Airworthiness Directives; Stemme GmbH & Co. KG Models S10 and S10-V Sailplanes.

This amendment adopts a new airworthiness directive (AD) that applies to certain Stemme GmbH & Co. KG (Stemme) Models S10 and S10-V sailplanes. This AD requires replacing the fuel filter if it is contaminated, inserting a revision to the Limitations Section of the flight manual, and inspecting the engine valve shafts for brownish- black sticky residue. If a residue is found on the valve shafts, this action will require cleaning the engine. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. The actions specified by this AD are intended to prevent engine valve malfunction, which could cause engine failure during flight and loss of control of the sailplane.