MAY 2016 | 15 design and performance limits and see how it reacts, a challenge that Boeing pilots readily accept. “You’re taking the airplane past where we let commercial pilots go,” Hanley said. “Our goal is to get an airplane that’s safe and reliable.” Since February, the first two 737 MAX airplanes have averaged around 20 test flights a month, initially traveling from Seattle to Mullan Pass in Montana’s Rocky Mountains and back, according to flight-test engineers. Using this route avoids most commercial airline traffic in the region. And Moses Lake, Wash., at the halfway point, can be used for refueling or ground testing. For more difficult flights, the MAX flight-test aircraft work in concert with the telemetry room at Boeing Field. The control center provides instantaneous data and enables higher-risk testing such as flutter, or flight instability, according to Mike Torres, a flight-test engineer with Boeing Test & Evaluation. Dozens of engineers monitor different parts of the airplane, grouped in the areas they represent, such as propulsion or structural dynamics, he explained. Display screens fill a third-floor space that has frosted windows. Engineers and others see the airplane only through movement on a real-time map or by fluctuating charts and graphs that report hydraulic or engine pressure. Everyone in the room is required to wear a headset. “It allows us to be safer,” Torres said. “We can look at number changes. Now we’re always setting limits (rather than estimating).” Shannon Timke, test director with Boeing Test & Evaluation, sits in the back row of the telemetry room during the flight testing. She provides a central voice. People communicate with her and she, in turn, speaks directly to the pilots. Distractions are kept to a minimum. “The pilots are flying the airplane and that’s a lot to do; we try to reduce the workload,” Timke said. “It’s a pretty sterile environment. We try to treat it like a flight deck.” An emergency button located at each table in the telemetry room will flash a red light and sound an alarm if necessary, if data indicate a problem, and pilots then are told to stop the flight maneuver, Torres said. The first two MAX test airplanes are heavily instrumented inside the passenger cabin in order to perform aerodynamic work. The third, also filled with instrumentation, is referred to as the systems airplane, testing autopilot and other mechanisms. The fourth jet comes with a fully installed passenger interior, similar to what is found on board a commercial airliner. Flight tests also are conducted at sites in California, including at Edwards Air Force Base, to utilize longer runways. Brake testing often is done in Roswell, N.M., because the composition of the runway provides a better friction measurement. Noise testing is performed in isolated Glasgow, Mont. One of the MAX test aircraft is scheduled to fly to Farnborough, England, for the international air show in July to see how it performs in long flights over water. Keith Leverkuhn, vice president and general manager for the MAX program, said flight testing has gone very well and there have been very few “squawks,” or problem write-ups, on the test airplanes currently flying. Manufacturing is on track, with the first production MAX making its way through final assembly, he noted. Although it’s still early in testing, the MAX LEAP-1B engines are performing even better than the program had anticipated, Leverkuhn added. The engines require three markedly different test sites—sea level in Florida, intermediate altitude (5,000 to 6,000 feet, or about 1,500 to 1,800 meters) in Colorado and high-altitude (14,000 feet, or 4,300 meters) in Bolivia—with pilots putting the engines through strenuous exercises in each one, according to flight-test engineers. More difficult maneuvers are dives, stalls, flutter, zero-gravity pushovers and anything conducted close to a runway, said Craig Bomben, chief test pilot and vice president of flight-test operations. Plenty of precautions are taken. “If it’s a higher-risk test point, we make sure we have crews that have previously flown those types of maneuvers,” Bomben said. “We’ll practice in the Photo: Against a Seattle backdrop the 737 MAX conducts a test flight. The process will take the new airplane from Washington state to Bolivia before it is certified by the Federal Aviation Administration. PAUL WEATHERMAN | BOEING
Frontiers May 2016 Issue
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