Airworthiness Directives; Boeing Model 737 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737 series airplanes, that requires repetitive ultrasonic inspections to detect broken bolts that attach the terminal support fittings to the upper part of the Body Station 1088 bulkhead, and corrective actions, if necessary. This amendment also requires eventual replacement of the existing bolts with new, improved bolts, which, when accomplished, terminates the repetitive inspection requirements of this AD. This amendment is prompted by reports that bolts that attach the terminal support fittings to the upper part of the bulkhead were found broken. The actions specified by this AD are intended to prevent such broken bolts, which could result in reduced structural integrity of the vertical fin installation and possible loss of the vertical fin.