path from drawing board to operations. Indeed, it is increasingly likely that the 787 will never produce a profit, except as described using the tortured logic of tax accountants hired to shuffle costs into future reporting periods, and jury-rig the books in ways that make bad decisions appear reasonable.
It is within the framework of this recent history that the B737MAX has been introduced, the winner within Boeing of a decision to “fine tune” a proven product, rather than go forward with a B787 type of cutting-edge technological approach – known internally as the “Y1 Project” – to replace the B737NG. Initially the product of a time when airplane structure and systems were purposefully over-designed, the B737 has rewarded Boeing by becoming its best all-time seller, with 8,845 units delivered to-date, and pending orders for over 4,400 additional airplanes to be delivered over the next decade, some 3,072 of which are currently represented as firm orders for versions of the B737MAX.
Overlooked by many is that the B737 has undergone a continuing program of advancement by modification since its introduction in 1967. In point of fact, the first change to the size of the airframe took place before certification. Originally, the B737 was to be a 60-passenger airplane for short-haul flights, but launch-customer Lufthansa wanted 100 seats, and United wanted 110, leading to the already larger -200 Model after an initial production run of only thirty -100 Model airplanes. Since, a series of modifications has included changes to substantially all parts of the airplane, albeit mostly under the skin, and thus not apparent to the casual observer. Significantly, a measured and steady methodology for most effective and cost efficient improvement has been followed, allowing airlines using the B737 to maintain consistency in maintenance, training and operations, while simultaneously allowing Boeing to modify the existing type certificate, rather than expending enormous amounts of time and money required for wholesale certification of a new type. All of this has served to keep the B737 Series competitive, especially when maintainability, reliability and training have been factored into the long-term cost-of-operation calculus. Continuing that approach will maintain compatibility of the B737MAX with prior generations of the B737 Series, and be a significant advantage for current operators of the type.
Some argue that the incorporation of chemical milling and other production techniques to the B737 product line over time have cheapened product quality, or failed to produce a value-over-cost benefit, but overall the airplane design parameters have remained relatively stable for half a century, despite that it has grown in size and payload from the 60-passenger airplane originally designed to one capable of carrying up to 220 passengers in the largest version of both the NG and MAX Series. The jokes and jabs suffered by what was initially dubbed the SLUG – for “short little ugly guy” – have all subsided. No longer heard on tower frequencies are the routine commentaries of 1968 by other airline crews as B737s lifted off and assumed their apparently steep initial climb profile – “nice punt United”.
And so, the B737MAX is starting its flight test program on the way to becoming the “fourth generation” of the B737 Series. The rosy forecasts of marketing and estimates by computers will now be subjected to the acid tests of performance under actual forces of lift, drag, and gravity in real world conditions.
Initial marketing efforts – sufficient to garner more than 3,000 orders before the B737MAX first flew in January of 2016 – highlighted the more significant changes to airframe, engines and systems, and in most cases were presented in terms of how fuel efficiency would be improved, noise would be lowered, or carbon, nitrogen oxide and carbon dioxide emissions would be reduced. Not surprisingly, the early projections of performance details have resulted in some variations as to those predictions. Whether the airplane will ultimately achieve more or less than a 14% improvement in fuel efficiency, a 40% lowering of its noise footprint, or a 50% reduction in emissions, it is safe to say that each and all will be improved to some extent. And, the reasons behind those improvements will be a net result of multiple changes to the design and technologies employed.
Principal among the changes are the CFM LEAP-1B engines, which produce modestly more thrust than the CFM-56 model engines on the B737NG Series, and the Classic Series before that, but are expected to realize a panoply of efficiency improvements arising from both design and the incorporation of state-of-the-art materials. Engines can very effectively utilize carbon fiber, ceramic and matrix composite materials, and the LEAP-1B makes good use of that capability from the fan and fan case through to the high pressure turbine. It is expected to perform at a reduced weight without sacrificing material strength at high operating temperatures. Wing integration – the way in which the engine-to-wing interface has been designed to improve aerodynamics – will also contribute significantly to a reduced drag profile. In combination with increased fuel capacity, the improved engine efficiency will contribute to a projected increase in range of some 20% over the NG Series.
To those familiar with prior models of the B737, the tail will sport a different look, as the need for flow vortex generators has been eliminated with a redesign of the aft fuselage, APU inlet, tail cone, APU exhaust, and tail cross section. Once again, a significant reduction in drag is projected to result from this redesign.
I have been generally critical of winglet technology over the years, not because of flaws in the theory, but rather the ways in which operational realities have been overlooked in the design process. The promises of marketing regarding winglet efficiencies have seldom been realized in service due to enormous increases in parasite drag that often offset some or all of the reductions in induced drag. Indeed, changes to operating profiles that are impractical to the realities of airline and air traffic control operations have often been required to achieve any real efficiencies from winglets on all but the longest sectors at altitude. At last, Boeing appears to have broken the code on this issue, moving away from the “bigger is better” approach in favor of a smaller up-and-down configuration that enables laminar flow while reducing induced drag, and without introducing unnecessary structural and aeroelastic loads to the wings. Boeing believes this change alone will account for a one to two percent efficiency improvement, and I think that is likely to be achieved.
In conformance with the basic tenant of airplane design that systems should be modified incrementally, Boeing has put one toe in the water of “fly-by-wire”, using the technology for only the spoilers on the B737MAX, while retaining the fundamental control system design as on prior models of the B737 Series. This should have the effect of improving performance and reliability, while reducing maintenance, inspection requirements, and system weight.
Modernizing the avionics suite and flight instrumentation is an extremely important part of making the B737MAX easily upgradeable over the next two decades, and includes much more than the very apparent change to the Electronic Flight Instrumentation System. The screens will be larger as on the B777, but more importantly will include many presentation improvements common to other Boeing models, and modern flight decks generally. The incorporation of an onboard network system will not only allow for the immediate use of enhanced system control modules, built in test event (BITE) systems for faster trouble isolation by maintenance, and advanced data collection capabilities, but also provide the platform for subsequent upgrade as more airplane-to-ground connectivity becomes a requirement for air traffic control and other purposes. And, in the nature of a benefit not generally appreciated, transition and upgrade training should be easier as between Boeing models, due to enhanced commonality of the instrumentation and flight deck presentations. Instructors and check airmen have been asking Boeing for years, “Why can’t Renton and Everett at least use the same terminology for switches, functions and displays on different models of Boeing airplanes?” Maybe the B737MAX will respond to their pleas.
It has been said that a flight test is better than one-thousand expert opinions, and flight testing for the B737MAX is now underway. Boeing has announced that approximately eight airplanes will be built and used for the test program, with certification and delivery of the first models to launch customer Southwest Airlines scheduled for mid-2017. It is axiomatic that a lot can happen during testing and certification, but I am impressed with the more traditional approach Boeing has taken in developing the B737MAX, and optimistic about the success of the program as to Boeing and its customers.
Critics argue that it was only the pressure of competition from the Airbus 320neo that compelled Boeing to shelve the B787-like “Y1 Project” in favor of enhancement to the existing B737NG Series. Others say that harsh lessons from the B787 Program have been learned by the new generation of leadership at Boeing, and caused a return to the methodologies instructed by its successful leadership in the design and manufacture of commercial jet airplanes over the past sixty years. Whatever the true facts on that issue, to experienced engineers, the B737MAX appears to reflect a return to sanity at Boeing.
Mark H. Goodrich – Copyright © 2015
“The B737MAX: A Return to Sanity” was first published in the March 2016 Issue (Vol 13 No 1) of Position Report magazine.