The findings point to an ideal design: an 80-centimeter (31.4-inch) mast that’s 65 centimeters (25.4-inch) in diameter.

Despite that evidence, the blade had not been removed from service. The report also notes that since the incident, fleet-wide PW4000 inspections revealed nine more “confirmed cracked fan blades”.

The Federal Aviation Administration is requiring airlines to inspect and replace "air sealing ring" assemblies within Pratt & Whitney PW4000 low-pressure turbine [LPT] cases.