Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

This amendment rescinds Airworthiness Directive (AD) 98-23-07, which is applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines. That AD requires a one-time acid etch inspection of the turbine exhaust case (TEC) wall between and on either side of the ``3R'' 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. The requirements of that AD were 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 airplane. Since the issuance of that AD, the FAA received reports from the manufacturer that describe a new safety analysis that determines the acid etch inspection for weld material is unnecessary.