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The Boeing 737 MAX is the fourth generation of the Boeing 737, a narrow-body, twinjet airliner manufactured by Boeing . It succeeds the Boeing 737 Next Generation and was designed to rival the Airbus A320neo Family. The 737 MAX is based on the typical Boeing 737 design. Major improvements on the MAX include the CFM Internation LEAP-1B engines, aerodynamic changes, airframe modifications and its distinctive split-tip winglets. This aircraft was announced on August 30, 2011. Its maiden flight was on January 29, 2016 and was certified by the Federal Aviation Administration (FAA) in March 2017. The first delivery was a MAX 8 to Malindo Airways in May 2017. It commenced service on May 22, 2017.

Boeing 737 MAX

Variants[]

Boeing offers 4 variants of the 737 MAX, offering 138 to 204 seats in typical two-class configuration and a range of 3,215 to 3,825 nmi (nautical miles):

  • 737 MAX 7
  • 737 MAX 8
  • 737 MAX 9
  • 737 MAX 10

The MAX 7, MAX 8 and MAX 9 are intended to replace the 737-700, 737-800 and 737-900 respectively. The MAX 10 is a further-stretched model.


Development[]

Background[]

In 2006, Boeing started considering the replacement of the 737 with a "clean-sheet" design that could follow the Boeing 787 Dreamliner. In June 2010, the decision on this replacement was postponed to 2011.

On December 1, 2010, Boeing's rival, Airbus launched the Airbus A320neo Family, which improved fuel burn and operating efficiency with new engines: CFM Internation LEAP and the Pratt & Whitney PW1000G. In February 2011, Boeing's CEO Jim McNerney maintained "We're going to do a new airplane." In March 2011, Boeing Commercial Airplanes' (BCA) President James Albaugh told participants of a trade meeting the company was not sure about a 737 re-engine, like Boeing CFO James A. Bell stated at an investor conference the same month. The Airbus A320neo gathered 667 commitments at the June, 2011 Paris Air Show for a backlog of 1,029 units since its launch, setting an order record for a new commercial airliner

Program Launch[]

On August 30, 2011, Boeing's board of directors approved the launch of the re-engines 737, expecting 4% lower fuel burn than the Airbus A320neo. Studies for additional drag reduction were performed during 2011, including revised tail cone, natural laminar flow nacelle and hybrid laminar flow vertical stabiliser. Boeing abandoned the development of the new design. Boeing expected the 737 MAX to meet or exceed the range of Airbus A320neo. Firm configuration for the 737 MAX was scheduled for 2013.

In March 2010, the estimated cost to re-engine the 737, according to Mike Bair, BCA's vice president of business strategy and marketing would be US$2-3 billion, including the CFM engine development. During Boeing's Q2 2011 earnings call, former CFO James A. Bell said the development cost for the airframe only would be 10-15% of the cost of a new program estimated at US$10-12 billion at the time. Bernstein Research predicted in January 2012, that this cost would be twice that of the A320neo. The MAX development cost could have been well over the internal target of US$2 billion, and closer to US$4 billion. Fuel consumption is reduced by 14% from the 737 Next Generation. Southwest Airlines was signed up as the launch customer in 2011.

In November 2014, McNerney said the 737 would be replaced by a new airplane by 2030, probably using composite materials — that would be slightly bigger and have new engines, but would retain the 737's general configuration.

Production[]

On August 13, 2015, the first 737 MAX fuselage completed assembly at Spirit Aerosystems in Wichita, Kansas, for a test aircraft that would eventually be delivered to launch customer Southwest Airlines. On December 8, 2015, the first 737 MAX — a MAX 8 named Spirit of Renton — was rolled out at the Boeing Renton Factory.

Because GKN could not produce the titanium honeycomb inner walls for the thrust reversers quickly enough, Boeing switched to a composite part produced by Spirit to deliver 47 MAXs per month in 2017. Spirit supplies 69% of the 737 airframe, including the fuselage, thrust reverser, engine pylons, nacelles, and wing leading edges.

