Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Pratt & Whitney JT8D series turbofan engines. This proposal would require inspections of main fuel pump control shafts for excessive spline wear. Additionally, as terminating action to the inspections, this proposal would require 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 proposal is prompted by reports of failed main fuel pump control shafts caused by excessive spline wear. The actions specified by the proposed 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.