Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines, that requires a one-time acid etch inspection of the turbine exhaust case (TEC) wall between and on either side of the ``R'' and ``S'' rails in the engine mount lug area (top quadrant of the case) for the presence of weld material, and if weld material is detected, removal from service and replacement with serviceable parts. This amendment is prompted by reports of weld rework performed in the outer case wall of the TEC, in the mount lug fillet area, during original production to address local under minimum wall thickness conditions which have left the TEC's structural capability compromised. The actions specified by this AD are intended to prevent TEC structural failure under abnormal operating conditions, which could result in reduced main mount load capability, engine separation from the wing and subsequent loss of control of the aircraft.