Operators of Teledyne Continental engines in the 470, 520 and 550 series who have installed new cylinders since November 2007 are facing a manufacturer's voluntary recall of those cylinders. TCM expects to replace some 9,600 of the cylinders, after 36 of them developed cracks in the head castings. The compromised cylinders all had more than 400 hours in service. The company has issued a mandatory service bulletin (MSB09-1) to owners to identify affected cylinders and launch replacement procedures. The cylinders are installed on some new engines and also some existing engines during full engine rebuilds or top overhauls. New cylinders will be supplied by Continental, which has established dedicated service phone numbers (U.S.: 888/200-7565; International: 251/436-8665) and a website management center at tcmlink.com/cylinders.