An additional 200 hours can be added to engines used in frequent service, accumulating 40 hours or more per month. This addition, published in Note 11 in SI No. 1009BA, has already been in effect. There is also a previous provision capable of extending the 12-year limit through a corrosion inspection by a mechanic with an Inspection Authorization. The published TBO intervals do not apply to engines that have been operated outside of Lycoming’s published specifications.