A new spar-assembly line with robotic drilling machines should increase throughput by 33%. The Electroimpact automated panel assembly line sped up the wing lower-skin assembly by 35%. Boeing planned to increase its 737 MAX monthly production rate from 42 planes in 2017, to 57 planes by 2019. The new spar-assembly line is designed by Electroimpact. Electroimpact has also installed fully automated riveting machines and tooling to fasten stringers to the wing skin.

The rate increase strained the production and by August 2018, over 40 unfinished jets were parked in Renton, awaiting parts or engine installation, as CFM engines and Spirit fuselages were delivered late.[40] After parked airplanes peaked at 53 at the beginning of September, Boeing reduced this by nine the following month, as deliveries rose to 61 from 29 in July and 48 in August.[41]

On September 23, 2015, Boeing announced a collaboration with COMAC to build a completion and delivery facility for the 737, in Zhoushan, China, the first outside the United States. This facility initially handles interior finishing only, but will subsequently be expanded to include paintwork. The first aircraft was delivered from the facility to Air China on December 15, 2018.

The largest part of the suppliers cost are the aerostructures with US$10–12M (35-34% of the US$ 28.5-35 M total), followed by the engines with US$7–9M (25-26%), systems and interiors with US$5–6M each (18-17%), then avionics with US$1.5–2M (5-6%).

Flight Testing and Certification[]

The first flight took place on January 29, 2016, at Renton Municipal Airport, nearly 49 years after the maiden flight of the original 737-100, on April 9, 1967. The first MAX 8, 1A001, was used for aerodynamic trials: flutter testing, stability and control, and takeoff performance-data verification, before it was modified for an operator and delivered. 1A002 was used for performance and engine testing: climb and landing performance, crosswind, noise, cold weather, high altitude, fuel burn and water-ingestion. Aircraft systems including autoland were tested with 1A003. 1A004, with an airliner layout, flew function-and-reliability certification for 300h with a light flight-test instrumentation.

The 737 MAX gained Federal Aviation Administration (FAA) certification on March 8, 2017. It was approved by EASA on March 27, 2017. After completing 2,000 test flight hours and 180-minute ETOPS testing requiring 3,000 simulated flight cycles in April 2017, CFM International notified Boeing of a possible manufacturing quality issue with low pressure turbine (LPT) discs in LEAP-1B engines. Boeing suspended 737 MAX flights on May 4, and resumed flights on May 12.

During the certification process, the FAA delegated many evaluations to Boeing, allowing the manufacturer to review their own product. It was widely reported that Boeing pushed to expedite approval of the 737 MAX to compete with the Airbus A320neo, which hit the market nine months ahead of Boeing's model.

Introduction[]

The first delivery was a MAX 8, handed over to Malindo Air (a subsidiary of Lion Air) on May 16, 2017; it entered service on May 22. Norwegian Air International was the second airline to put a 737 MAX into service, when it performed its first transatlantic flight with a MAX 8 named Sir Freddie Laker on July 15, 2017, between Edinburgh Airport in Scotland and Bradley International Airport in the U.S. state of Connecticut.

Boeing aimed to match the 99.7% dispatch reliability of the 737 Next Generation (NG). Southwest Airlines, the launch customer, took delivery of its first 737 MAX on August 29, 2017. Boeing planned to deliver at least 50 to 75 aircraft in 2017, 10–15% of the more than five hundred 737s to be delivered in the year.

After one year of service, 130 MAXs had been delivered to 28 customers, logging over 41,000 flights in 118,000 hours and flying over 6.5 million passengers. flydubai observed 15% more efficiency than the NG, more than the 14% promised, and dependability reached 99.4%. Long routes include 24 over 2,500 nmi (4,630 km), including a daily Aerolineas Argentinas service from Buenos Aires to Punta Cana over 3,252 nmi (6,023 km).

