AD Requested To Require Camshaft Gear Replacement Continental Motors’ recently issued Mandatory Service Bulletin MSB05-8B calling for preemptive replacement of cam gears in Continental 520- and 550-series engines (plus a few IO-470s). The MSB calls for tearing down engines with older-style camshaft gears within the next 100 hours in service, or within 12 years of when the engine was built, rebuilt or overhauled (whichever comes first), and replacing the older-style camshaft gear with a new thicker gear (part number 656818).
Source: aero newsContinental Mandatory Service Bulletin MSB05-8B Could Have A Long Reach