Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for certain Boeing Model 747 series airplanes. That AD currently requires a one-time inspection to determine the material type of the stop support fittings of the main entry doors (MEDs). That AD also currently requires repetitive detailed inspections to detect cracks of certain stop support fittings of the MEDs, and replacement of any cracked stop support fitting with a certain new stop support fitting. This proposed AD would add new inspections and replacement if necessary of the stop support fittings of MED 3, and add airplanes to the applicability. This proposed AD is prompted by reports of MED 3 having certain stop support fittings which are susceptible to stress corrosion cracking. We are proposing this AD to detect and correct stress corrosion cracking of the stop support fittings of the MEDs, which could result in damage to the adjacent forward edge frame of the door and consequent loss of a MED andrapid decompression of the airplane.