The event also marks another bit of trouble for Boeing supplier Spirit AeroSystems, which is unrelated to Spirit Airlines. Spirit AeroSystems provides Boeing with the fuselages for its MAX aircraft, including doors. Last year, Spirit AeroSystems and Boeing discovered improperly drilled fastener holes in the aft pressure bulkheads of MAX fuselages. These bulkheads are dome-shaped structures at the end of the cabin. Reportedly, these defects did not cause safety issues but caused enough of an internal scandal that Spirit AeroSystems ousted its CEO. Alaska Airlines