Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) PW2037, PW2037M, and PW2040 turbofan engines. This AD was prompted by an unrecoverable engine in-flight shutdown (IFSD) after an ice crystal icing event. This AD requires installing a software standard eligible for installation and precludes the use of electronic engine control (EEC) software standards earlier than SCN 5B/I. We are issuing this AD to correct the unsafe condition on these products.