JUNE 2020: Boeing begins a series of long-delayed flight tests of its redesigned 737 MAX with regulators at the controls. APRIL 2021: Boeing halts 737 MAX deliveries after electrical problems re-ground part of the fleet. JULY 2023: Boeing's first delivery of the 737 MAX 7 is delayed to 2024. AUGUST 2023: Boeing identifies a new 737 MAX supplier quality problem involving improperly drilled holes on the aft pressure bulkhead. SEPTEMBER 2023: Boeing 737 MAX deliveries fall to their lowest levels since August 2021.