Special Bulletin on Cylinder Mounting Studs for Lycoming Engines

This Special Airworthiness Information Bulletin NE-14-13 (SAIB) alerts you, owners, operators, and certificated repair facilities of Lycoming Engines of the possible failure of engine thru-studs, and/or cylinder mounting studs. The airworthiness concern is not an unsafe condition that would warrant airworthiness directive action under Title 14 of the Code of Federal Regulations (14 CFR) part 39. FAA Recommendations: 1. Inspect cylinder studs and thru-studs, for corrosion pits and missing cadmium plating. 2. Follow the cylinder installation instructions in the Lycoming overhaul manual or Lycoming Service Instruction No. 1029D. 3. Use Lycoming special tools, or their equivalent, to torque the cylinder nuts. 4. When using the special wrenches to torque cylinder nuts, ensure the wrenches do not contact the cylinder or other parts of the engine. Wrench contact can result in a correct torque indicated by the torque wrench, but the actual torque applied to the nut, and the clamping force, will be lower than required. 5. When accessible, inspect the crankcase main bearing mating surfaces for fretting. Lycoming has advised that no fretting is allowed. pdf icon NE-14-13.pdf

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