Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100B SUD, -300, -400, and -400D series airplanes. This proposed AD would require a one-time inspection for discrepancies of the fuselage frame to tension tie joints at body stations (BS) 1120 through 1220 and to determine if steel splice plates are installed on the fuselage frames, and related investigative and corrective actions. This proposed AD is prompted by reports indicating that severed tension ties were found at the fuselage frame joints at BS 1120 and 1140. We are proposing this AD to prevent fatigue cracking of the fuselage frame to tension tie joints, which could result in severing of the tension ties and consequent rapid decompression of the airplane fuselage.