BOEING 737 MAX REPORT THE 737]. So they did it, and did not even know what the aircraft was going to be like because they were so focused on the all-new single-aisle.” What happened, Ironically, the A320neo was launched as a defensive move. Airbus leaders wanted to blunt the threat to the A320 from the C Series, the cutting-edge Bombardier aircraft program launched and what now? in 2008 with Pratt & Whitney geared MAXSean Broderick Washington turbofan engines. Even they had no Mid-August marked five months since the last Boeing 737 MAX fleet’s idea the Neo would generate so many revenue flight and customer delivery as well as—most significantly—its new orders. second fatal accident. While Boeing is making progress on changes need- “The Neo’s success in the market- ed to convince regulators that the latest iteration of its venerable narrow- place did point out unmistakably that customers would embrace a lower body is safe to fly, the timing remains fluid. The road ahead is littered with amount of capability quickly,” McNer- unanswered questions. As for how one of the industry’s most successful ney reflected in 2012. “So that was a and best-selling models ended up grounded less than two years after en- factor. We added it all up and decided tering service, more is known. Following is a recap of how the MAX got to move with the MAX.” here, where it is headed, and—to the extent known—what comes next. The birth of the MAX took even its Some key issues related to the MAX crisis are not covered in detail. Among engine supplier by surprise. “Up until a few days before the American Air- them: detailed breakdowns of the two accident sequences as revealed in lines deal, Boeing was still saying they preliminary investigative reports. While the MAX’s Maneuvering Charac- were going to do an all-new airplane,” teristics Augmentation System (MCAS) played a role in both accidents, said former CFM executive vice pres- other concerns—from maintenance practices to the adequacy of pi- ident, GE general manager and deal lot training—will likely end up being identified as contributing factors. As broker Chaker Chahrour in 2013. “It was amazing how, literally within a few Boeing’s new MCAS software with every major accident, the lessons learned go far beyond addressing will take input from both MAX days, things had turned around.” angle-of-attack vanes—just one the primary causal factors. With two accidents to learn from, the MCAS of several changes being made may be close to being updated, but the MAX story’s influence on aircraft Where did the MCAS come from? to the flight-control system. design, certification and pilot training is only starting to be felt. Boeing’s decision to reengine the 737 STEPHEN BRASHEAR/GETTY IMAGES presented several challenges. The most significant one: how to integrate the Leap-1B engines into the design. Question: Why did Boeing develop engining of the A320 by Airbus would improvement in fuel efficiency the the prospect of losing one of its mar- probably transformative,” John Leahy, Key changes included extending the the MAX instead of a clean-sheet force Boeing to follow suit. “Not if we’re A320neo offered proved more attrac- quee customers, American Airlines. Airbus’ longtime chief salesman, re- nose gear 8 in., and cantilevering the successor to the 737? As the 2010s convinced a new airplane will be com- tive to airlines than waiting several The carrier, previously an all-Boeing called last year. “Boeing threatened to engine forward and upward of the wing began, Boeing was looking hard at ing at or near the end of the decade,” more years for an even better airplane. customer, split a record-setting order sue [American] because it all happened leading edge. developing an all-new narrowbody to then-CEO Jim McNerney told Aviation By mid-2011, seven months after the for 460 narrowbodies between the before the end of a 20-year exclusivity Early in the MAX’s development, replace the aging 737, which first flew Week in mid-2010. “I think our custom- Neo’s launch, Airbus had won more two companies—but only after Boe- agreement. But American said if Boe- Boeing discovered that the heavier en- in 1967. The company’s leaders down- ers will wait for us.” than 1,000 orders and commitments. ing agreed to launch the MAX. “The ing wanted a share of the order, they gines presented a stability and control played the belief that a rumored re- But with oil prices soaring, the 15% Boeing’s hand was finally forced by American Airlines A320neo deal was would have to produce a [reengined issue: Their larger nacelles created 737 MAX Timeline JULY 13, 2008 Bombardier JULY 20, 2011 Faced with the prospect of losing MARCH 8, 2017 NOV. 6, 2018 