If you’re like me, you’ve been watching the ongoing saga of Boeing and its 737 MAX. The gist of it for our purposes is that the new MAX versions of the 737 are powered by larger-diameter engines than the type was originally designed to accommodate. Since the 1980s—when Boeing switched from the type’s original low-bypass Pratt & Whitney JT8D engines to the CFM International CFM56—the reduced ground clearance when mounting high-bypass powerplants featuring improved fuel economy has required flattening the bottom of the cowlings. It was cheaper and easier than redesigning the landing gear, which is too short to accommodate the larger engines.
Seeking ever-greater fuel efficiency, Boeing equipped the 737 MAX with CFM International LEAP engines—the latest technology with an even larger diameter. To make everything fit, the company redesigned the MAX’s engine pylons to place the engines further out in front of the wing, allowing them to be mounted with appropriate ground clearance. That change in geometry apparently altered the airplane’s aerodynamics to the point that Boeing developed flight control system software—the Maneuvering Characteristics Augmentation System (MCAS)—to ensure the MAX’s handling characteristics were similar to previous models, in part to reduce airline training costs. That software apparently had flaws, though, which have been blamed for two fatal crashes under similar circumstances—and here we are, with the entire 737 MAX fleet grounded worldwide.
