When the first Boeing 787-9 Dreamliner lifted off on its inaugural flight from Paine Field in Everett, Washington, USA, last September, it began a nine-month period of flight testing that went as smoothly and successfully as any in the company’s history. That success didn’t happen by chance. It came as the result of years of planning and design work. Furthermore, that success didn’t just mean the airplane was certified; it also demonstrated that the Dreamliner had transitioned from a technological leap to a stable platform.
Before Boeing gives the green light for a first flight and the start of flight test activities, the team undertakes an arduous process of ensuring the airplane is flightworthy, with years of design iterations, laboratory tests, extensive analysis, and detailed planning across numerous organizations.
These steps leading up to a first flight are common across all of Boeing’s major programs. Development of a new airplane, whether it is an all-new platform or a derivative, is guided by a series of gates, each associated with specific criteria to ensure that design objectives and safety and regulatory requirements are satisfied. The decision to offer a new airplane comes from a detailed understanding of the market’s needs, which is among the earliest of gates in the development process. Design refinements, reviews and the finalization of the design comprise the next steps. Finally, production and test readiness and delivery evaluation are completed.
As the program transitions through these phases, design and project planning details narrow in scope from concept to a focused plan. Before passing through each milestone, all outstanding issues and risks are cataloged and assigned closure plans according to program timelines and requirements. In the period between each gate review, status checks serve to ensure that plans are progressing as expected.
And while start of production and approval for flight testing are among the last gates, the work required to pass through them begins to take shape in the earliest stages of the program and evolves as the program passes its design milestones.
Flight test plan
Developing the detailed flight test plan occurs in collaboration between design and test engineers and program leadership. The plan includes a wide range of considerations, from the highest level of deciding how many airplanes will be part of the testing effort, to the detailed definition of test requirements, specific missions, instrumentation definition and installation, critical path network development to determine the order of testing, test part procurement, and spare-parts planning and procurement. Many contingency plans are developed to address geographic considerations for weather and seasons, as well as test facility availability and personnel planning.
As the airplane design becomes more focused, so do the plans of the flight test program. Fleet size, specific missions and sequencing, configuration, program footprint and test requirements can all change as program priorities evolve. Scenario planning exercises, wherein alternate test program options are devised and evaluated, are often used to determine the best course of action. Proposals to utilize new testing methods or alternatives are welcomed and often pursued.
One example of a change made to the 787-9 testing plan was the decision to use 787-8 test airplanes in the flight test inventory to conduct a portion of 787-9 testing not explicitly requiring that airframe. This meant more testing could occur early and simultaneously, enabling the team to be more efficient. Additionally, after initial consideration of conducting extreme weather conditioning at international locations, the McKinley Climatic Laboratory at Eglin Air Force Base was used for the simulation of extremely hot and humid conditions. This enabled the team to address the seasonal limitations that could have extended the time it took to complete tests. The team focuses on designing a test program that satisfies all requirements as efficiently and safely as possible, and much effort is applied during these early planning phases and gate reviews to ensure that this occurs.
The specific layout of a flight test program varies according to the airplane design. Flight testing of a new component or software version on an established platform, such as an upgrade to an in-flight entertainment system, occurs regularly, and typically does not require extensive planning and reviews. At the other end of the spectrum is the testing required to certify an entirely new airplane. The 787-9, as a derivative, came in further down the spectrum, but not at the extreme end. The most visible change with the 787-9 is a 6m (20ft) increase in length, which provides additional cabin layout flexibility and cargo capacity. The change in length drove other accommodations such as adjustments to the main landing gear, and structural and systems changes. The flight test program thus focused on these elements of differentiation from the 787-8. Other design enhancements also required testing, such as hybrid laminar flow control, an industry first that reduces drag around the horizontal and vertical tail, thereby saving fuel and reducing emissions.
All facets of test program development and execution are the responsibility of Boeing Test & Evaluation (BT&E), in conjunction with the airplane program. An organization within Boeing’s Engineering, Operations & Technology branch, BT&E is engaged in airplane and laboratory test programs before and following every major program. Experts from Flight Test Engineering, Data Systems & Technology, Flight Operations and Flight Test Manufacturing are involved early in test program coordination and provide inputs into those aspects of the design process that directly affect the test program structure.
These include: test fleet layout and individual airplane mission development; test fleet build configuration and integration into the manufacturing process; test requirement collaboration with design engineering; instrumentation definition, allocation and integration; and representation of flight test considerations in all program discussions and reviews.
