Airworthiness Directives; The Boeing Company Airplanes
We are superseding Airworthiness Directive (AD) 2007-16-19, which applied to certain The Boeing Company Model 747-200B, 747-300, and 747-400 series airplanes. AD 2007-16-19 required repetitive detailed inspections for cracking of the aft tension tie channels from body station (BS) 1120 to BS 1220 and from BS 880 to BS 1100, and corrective actions if necessary. AD 2007-16-19 also provided optional terminating action. This new AD retains the existing requirements, limits the area of the detailed inspection, adds repetitive surface high-frequency eddy current inspections, and mandates the previously optional terminating action. This AD was prompted by an analysis that indicated the need to mandate the previously optional modification. We are issuing this AD to prevent fatigue cracking of the tension ties, which could result in reduced structural integrity of the airplane and rapid depressurization of the airplane.