The Boeing 737 MAX is the fourth generation of Boeing’s best selling 737 narrow-body aircraft series. It was launched in 2011 to counter Airbus’s A320neo series and entered service in 2017. The MAX introduced several major design changes compared to preceding 737 models, including more efficient CFM LEAP engines, improved aerodynamics such as new split tip winglets, and airframe modifications. However, there were issues with the Maneuvering Characteristics Augmentation System (MCAS) flight control software, which led to two fatal crashes and the subsequent grounding of the MAX fleet worldwide from 2019 to 2020.
LEAP engines bring improved fuel efficiency
The 737 MAX is powered by CFM International LEAP high bypass turbofan engines. Compared to previous CFM56 engines, the LEAP provides 10-15% better fuel efficiency, as well as reduced emissions and noise footprint. Key improvements include an increased bypass ratio enabled by the new 18-blade carbon fiber composite fan, and the use of advanced hot section materials for higher operating temperatures.
Modifications change aircraft aerodynamics
Aerodynamic improvements on the MAX include the distinctive new split tip winglets, a re-contoured tail cone, vortex generator removal, and other changes. However, repositioning the engines higher and further forward affected the aerodynamic handling, which Boeing tried to compensate for with the problematic MCAS software.
Structures reinforced to support larger engines
The MAX’s larger and heavier LEAP engines required reinforcements to the aircraft structures. Changes include taller nose gear, reinforced main landing gear, thicker fuselage skin panels, and an increase in maximum takeoff weight to maintain capacity.
MCAS intended to enhance aircraft handling
The Maneuvering Characteristics Augmentation System (MCAS) was a flight control software function introduced on the MAX to counter aircraft handling changes from the engine repositioning. It was intended to improve pitch stability but technical flaws led to improper activations, causing two deadly crashes.
In summary, the 737 MAX introduced major engine, aerodynamic and structural upgrades over earlier 737s for efficiency, but issues with the MCAS software led to the worst crisis in Boeing’s history.