First, it has not been a requirement to overhaul ANY piston engines operated under Part 135, every (5) Calendar years. It has always been the TBO set by the manufacturer, and very few have a Calendar Year limit. I don't know of any less than 10 years, which is somewhat reasonable. In fact, some are known to be approved for 'on-condition' up to extended TBO limits - several Lycomings fall into this category. Having to overhaul both TIO-540-J2BD's off a Piper Navajo Chieftain that only flies 200 hours a year, with engines remanned 5 years ago, and only 1,000 hours on the motors, is asinine. That's a $100,000. proposition... every five years! I know of some round engines that have a TBO of 1,600 hours, that have been flying Part 135 on the same planes for 15 years. So, a Five Calendar Year Limit, would be a NEW thing. A very expensive new thing for 135 operators.
Second, I didn't mean to offend anyone here. I only posted in the 135 and Maintenance forums to find someone with an answer. A person in the maintenance forum might not always look in a 135 forum, or vice versa. Just trying to keep my head above water. Thank you for the replies, just the same.
Sheeezz, Avbug, what are you, the site moderator or something? The question was, "Is the FAA going to reduce any piston engine TBO limits on FAR Part 135 planes to (5) Calendar Years?" Instead of chastising and belittling someone you don't really know the experience of, and rehashing the obvious about general engine operations just to hear yourself spew, your answer should be... "Geeez, I don't have friggin' a clue." Because, it's obvious that you don't.