Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to AlliedSignal Inc. ALF502R-5 and ALF502R-3A model turbofan engines. This proposal would require incorporation of an improved fan core inlet anti-ice system. This proposal is prompted by reports of uncommanded reduction of engine thrust (rollback) and loss of thrust control in icing conditions. The actions specified by the proposed AD are intended to prevent ice accretion on the fan core inlet stator vane surfaces, which can result in engine rollback and loss of thrust control in icing conditions.