Airworthiness Directives; Boeing Model 727 Series Airplanes Modified in Accordance with Valsan Supplemental Type Certificate (STC) SA4363NM

This amendment revises an existing airworthiness directive (AD), applicable to Boeing Model 727 series airplanes modified by the installation of Pratt and Whitney JT8D-217C or -219 engines in accordance with Valsan STC SA4363NM, that currently requires repetitive inspections of the through-bolt nut for proper torque and for certain other conditions of the through-bolt and nut, and replacement, if necessary. That AD also requires the installation of anti-rotation plates, which constitutes terminating action for the repetitive inspections. This amendment changes the responsible office for approval of an alternative method of compliance. This amendment is prompted by the transfer of the supplemental type certificate. The actions specified in this AD are intended to prevent the nut coming off the through-bolt allowing the through-bolt to migrate out of the engine mount flange and cone bolt and possible separation of the engine.