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#31
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"Michael" wrote: TBO's are usually about 2000 hours, but I don't actually know anyone with more than 2000 hours of piston GA experience who has not had an engine failure. Pardon me, Michael, but there's something puzzling about this statement, to me. (I know only one pilot with over 2000 hours (~8,000), and he's never had an engine failure, but that's not what puzzles me). I know three airplanes that have gone to 2000-hr. TBO two or three times without an engine failure. Mine went 4500 hours without one before I bought it. Isn't that equivalent to four pilots' going 2000+ hours each without an engine failure? How do you account for the unsettling experiences of your acquaintences? -- Dan C172RG at BFM |
#32
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"Dan Luke" wrote
Pardon me, Michael, but there's something puzzling about this statement, to me. (I know only one pilot with over 2000 hours (~8,000), and he's never had an engine failure, but that's not what puzzles me). I know three airplanes that have gone to 2000-hr. TBO two or three times without an engine failure. Mine went 4500 hours without one before I bought it. Isn't that equivalent to four pilots' going 2000+ hours each without an engine failure? How do you account for the unsettling experiences of your acquaintences? Don't know. Were these perhaps small, 4-cylinder, carbureted, normally aspirated low compression engines? In my experience, most engine failures seem to occur on engines that are large, 6+ cylinder, injected, turbocharged, high compression, or some combination. I only know one person who had a failure with a Cont O-200, one with a Lyc O-320, and none with a Lyc O-360. All engines are clearly not created equal. I think there's some self-selection going on - most pilots who stay in GA past 1000 hours (except those who spend all their time in the right seat of a primary trainer) tend to move into higher performance airplanes where the engines are less reliable. I believe something like 10% of piston engined Malibus have experienced inflight engine failures. I would also guess that the rate of failure in C-150's is at least an order of magnitude lower. Michael |
#33
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did you find out the reason for your engine failure yet ?
"O. Sami Saydjari" wrote: Greg Copeland wrote: On Mon, 19 Apr 2004 13:53:36 -0600, Newps wrote: "Greg Copeland" wrote in message news Well, I guess that puts us back to the original question. I, like the orginal article's author, thought historical statistics were used to establish TBO numbers. If no one is tracking this information, where do the TBO numbers come from? Insurance liability statistics from wrecks? TBO comes from two places. 1) Marketing 2) A Guess LOL! Is anyone else bothered by this? I guess it's not really saying MTBF, it's just saying, your engine is ganna be tired when it hit this number. So, I guess that really isn't all that bad after all. I, for one, prefer to base my decisions on facts instead of speculations. How do they know the engine will be tired after x hours? What does tired mean? The only thing that would be meaningful to owners is probability of failure at X hours. It does not seem that collecting the data and calculating MTBF would be that hard. I sure hope the engineers who designed the engine did not use the same attitude with respect to the components they used! "Crankshaft A is 20% cheaper than Crankshaft B? Well, who cares, everyone knows that everyone just makes the reliability numbers up anyway. Let's use Crankshaft A." Arg! |
#34
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Everyone I have talked to who has this engine in their turbo arrows always
say to not fly over 65% power, if so you will not make it to TBO, the exception is those that have an intercooler installed. I only fly mine at 65% power, so far no problems in the year I have had it. Aaron Coolidge wrote: O. Sami Saydjari wrote: : OK. I have gone back through my logs and compiled the following : information on my aircraft. snip I think you may find that the TSIO360 engine is considered one of the least reliable engines out there. This is what's keeping my from buying a Mooney 231. I did some research into the "Service Difficulty" reports that the FAA tracks, in concert with A&P mechanics, and it seems like the engines just devour cylinders. The SDR info is available on the web. From reading many ads for 231 airplanes I have seen most engines have a top overhaul at 800 or so hours, and a major overhaul at 1600 or so hours. -- Aaron Coolidge (N9376J) |
#35
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Not yet. Awaiting word from oerhaul shop. I will report back as soon
as I know anything. -sami Jeff wrote: did you find out the reason for your engine failure yet ? "O. Sami Saydjari" wrote: Greg Copeland wrote: On Mon, 19 Apr 2004 13:53:36 -0600, Newps wrote: "Greg Copeland" wrote in message news Well, I guess that puts us back to the original question. I, like the orginal article's author, thought historical statistics were used to establish TBO numbers. If no one is tracking this information, where do the TBO numbers come from? Insurance liability statistics from wrecks? TBO comes from two places. 1) Marketing 2) A Guess LOL! Is anyone else bothered by this? I guess it's not really saying MTBF, it's just saying, your engine is ganna be tired when it hit this number. So, I guess that really isn't all that bad after all. I, for one, prefer to base my decisions on facts instead of speculations. How do they know the engine will be tired after x hours? What does tired mean? The only thing that would be meaningful to owners is probability of failure at X hours. It does not seem that collecting the data and calculating MTBF would be that hard. I sure hope the engineers who designed the engine did not use the same attitude with respect to the components they used! "Crankshaft A is 20% cheaper than Crankshaft B? Well, who cares, everyone knows that everyone just makes the reliability numbers up anyway. Let's use Crankshaft A." Arg! |
#36
