Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 747-200F, 747-200C, 747-400, 747-400D, and 747- 400F series airplanes. This proposed AD would require repetitive inspections for cracking of certain fuselage internal structure, and repair if necessary. This proposed AD is prompted by fatigue tests and analysis that identified areas of the fuselage where fatigue cracks can occur. We are proposing this AD to prevent loss of the structural integrity of the fuselage, which could result in rapid depressurization of the airplane.