This SAE Aerospace Information Report (AIR) provides information on anti blow-by design practice for cap seals. Suggestions for piston cap seal sidewall notch design and other anti blow-by design details are also described. It also includes information on two key investigations based on the XC-142 as part of the text and as Appendix A.
Revision C to AIR1243 is a general update of the document with added Caution 2 in Section 8. Drawings have been added to Appendix A.