In 2019, Moody's had estimated Boeing's operating margin to be US$12–15 million for each 737 Max 8 at its list price of $121.6 million, although the list price is usually discounted 50-55% in practice. This high margin was made possible by the efficiencies of production volume and the amortization of development costs and capital investment over the decades of the program run. However, costs have since risen significantly and the margin reduced following the second crash, the FAA grounding, and the severe disruption to production. Boeing estimated it would cost an additional $6.3 billion to produce the remaining 737 MAX program, $4 billion for "future abnormal costs" as production restarted, plus an estimated $8.3 billion for concessions and compensation to customers. The rising costs also led Moody's to downgrade Boeing's credit rating.

Grounding[]

In 2019, the Boeing 737 MAX was grounded worldwide, after a malfunctioning flight control system caused two new aircraft to crash in Indonesia and Ethiopia, killing all 346 people on board. In the twenty months during the grounding, Boeing redesigned the computer architecture that supported the Maneuvering Characteristics Augmentation System (MCAS), while investigations faulted aircraft design and certification lapses. Boeing faces legal and financial consequences, as no deliveries of the MAX could be made while the aircraft was grounded, and airlines canceled more orders than Boeing produced during this period; a portion of those aircraft have lost their original buyers. Boeing found foreign object debris in the fuel tanks of 35 of 50 grounded 737 MAX aircraft that were inspected, and is to check the remainder of the 400 undelivered planes. Boeing had similar issues with 787s produced in South Carolina. The FAA curtailed Boeing's delegated authority, and invited global aviation stakeholders to comment on pending changes to the aircraft and to pilot training. The FAA grounding order was lifted in 2020; all aircraft must be repaired to comply with various airworthiness directives.

After being charged with fraud in connection of both crashes of the 737 MAX, Boeing settled to pay over $2.5 billion: a criminal monetary penalty of $243.6 million (10%), $1.77 billion of damages to airline customers (70%), and a $500 million crash-victim beneficiaries fund (20%).

Design[]

In mid-2011, one design objective was matching fuel burn of the 737 MAX to that of the Airbus A320neo's 15% fuel-burn advantage. The initial 737 Max reduction was 10–12%; it was later enhanced to 14.5%. The fan was widened from 61 in (150 cm) to 69.4 in (176 cm) by raising the nose gear and placing the engine higher and forward. The split tip winglet added 1–1.5% fuel burn reduction and a re-lofted tail cone another 1%. Electronically controlling the bleed air system improved efficiency. The new engine nacelle included chevrons, similar to those of the Boeing 787, which also helped to reduce engine noise.

Aerodynamic Changes[]

The split tip wingtip device is designed to maximize lift while staying in the same ICAO Aerodrome reference code letter C gates as current Boeing 737s. It traces its design to the McDonnell Douglas MD-12 1990s twin-deck concept, proposed for similar gate restrictions before the Boeing merger. A MAX 8 with 162 passengers on a 3,000 nmi (5,600 km) flight is projected to have a 1.8% better fuel burn than a blended-winglet-equipped aircraft and 1% over 500 nmi (930 km) at Mach 0.79. The new winglet is 9 ft 6 in (2.90 m) in total height.

Aviation Partners offers a similar "Split-Tip Scimitar" winglet for previous 737NGs.[107] It resembles a three-way hybrid between a blended winglet, wingtip fence, and raked wingtip.

Other improvements include a re-contoured tail cone, revised auxiliary power unit inlet and exhaust, aft-body vortex generators removal, and other small aerodynamic improvements.

Structural and other changes[]

The 8 inches (20 cm) taller nose-gear strut maintains the same 17-inch (43 cm) ground clearance of the previous 737 engine nacelles. New struts and nacelles for the heavier engines add bulk, the main landing gear and supporting structure have been reinforced, and fuselage skins are thicker in some places which add 6,500 lb (2,900 kg) to the MAX 8's empty aircraft weight. To preserve fuel and payload capacity, its MTW is 7,000 lb (3,200 kg) heavier.