Within BT&E, specific groups contribute unique elements of the testing and evaluation disciplines. The Data Systems & Technology team specializes in the design, manufacture and operation of onboard and ground-based data acquisition, analysis and display systems. Flight Test Program Management integrates BT&E groups and interfaces with program leadership. Flight Operations includes pilots and other specialized flight deck system experts. Flight Test Engineering includes operations, analysis, instrumentation installation and configuration, atmospheric sciences for meteorological analysis and photo/video services. Flight Test Manufacturing, Quality Assurance and Flight Analysts maintains and modifies the flight test airplanes, including installing instrumentation and support equipment and quality control. The Lab Test & Evaluation team provides an array of test and analysis capabilities for testing better suited to the ground or before an airplane is available, ranging from individual components to integrated, full-up system testing. Metrology provides calibration and certification for test assets. Finally, the Test Operations Center & Logistics team offers visibility of organizational readiness and assets, and provides logistics and facility support for coordinating local and remote testing.
In the case of the 787-9, BT&E worked closely with the 787-9 program, part of Boeing Commercial Airplane’s Airplane Development team. Members of BT&E were collocated with the program team, served on the leadership team and were fully integrated to ensure a common understanding of priorities and plans.
The 787-9 test program, like all major test efforts, saw many incarnations. One element that remained consistent was the decision to use three primary test airplanes with staggered first flights. These three airplanes, ZB001, ZB002 and ZB021, received extensive instrumentation packages; two other airplanes, ZB197 and ZB167, were production airplanes and thus contained minimal flight test installations. Of the five 787-9s involved in testing, three were configured with Rolls-Royce engines (ZB001, ZB002 and ZB197); and two were outfitted with GE engines (ZB021 and ZB167).
This combination of test airplane assets provided the ability to lay out the testing efficiently and minimize downtime within the fleet. If one category of testing encountered an issue or a test part was not ready, testing could be reallocated to keep the fleet in the air and the program progressing. Some test phases, such as flutter, were tied to a specific airplane: ZB001 for Rolls-Royce engines; and ZB021 for GE engines. Likewise, the team defined portions of testing that could be moved between test airplanes to respond to program priorities, program status and airplane readiness, including tests for stability and control, aero performance, autoflight and flight controls.
And while the team was able to be flexible in assigning much of the testing, each airplane was outfitted with some unique instrumentation that drove its primary missions.
ZB001, the first 787-9 to fly, was outfitted with full instrumentation racks; water barrels with load banks; a flight test tailskid; a trailing cone; a load monitoring system; a telemetry system; a display system to visualize test parameters on additional displays in the flight deck; and systems to generate modifications for test scenarios (altering control laws, introducing intentional faults, and so forth).
This airplane focused on flutter, aero performance, stability and control, flight controls, autopilot and brake tuning, as well as demonstration activities for international regulators. The second 787-9, ZB002, included elements of the production interior and the associated data systems. It also had a removable trailing cone and an oxygen analysis system. Primary test objectives for this airplane included systems validation, the environmental control system, autopilot tuning, avionics, and propulsion and fuel systems.
ZB021, the third 787-9 and the only airplane in the primary flight test fleet with GE engines, was outfitted similar to ZB001 with a focus on flutter, aero performance, stability and control, flight controls, and brake tuning and performance.
By design, the two production airplanes (ZB197 and ZB167) had very little flight test unique monitoring equipment as they were used for functionality and reliability testing, extended operations (ETOPS) validation and testing of selected systems and avionics.
Flight test results
The entire 787-9 test program proceeded largely as the first flight had – smoothly and as planned, with few surprises. The team capitalized on the stability of the airplane design, its maturity and its reliability, which meant the airplanes were available and ready to fly as scheduled. A major contributing factor was the maturity of airplane systems, which were fully qualified and tested before first flight. With more than 550 flights in more than 30 locations around the globe, the team was able to shift testing as needed to accommodate hardware and software updates, or in some cases, to take advantage of test modules completed ahead of schedule. Nimble responses to changes of scope or schedule were feasible. Successes such as these went a long way to sustaining momentum throughout the project, a particularly important achievement in any test program.
The 787-9 provided Boeing with an opportunity to demonstrate that the 787 design and technologies are well established and that the model fulfills its design objectives. Time and again, flight after flight, the airplanes delivered throughout the test program. Much of that success was clear evidence of the rigor of the development, design and build processes; and the talent and efforts of those who support them.
Perhaps most important, it proved that Boeing had succeeded in leveraging and extending 787 technology to produce the 787-9, which, as chief 787 pilot Capt. Randy Neville described after the “no squawk” first flight, “did exactly as we expected”, leading to on-time certification and delivery of the 787-9 in June 2014.
John Bradford is a test director/test operations engineer based within Boeing Test & Evaluation’s Flight Test Engineering group. Bradford was a principal contributor to the 787-9 test program development and later an Operations team lead on ZB001, the first Boeing 787-9 Dreamliner.