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exceeding TBO on Continental 0200-A
Hello everyone. I'm continuing my quest to buy the best deal in America
today. Another option I've looked at is purchasing a low price Cessna with an engine that's past it's recommended time between major overhaul. Some of the sellers I've spoken with are insistent that recomended times aren't important, it's the condition of the engine that matters (ie. not making metal). I'd like some feedback from people who've purchased aircraft with high time engines. What should I expect, and what precautions can be taken to keep a high time engine flying (with the plane attached). thanks, m. |
#2
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Hello everyone. I'm continuing my quest to buy the best deal in America today. If you're talking about acquiring something that you are going to haul yourself and others up and away from the earth's surface, and move through the atmosphere and safely return yourself and others to earth, alive and well, I respectfully suggest reviewing your priorities. And what do you mean by "the best deal" anyway? How do you measure that? www.Rosspilot.com |
#3
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When the engine starts making metal, you've got an expensive overhaul on your
hands. Normally, you can get two, sometimes three, major overhauls/repairs (see another thread for which of these words you want to use) out of the bottom end before you have to undersize the crank. If you go until the engine makes metal, and depending on what metal it is, you may not even have a reusable crank when you pull it apart, and now you are really talking MONEY. Same for the jugs. If it is pistons that are making metal, then they are getting loose and sloppy in the bore and this accelerates wear tremendously. Exhaust valves are in the neighborhood of $200 apiece, and the guides are not far behind if you have to machine the guide bore. Wear is not linear. It is exponential, and the longer you go past RTBO, the further you are up on the exponential curve. Now, if you are REALLY looking to fly inexpensively, buy a relatively high time engine, put a couple of hundred hours on it, and then figure out which end of the wrench gets greasy. Find yourself a mechanic willing to do an "owner assisted" repair/overhaul. The O-200 is about as bonehead simple as you can get, and all the machine work is done by an outside facility. You get back straight/chromed cylinders with the valves installed and lapped, fitted pistons with fitted rings, case inspected, crank inspected, cam inspected/overhauled, and the like. You can send out the mags, carb, vacuumpump, and any of the other accessories you want. From there on it is tinkertoy simple (with expert advice) to put it back together. Roughly? Including R&R and labor to dis/assemble? Half. The HARD part is having the guts to pull it apart yourself. However, with a digital camera recording every step, putting it back together is a simple reversal of the process. Just my 8% of two bits, mindya. Jim -Another option I've looked at is purchasing a low price Cessna with an -engine that's past it's recommended time between major overhaul. Some of the -sellers I've spoken with are insistent that recomended times aren't -important, it's the condition of the engine that matters (ie. not making -metal). Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
#4
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Jim Weir wrote: The HARD part is having the guts to pull it apart yourself. I never had any problem taking things apart. It's trying to figure out where the leftover pieces were supposed to go after I get it back together that gives me problems. :-) George Patterson None of us is as dumb as all of us. |
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"Marty from Sunny Florida" wrote
Another option I've looked at is purchasing a low price Cessna with an engine that's past it's recommended time between major overhaul. Some of the sellers I've spoken with are insistent that recomended times aren't important, it's the condition of the engine that matters (ie. not making metal). That's somewhat but not completely true. Parts do wear. Having said that, if we're talking about an O-200 that is high in hours but low in calendar years (say 2000+ hours in less than 10 years) and is not making metal, not using excessive oil (anything over 1 qt in 5 hours would be considered excessive for that engine), and has good compressions - keep running it. I've seen those engines go for 3000+ hours. I've never seen one fail in flight due to causes that could in any way be related to running past TBO. Just realize that an engine won't run forever - you can exceed TBO, but not indefinitely. It WILL start making metal, using excessive oil, having low compressions, etc. I'd like some feedback from people who've purchased aircraft with high time engines. What should I expect, and what precautions can be taken to keep a high time engine flying (with the plane attached). I bought a plane with an O-320 with 2200 hours. I put another 150 on it the following year. Then overhauled because a bolt was cracked and the case had to be split to replace it anyway. Crank passed, cam passed, couple of gears were replaced. Nominal overhaul. Had the bolt not cracked, I likely would have gotten another 100-300 hours out of it. Michael |
#6
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As with anything, it all depends....
