Airworthiness Directives; Allison Engine Company 250-B and 250-C Series Turboshaft and Turboprop Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Allison Engine Company 250-B and 250-C series turboshaft and turboprop engines, that requires replacing existing beryllium copper main fuel control (MFC) bellows assemblies with Inconel 718 stainless steel welded MFC bellows assemblies. This amendment is prompted by reports of leaking MFC bellows assemblies resulting in an uncommanded minimum fuel flow condition, loss of engine fuel flow control and subsequent forced landing. The actions specified by this AD are intended to prevent MFC bellows assembly leakage, which can result in an uncommanded minimum fuel flow condition and subsequent loss of engine fuel flow control.