Calendar TBO Limits

FreightPup

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A mechanic recently told me that he'd heard that the FAA is now going to require piston aircraft operated under FAR Part 135, to have their engines overhauled at TBO (or) 5 Calendar Years, which ever comes first. This is ludicrous! Has anyone heard, or know of anything about this, or is it a hoax? Apparently there was some concern over rust and internal corrosion build up with operators who aren't flying much.
 

deadstick

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The manufacturer sets the TBO by model, but based on time (tach, etc) or time in service. How can "one size fit all?"

I think the 520 is 12 years right now. Aren't props 6 years, now?
 

avbug

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Learn to post in one forum. Do not spam multiple forums with the same question or post.

This isn't a new requirement, it's an existing one. It isn't five years, however. TBO isn't simply spelled out in terms of operating hours or cycles. Time Between Overhaul is also spelled out in years, and many powerplants have year limitations which must be respected under Part 135. A 12 year limit on many piston powerplants, for example, means that if the engine hasn't been flown in the past 12 years it's still due for an overhaul. Many propellers have similiar TBO limits on them, usually at shorter intervals of three or five years.

Think about it this way: piston engines need regular oil changes. Typically 25 or 50 hours are used as oil change intervals. However, oil should also be changed every 3-4 months, even if the airplane doesn't fly at all. Acids wash off case walls, acids sit in the oil around bearings and races and parts subject to corrosion, and the oil in your airplane and in your car needs to be changed regularly...even if the engine is never run. Both time limits (in hours, or for your car usually in miles or kilometers) and calendar limits apply to many aspects of maintenance.

Many inspections, airworthiness directives, and required maintenance is done on both a calendar and on a time or cycle basis, and this includes overhaul of piston engines. This is not a new requirement...it's in effect now.

This doesn't apply to aircraft engines operated under part 91...where one can fly beyond TBO and operate "on-condition."
 

brokeflyer

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he can post im multiple forums....it is stupid not to. That is the best way to find all opinions and determine what is fact.

relax avbug.
 

FreightPup

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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.
 

avbug

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In fact, some are known to be approved for 'on-condition' up to extended TBO limits - several Lycomings fall into this category.
Not under Part 135, they're not.

Certain operators are given TBO extensions in small increments, which apply to those operators under their maintenance and inspection programs.

Under 135, calendar limits and time limits become mandatory unless a specific extension is authorized.

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.
Your reading comprehension is poor. Work on it.

I didn't state that the overhaul requirement for piston engines is five years. I specifically stated that it is not. This is where your reading comprehension needs some work. With a little effort, you can do it.

Most all powerplants have calendar limitations requiring overhaul when operated under Part 135. The interval, as I correctly stated before, varies...but most assuredly the limits are there, and for good reason.
 

brokeflyer

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avbug just gets a little too excited when he gets to answer somone's question.

dont take it personal, he can't help it.
 

surveypilot

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It is very common to have to overhaul props on calendar long before the hour limit it up, but I can't say that I have ever hit the calendar limit on a piston engine. If you do, you probably have bigger problems than overhaul times, because you are not producing enough revenue to stay in business.
 
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