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Jeff, I have been flying mine at 65% power....and I have an
intercooler. -sami Jeff wrote: Everyone I have talked to who has this engine in their turbo arrows always say to not fly over 65% power, if so you will not make it to TBO, the exception is those that have an intercooler installed. I only fly mine at 65% power, so far no problems in the year I have had it. Aaron Coolidge wrote: O. Sami Saydjari wrote: : OK. I have gone back through my logs and compiled the following : information on my aircraft. snip I think you may find that the TSIO360 engine is considered one of the least reliable engines out there. This is what's keeping my from buying a Mooney 231. I did some research into the "Service Difficulty" reports that the FAA tracks, in concert with A&P mechanics, and it seems like the engines just devour cylinders. The SDR info is available on the web. From reading many ads for 231 airplanes I have seen most engines have a top overhaul at 800 or so hours, and a major overhaul at 1600 or so hours. -- Aaron Coolidge (N9376J) |
#37
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Jeff wrote in
: Everyone I have talked to who has this engine in their turbo arrows always say to not fly over 65% power, if so you will not make it to TBO, the exception is those that have an intercooler installed. I only fly mine at 65% power, so far no problems in the year I have had it. I don't think it is so much a matter of what power as what temperature. Reducing power helps with the temps, of course, so... Watching the JPI EDM float around under various conditions, it's easy to see how the cylinder temps can get out of hand, even at 65% power. The engine is somewhat tightly cowled, no cowl flaps, and comes (originally) with a fixed wastegate. The Merlyn helps a lot on that, especially here in Texas (where takeoffs are from almost sealevel and ambient temps may well be over 100F -- fun to notice your oil temp already reading before you start the engine). I like to keep my CHT's below 400 or so, even in climb (and more like 330 for cruise). But only a few times, usually a LONG climb at gross, have I needed to cruise climb for temperatures (I may do so anyway, but that's just for efficiency). I don't have an intercooler, and don't have any problem at 75% power, or even higher (when LOP) during cruise. Interstingly enough, the highest EGT readings will be at lower power, down around 55%, where 1550+ may be common (CHT's will be low). And during a climb sometime, try this experiment - try both 65% or 75% power, vs. full power. I'll bet you will find that climbing at 41" is a LOT cooler (both CHT and EGT) than climbing at cruise power. ----------------------------------------------- James M. Knox TriSoft ph 512-385-0316 1109-A Shady Lane fax 512-366-4331 Austin, Tx 78721 ----------------------------------------------- |
#38
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"O. Sami Saydjari" wrote in message ...
I talked to TCM today to register that I am the new owner of one of their engines. Just in passing, I mentioned that their engine failed recently within a few hundred hours after major overhaul. They seemed completely uninterested in knowing this fact. I asked if they kept actual statistics on actual dependability of their engines. She said that they did not, to the best of her knowledge. That seems quite odd. Where do they get TBO numbers from. I always assumed there was some serious historical statistical date to back these up. Does anyone keep these statistics? Perhaps A&Ps report such failures? Overhaul shops maybe? I sure hope someone is tracking the information. -Sami N2057M, Piper Turbo Arrow III I supect that in the past there were manufacturers who did studies to convince the FAA that their engines could be expected to go 2000 vs their competitors 1200 or 1500, and used this as a selling point. Now noone has any interest in changing it. -- Gene Seibel Hangar 131 - http://pad39a.com/gene/plane.html Because I fly, I envy no one. |
#39
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James M. Knox wrote:
: I don't have an intercooler, and don't have any problem at 75% power, or : even higher (when LOP) during cruise. Interstingly enough, the highest : EGT readings will be at lower power, down around 55%, where 1550+ may be : common (CHT's will be low). And during a climb sometime, try this : experiment - try both 65% or 75% power, vs. full power. I'll bet you : will find that climbing at 41" is a LOT cooler (both CHT and EGT) than : climbing at cruise power. James, this agrees with what the Mooney people say. They recommend 2700/41" (or whatever full power is, if you've got an intercooler) for climb, using airspeed and cowl flaps to adjust engine temps. The theory being that you will be in the climb for a lot less time, I presume. When you say 41" is a lot cooler, are you increasing airspeed or maintaing the same airspeed as in a 75% or 65% climb? -- Aaron Coolidge (N9376J) |
#40
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yes I know, you have all the goodies that are suppose to extend the life of your
engine. "O. Sami Saydjari" wrote: Jeff, I have been flying mine at 65% power....and I have an intercooler. -sami Jeff wrote: Everyone I have talked to who has this engine in their turbo arrows always say to not fly over 65% power, if so you will not make it to TBO, the exception is those that have an intercooler installed. I only fly mine at 65% power, so far no problems in the year I have had it. Aaron Coolidge wrote: O. Sami Saydjari wrote: : OK. I have gone back through my logs and compiled the following : information on my aircraft. snip I think you may find that the TSIO360 engine is considered one of the least reliable engines out there. This is what's keeping my from buying a Mooney 231. I did some research into the "Service Difficulty" reports that the FAA tracks, in concert with A&P mechanics, and it seems like the engines just devour cylinders. The SDR info is available on the web. From reading many ads for 231 airplanes I have seen most engines have a top overhaul at 800 or so hours, and a major overhaul at 1600 or so hours. -- Aaron Coolidge (N9376J) |
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