Action
Final rule.
Summary
We are superseding Airworthiness Directive (AD) 84-19-01 for certain The Boeing Company Model 747-100, 747-200B, and 747-200F series airplanes. AD 84-19-01 required repetitive inspections for cracking of certain tension ties, and repair and certain modifications if necessary. This new AD requires, for certain airplanes, additional inspections for cracking of the tension tie at body station (BS) 760 or 780, corrective action if necessary, and eventual modification of the tension ties. For all airplanes, this new AD requires repetitive post- modification inspections for cracking of the tension tie at BS 760 or 780, and corrective action if necessary. This AD was prompted by reports of cracking in the BS 760 tension tie as a result of bending due to cabin pressurization. We are issuing this AD to detect and correct tension tie cracking, which could eventually result in in- flight depressurization of the airplane and the inability to withstand current regulatory failsafe loads.