Rockwell Collins selected to supply four 15.1-inch (3.8 cm) landscape LCDs, similar to the ones used in the 787 Dreamliner. This was done to improve pilots' situation awareness and efficiency. Boeing plans to avoid major changes in the flight deck of the 737 MAX to maintain commonality with the 737NG family. Boeing Commercial Airplanes CEO Jim Albaugh said in 2011, that adding more fly-by-wire control systems would be "very minimal", although the 737 MAX's extended spoilers are fly-by-wire (FBW) controlled.

In addition to the Speed Trim System (STS), the automatic stabilizer control system has been enhanced to include MCAS. Compared to STS, MCAS has greater authority and cannot be disengaged with the aft and forward column cutout switches. The center console stabilizer-trim cutout switches have been re-wired. Unlike previous versions of the 737, the automatic stabilizer trim control functions cannot be turned off while retaining electric trim switches functionality.

The MCAS system was deemed necessary by Boeing to meet its internal objective of minimizing training requirements for pilots already qualified on the 737NG. MCAS was to automatically mitigate the pitch-up tendency of the new flight geometry due to the engines being located further forward and higher than on previous 737 models.During a reassessment of the aircraft in February 2020, both FAA and EASA determined that the stability and stall characteristics of the plane would have been acceptable with or without MCAS.

The 737 MAX features the Boeing Sky Interior with overhead bins and LED lighting as standard, which is based on the 787's interior.

Engines[]

In 2011, the LEAP-1B was initially 10-12% more efficient than the previous 156 cm (61 inches) CFM56-7B of the 737NG. This engine has 18 blades made of woven carbon fibre, which enables a 9:1 bypass ratio (up from 5.1:1 with the previous 24-blade titanium fan) for a 40% smaller noise footprint. The CFM56 bypass ranges from 5.1:1 to 5.5:1. The two-spool design has a low-pressure section comprising the fan and three booster stages driven by five axial turbine stages and a high-pressure with a 10-stage axial compressor driven by a two-stage turbine. The 41:1 overall pressure ratio increased from 28:1 and advanced hot-section materials with higher operating temperatures permit a 15% reduction in thrust-specific fuel consumption (TSFC). This reduces the carbon emission by 20%, nitrogen oxides by 50% although each engine weighs 849 lb (385 kg) more. Total weight of each engine is 6,129 lb (2,780 kg).

In August of 2011, Boeing had to choose between 66 inches (168 cm) or 68 inches (173 cm) fan diameters necessitating landing gear changes to maintain a 17-inch (43 cm) ground clearance beneath the new engines. Boeing Commercial Airplanes CEO James Albaugh stated "With a bigger fan you get more efficiency because of the bypass ratio BUT ALSO an increase in weight and drag", implementing more airframe changes.

In November 2011, Boeing selected the larger fan diameter, necessitating a 6-8 in (150 - 200 mm) longer nose landing gear. In May of 2012, Boeing further enlarged the fan to 69.4 inches (176 cm), paired with a smaller engine core within minor design changes before the mid-2013 final configuration.

The nacelle features chevrons for noise reduction like the 787. A new bleed air digital regulator will improve its reliability.The new nacelles being larger and more forward possess aerodynamic properties which act to further increase the pitch rate. The larger engine is cantilevered ahead of and slightly above the wing, and the laminar flow engine nacelle lipskin is a GKN Aerospace one-piece, spun-formed aluminum sheet inspired by the 787.

Orders and Deliveries[]

[Airlines] was 737 MAX's first disclosed customer. By November 17, 2011, there were 700 commitments from nine customers, including Lion Air and SMBC Aviation Capital. By December, 2011, the 737 MAX had 948 commitments and firm orders from 13 customers. On September 8, 2014, Ryanair agreed to 100 firm orders with 100 options. In January 2017, aircraft leasing company GECAS ordered 75. By January 2019, the 737 MAX had 5,011 firm orders from 78 identified customers, with top three being [Airlines] with 280, flydubai with 251 and Lion Air with 251. The first 737 MAX 8 was delivered to Malindo Air on May 16, 2017.

