Here's what's going on with service bulletins from Textron Aviation this week.
SEL-71-16 & MEL-71-05 which applies to all Columbia/Cessna TTx aircraft, as well as Twin Cessna 404, 411, 411A, 421, 421A, 421B, 421C. This bulletin simply transmits Continental SIL21-04B. Both bulletins announce the long awaited arrival of an OEM silicone valve cover gasket solution for cross flow cylinders found on most 550 engines today. Order your silicone gaskets from Air Power today at this LINK. Textron deems this to be an optional service bulletin.
SEL-24-11 & MEL-24-04 are a transmittal of Continental CSB19-06, released in 2019. Most affected aircraft are likely already in compliance with CSB19-06, but it's worth your time to verify. These bulletins apply to all Columbia/Cessna TTx aircraft, many Beechcraft Bonanza models, and twin Cessna T310, 320, 335, 340A, 401, 402, 411, 414, 421. Textron deems this to be a mandatory service bulletin.