Airworthiness Directive · Amendment 39-10284 · Boeing Model 747 Series Airplanes Equipped with Pratt & Whitney JT9D-3 and -7 Series Engines
Boeing Model 747 Series Airplanes Equipped with Pratt & Whitney JT9D-3 and -7 Series Engines
Model 747 series airplanes; as listed in Boeing Alert Service Bulletin 747-54A2069, Revision 9, dated May 29, 1997; certificated in any category.
This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires repetitive inspections for discrepancies of the forward engine mount bulkhead of the nacelle strut, and corrective action, if necessary. That AD also provides for optional terminating action for the repetitive inspections. For certain airplanes, this amendment adds repetitive inspections for discrepancies in the forward engine mount bulkhead and in the forward lower spar web, and corrective actions, if necessary. For other airplanes, this amendment adds a one- time inspection to detect stop drilled cracks of the exterior of the forward engine mount chord, and replacement of the chord with a new chord, if necessary. This amendment also adds an additional optional terminating action for the repetitive inspections. This amendment is prompted by reports that fatigue cracking was found in an area adjacent to the inspection area specified in the existing AD. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could lead to the failure of the forward engine mount bulkhead and consequent separation of the engine from the airplane.
