Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT8D series turbofan engines, that requires inspections of main fuel pump control shafts for excessive spline wear. Additionally, as terminating action to the inspections, this action requires the replacement of the main fuel pump control shaft with parts of improved design, and reworking the main fuel pump impeller, impeller gear train plate assembly, and impeller cover assembly. This amendment is prompted by reports of failed main fuel pump control shafts caused by excessive spline wear. The actions specified by this AD are intended to prevent loss of engine throttle control, uncommanded acceleration, uncommanded deceleration or inflight shutdown, which could result in reduced airplane control during a critical phase of flight.