One of two sensors that measures the angle of attack is pictured at bottom on a Boeing 737 Max 8 airplane outside the company's factory on March 22, 2019 in Renton, Wash. The sensor and associated software are at the center of a safety investigation after two deadly 737 Max crashes, and an FAA bulletin issued Aug. 14 stresses the need to avoid damaging the sensors. (Stephen Brashear/Getty)