Having now flown close to 300 test flights with four flight test airplanes, Boeing says its 737 Max 8 program remains firmly on schedule as company engineers work to close testing on the first airplane by the end of September. Scheduled for certification and entry into service during the third quarter of 2017, the airplane has executed a virtually flawless flight-test campaign, according to company executives, placing it in a solid position to fulfill Boeing's “Right at First Flight” mantra.
Speaking to reporters at Boeing’s Seattle Flight Test Center last month, 737 Max chief project engineer Michael Teal explained that Boeing has performed most of the program’s stability and control work, including handling characteristics and flutter testing with the first flight test article.
The second airplane, described by Teal as one of the program’s propulsion airplanes, started life performing nautical air fuel mileage tests and since has finished its flight loads survey. It also performed high-altitude testing in La Paz, Bolivia. “There’s been no drama around here,” said Teal. “The testing has been going very well. It’s been hitting the expectations so we’re very happy with how it’s going.”
At the time of his briefing, mechanics had just removed engine instrumentation for thrust-versus-drag calculations and schedules called for it to go to Montana next for community noise testing.
Boeing uses the third airplane, said Teal, mainly for propulsion and systems work such as autoland and head-up display testing, as well as engine drainage tests.
Here at the Farnborough International Airshow, the fourth test airplane is participating in the show’s flying displays. That airplane, equipped with much of the new interior for launch customer Southwest Airlines, performs the program’s environmental testing, including smoke and Halon detection. After the show, Boeing plans to take it to Russia for cold weather testing.
“It’s also an airplane we’re doing customer work on,” said Teal. “In our Right at First Flight initiative, we’re working on what we call ‘fly like the airlines.’ In two days, we did eight simulated flights. We’d fly for an hour and a half, we’d land, and then we’d pretend we taxied in and then we would do all the ground checks, we’d turn the engines off, we’d fuel it, we’d do any maintenance an airline would typically do on the ground during a thirty minute turn, then we’d start the engines and take back off.”
Boeing intended to effectively de-bug the airplane with the exercise, explained Teal, thereby ensuring the airplane is customer-ready upon delivery. “That testing was very successful,” he said. “We did find a couple of, I’ll call them squawks, but that’s what you want to find and it turned out that the two that we found we already had on our list of things we had to fix.”
Now flying with CFM Leap-1B compliance engines, airplanes two, three and four will eventually get fitted with final delivery engines that have new low-pressure compressors (LPC). Those engines, which Teal said would start arriving around August, will require what he characterized as some minor additional testing.
Last year CFM discovered the need to modify the LPC to improve stall margin. With the original engines, Boeing has to use suboptimum bleed schedules, leaving the bleeds open more than desired for the best possible fuel efficiency. “We want the bleeds closed for better fuel mileage,” explained Teal. “We could have certified and delivered these engines, but we wanted the best engines. So in the ones we’re flying now the bleeds are opened a little bit more than we desire, but when the final Block 2s come in and we get the final bleed schedules, and that will determine the final configuration.”
Once the team returns to Seattle from Farnborough, plans call for the function and reliability testing to start with the final delivery engines installed on the third and fourth airplanes and finish in the fourth quarter, likely in October or November.
Meanwhile, Boeing continues building production Max 8s at a rate of one per month, and will continue to do so until first delivery to Southwest. By the end of last month, two production airplanes sat outside the Renton factory painted in Southwest colors and another two underwent final assembly inside. While those airplanes also await installation of the Block 2 engines, Teal expects them to require minimal change incorporation. “We’ve put a plan together of how much we forecast the change incorporation,” said Teal. “Right now we are considerably under our forecast, so I’m very happy with that,” he concluded.
Separately, Boeing during the third week of June released 90 percent of the drawings for the next variant, the 737 Max 9. The company has already started building stringers for the first Spirit Aerosystems-supplied fuselage and plans to start the first wing build in September. Schedules call for rollout and first flight by the end March 2017.