Airplanes seem to be coming apart in midair. An Alaska Airlines flight was disrupted when the door plug on a section of its fuselage broke off after takeoff. The airplane model, Boeing 737 Max, has been under scrutiny since airplane crashes dating to 2018 and 2019. Investigators determined the cause as a door plug that failed. Other investigations have found loose bolts on 737 Max planes that could be the cause of the door plug failure. Consequently, the Federal Aviation Administration grounded the nation’s Boeing 737 9 Max fleet, citing safety concerns. United Airlines owns and operates 79 su…