Following the groundings in March 2019, Boeing suspended all deliveries of 737 MAX aircraft, reduced production from 52 to 42 aircraft per month, and on December 16, 2019, announced that production would be suspended from January 2020 to conserve cash and prioritize delivery of the 387 aircraft in storage once recertified. At the time of the grounding, the 737 MAX had 4,636 unfilled orders valued at an estimated $600 billion. By November 30, 2020, at the time of the ungrounding, the unfilled orders stood at 4,039 aircrafts. As of September 2021, the 737 MAX has 4,024 unfilled orders and 581 deliveries.

Boeing 737 MAX Orders and Deliveries Data[]

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 TOTAL
Orders 150 914 708 891 410 540 744 824 -136 -529 59 4,605
Deliveries 74 256 57 27 167 581
  • Production halted between January and late May 2020, currently in low-rate production.
  • In 2019, there were 47 orders with 183 cancellations of the 737 MAX.
  • In 2020, there were 112 orders with 641 cancellations of the 737 MAX.
  • As of September 2021, there were 575 orders with 516 cancellations of the 737 MAX

Note: The above table is limited to only the information available. It'll be updated once more information is available.

Accidents and Incidents[]

Between March 2017 and March 2019, the global fleet of 387 aircrafts operated 500,000 flights and experience 2 fatal incidents, having an accident rate of four accidents per million flights before it was grounded. The previous Boeing 737 generations averaged 0.2 accidents per million flights.

Combined, the two fatal incidents killed all 346 people on board.

Lion Air Flight 610 crash site

Lion Air Flight 610[]

On October 29, 2018, Lion Air Flight 610, 737 MAX 8 registration PK-LQP, plunged into the Java Sea approximately 13 minutes after takeoff from Soekarno-Hatta International Airport, Jakarta, Indonesia. The a flight was a scheduled domestic flight to Depati Amir Airport, Pangkal Pinang, Indonesia. All 189 people on board died. This was the first fatal aviation accident and first hull loss of the 737 MAX. The aircraft had been delivered to Lion Air two months prior to the crash. People familiar with the investigation reported that during a flight piloted by a different crew on the day before the crash, the same aircraft experienced a similar malfunction but an extra pilot sitting in the cockpit jumpseat correctly diagnosed the problem and told the crew how to disable the malfunctioning MCAS flight-control system. Indonesia's National Transportation Safety Committee released its final report into the accident on October 25, 2019, attributing the crash to the MCAS pushing the aircraft into a nose-dive due to data from a faulty angle-of-attack sensor. Following the Lion Air crash, Boeing issued an operational manual guide advising airlines on how to address erroneous cockpit readings.

Ethiopian Airlines Flight 302 crash site

Ethiopian Airlines Flight 302[]

On March 10, 2019, Ethiopian Airlines Flight 302 , a 737 MAX 8 registration ET-AVJ, crashed approximately 6 minutes after takeoff from Addis Ababa, Ethiopia. Ethiopian Airlines Flight 302 was a scheduled flight to Nairobi, Kenya. The crash killed all 149 passengers and 8 crew members on board. The aircraft was 4 months old at that time. The cause of the crash was initially unclear, though the aircraft's vertical speed (V/S) after takeoff was reported to be unstable. Evidence retrieved on the crash site suggests, that at the time of the crash, the aircraft was configured to dive, similar to Lion Air Flight 610. On April 4, Ethiopian transport minister Dagmawit Moges stated, that the crew "performed all the procedures repeatedly provided by the manufacturer but was not able to control the aircraft."

The subsequent findings in the Ethiopian Airlines crash and the Lion Air crash led to the global 737 MAX groundings. On August 19, 2019, Forbes estimated that the 737 MAX would not resume service before 2020.

Specifications[]

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