Boeing issues an operators’ bulletin explaining that the “er- NOV. 10, 2018 Boeing issues bulletin launches the C Series, a cutting- marquee customer American Airlines, Boeing MAX family roneous (angle-of-attack) data” can cause “the pitch trim system [to] trim the to operators with more details about the edge 110-130-seat aircraft that announces it will reengine the 737 instead of baseline, the stabilizer nose down in increments lasting up to 10 sec.” and references the MCAS and identifies the system by name. pushes into the lower end of the developing a clean-sheet successor later in the 737-8, is certified correct emergency procedures. This is the first public description of the MAX’s Many airlines issue internal bulletins to Boeing 737/Airbus A320 market. decade. American commits to 100 of them. by U.S. FAA. Maneuvering Characteristics Augmentation System (MCAS), though it is not their pilots. This is how most pilots learn referenced by name. that the MCAS exists. 2008 2010 2011 2012 2016 2017 2018 Boeing begins work on MCAS software changes DEC. 1, 2010 Airbus launches JUNE 30, 2012 Boeing JAN. 29, 2016 MAY 22, 2017 the reengined A320neo without a submits application to U.S. First flight of MAX enters service OCT. 29, 2018 Lion Air Flight 610, a NOV. 7, 2018 FAA issues emergency directive warning that data from one customer, promising a 15% gain FAA to amend type certificate the MAX, with Malaysia’s three-month-old 737-8, crashes 13 faulty AOA sensor creates “potential for repeated nose-down trim commands in fuel efficiency. A16WE to include 737-8. 737-8 1A001. Malindo Air. min. after takeoff from Jakarta, Indo- of the horizontal stabilizer.” Operators are ordered to update MAX flight nesia, killing all 189 on board. manuals to include Boeing’s Nov. 6 bulletin. The MCAS is not referenced. 30 AVIATION WEEK & SPACE TECHNOLOGY/AUGUST 19-SEPTEMBER 1, 2019 AviationWeek.com/awst AviationWeek.com/awst AVIATION WEEK & SPACE TECHNOLOGY/AUGUST 19-SEPTEMBER 1, 2019 31 BOEING 737 MAX REPORT more lift at high angles of attack (AOA) feed the left-side FCC and, if necessary, a quick-reference chart. Among its the aircraft was taxiing out, triggered source of faulty AOA data can trigger MCAS. It is still not done. and high airspeeds. Boeing’s solution: activate the MCAS. On the next flight, key steps: Hold the control column a stickshaker stall warning on the cap- 10 sec. increments of nose-down sta- So when did the world learn about Expand the 737NG’s speed trim system MCAS activation would come via data firmly and trim the aircraft using con- tain’s side as soon as the aircraft took bilizer inputs. Electric trim input will the MCAS? A Nov. 10 message from (STS) by adding the MCAS—software from the right-side (first officer’s) AOA trol-column-mounted main electric off. stop the automatic nose-down stabi- Boeing to MAX operators shed more code that expands how the horizontal vane and FCC. trim switches. If the runaway contin- Once the flaps were retracted, the lizer movement, but it “may restart” 5 light on the system described in the stabilizer is automatically adjusted as Besides adding software, managing ued, pilots could flip cutout switches on left-side FCC, reading the faulty AOA sec. after the electric trim input stops. earlier bulletin, using the MCAS’ name. the aircraft approaches its threshold the MAX’s lower pitch-down moment the center console and disconnect the data, triggered the MCAS. Nose-down The only way to stop the cycle is to Airlines disseminated bulletins to their AOA or stickshaker activation. The required another key change to the automatic trim motor. After this step, trim was applied for 10 sec. The pilots follow the runaway stabilizer checklist pilots. For most of them, it was the first resistance created by the automatic 737NG STS. On the NG, pulling back pilots would have to use the manual countered with main electric trim and toggle the console-mounted cut- time they had heard of the MCAS. nose-down stabilizer inputs would on the yoke activates a column cutout trim wheel to move the stabilizer. nose-up inputs. At least 25 automatic out switches. Boeing also warned that Still, confusion persisted. Pilots at ensure pilots felt consistent, linear switch that interrupts any automatic Because the system’s operation was stabilizer nose-down, pilot-directed “higher control forces may be needed one U.S. major airline were told by force—which FAA certification stan- stabilizer movement. But on the MAX, transparent to pilots and its trouble- stabilizer nose-up exchanges took to overcome any stabilizer nose-down their safety committee that the MCAS dards require—as they pulled back on the MCAS bypasses this switch.