Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 727 airplanes. This AD was prompted by a report of cracking in the left-side chord of the fin closure rib on the vertical stabilizer. This AD requires repetitive inspections of the left and right side chords of the fin closure rib for cracking and corrosion, and related investigative and corrective actions if necessary. We are issuing this AD to detect and correct cracking and corrosion in the left- and right-side chords of the fin closure rib, which could lead to widespread cracking in the chords that might weaken the fin closure rib structure and result in loss of airplane control due to lack of horizontal stabilizer support.