The US aviation authority on Monday said it found “multiple” issues with aircraft maker Boeing’s production practices during an investigation launched after a fuselage panel blew out mid-air on a 737 MAX flight. The Federal Aviation Administration (FAA) said it found “multiple instances” where Boeing and parts supplier Spirit AeroSystems “allegedly failed to comply with manufacturing quality control requirements.” “The FAA identified non-compliance issues in Boeing’s manufacturing process control, parts handling and storage, and product control,” the US regulator said, adding that the investig…