Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires a one-time inspection to determine the material type of the stop support fittings of the main entry doors. This AD also requires repetitive visual inspections to detect cracks of certain stop support fittings of the main entry doors, and replacement of any cracked stop support fitting with a certain new stop support fitting. This amendment is prompted by reports that stress corrosion cracking was found on certain stop support fittings of the main entry doors. The actions specified by this AD are intended to detect and correct such stress corrosion cracking, which could lead to failure of the stop support fittings. Failure of the stop support fittings could result in loss of a main entry door and consequent rapid decompression of the airplane.