Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Stemme GmbH & Co. KG (Stemme) Models S10 and S10-V sailplanes. The proposed action would require replacing the fuel filter, inserting a revision to the Limitations Section of the airplane flight manual, and inspecting the engine valve shafts for brownish-black sticky residue. If a residue is found on the valve shafts, the proposed action would require cleaning the engine. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. The actions specified by the proposed AD are intended to prevent engine valve malfunction, which, if not corrected, could cause engine failure during flight and loss of control of the sailplane.