How many hours has it flown per year over the past 5 years. In those 5 years, what do the engine logs show? Any top overhauls, cylinder replacements, etc.? I bought a Cherokee 6-300 with about 1750 SMOH on it. The airframe, interior and panel were in 10+ condition, so I compromised on the engine time in favor of the rest. Logs were clean, and it had been flown a lot over the prior 5 years. Well, about 100 hrs and an annual insp. later, it's still a champ with good compression, low oil consump and no metal. I'm confident I'll at least make it to 2000. I had a Cherokee 140 that I bought with 1830 SMOH on it. It had a top overhaul at 1500, and fairly regular use over the previous years. I babied it and did 50 hr oil changes. It flew to 2200, and it was still doing well, but I had the budget and time so I had a Penn Yan exchange done for a 0 SMOH powerplant. If, on the other hand, the engine has had low usage(like 30-40 hrs/year) over the past 5, and/or maybe some work on the engine beyond the standard inspections and routine maintenance, you should think twice. The nice thing about getting a high time engine in good condition is that those last hours, whether they are 10 or 200, are essentially 'free' because you've already factored in the price of an overhaul(right??!) down the road. Once you accomplish that, the slate is wiped clean and the 'new' engine is all yours and you should have fewer worries percolating around in the back of your head because you know how it's been flown(once you break it in). |
#7
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"Marty from Sunny Florida" wrote in message ... Hello everyone. I'm continuing my quest to buy the best deal in America today. Another option I've looked at is purchasing a low price Cessna with an engine that's past it's recommended time between major overhaul. Some of the sellers I've spoken with are insistent that recomended times aren't important, it's the condition of the engine that matters (ie. not making metal). I'd like some feedback from people who've purchased aircraft with high time engines. What should I expect, and what precautions can be taken to keep a high time engine flying (with the plane attached). Just so you have the right perspective about TBO... The Savvy Aviator #4: Debunking TBO http://www.avweb.com/news/columns/187037-1.html |
#8
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**********Hello everyone. I'm continuing my quest to buy the best deal in
America today.************* Let'see. There are 106 C-150's in TAP right now. And to get a "good deal" you plan on buying a run out and continue to operate it? Sellers will LOVE you! Karl |
#9
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Jim Weir writes:
When the engine starts making metal, you've got an expensive overhaul on your hands. Normally, you can get two, sometimes three, major overhauls/repairs (see another thread for which of these words you want to use) out of the bottom end before you have to undersize the crank. Do they resurface aircraft cranks? When marine/truck/pricey auto cranks get worn undersize, they a Built back up to the right diameter. A welder goes back and forth across each bearing surface as the crank rotates; building up a solid surface. The crank is chucked into a "crankshaft lathe"... It's then spun slowly while a toolpost grinding wheel grinds each surface back to spec. ~Last step is to redrill the oil passages down the crank. Now, it's almost straightforward for the main bearings -- they are in line with the axis of the crank. But the *rod* bearings are a different story. What's done there is the chucks at both ends of the lathe have offsets - you shift them sidewise until the rod bearing in question *is* centered. (The two chucks are kept in exact sync by a driveshaft under the tool bed.) The whole deal looks like f*$(^9& magic when you see it in progress. The crank ends, mains and other throws are flailing around seemingly randomly...but that one rod bearing is dead bang centered.... (The lathe I saw had a ~16' yes sixteen foot marine crank in it.) -- A host is a host from coast to & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
#10
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On Fri, 11 Jun 2004 05:02:26 +0000 (UTC), David Lesher
wrote: Not only do (most?) engine manufacturers not allow the automotive process you describe (to "save" a crank), there are some that don't allow any grinding at all to go undersize on the journals. Truth be known, with the "average" light aircraft/engine, you can go 2 or 3+ overhauls (properly operated / maintained) without buggering up a crankshaft. P-51 owners tend to rebuild the bottom end (spare engines on hand) every so often precisely for that reason..... i.e., new/serviceable cranks are impossible to find and/or obscenely expensive, and in the long run, it's cheaper to re-bearing/rebuild the engine than it is to run it until it starts making metal. Bela P. Havasreti Jim Weir writes: When the engine starts making metal, you've got an expensive overhaul on your hands. Normally, you can get two, sometimes three, major overhauls/repairs (see another thread for which of these words you want to use) out of the bottom end before you have to undersize the crank. Do they resurface aircraft cranks? When marine/truck/pricey auto cranks get worn undersize, they a Built back up to the right diameter. A welder goes back and forth across each bearing surface as the crank rotates; building up a solid surface. The crank is chucked into a "crankshaft lathe"... It's then spun slowly while a toolpost grinding wheel grinds each surface back to spec. ~Last step is to redrill the oil passages down the crank. Now, it's almost straightforward for the main bearings -- they are in line with the axis of the crank. But the *rod* bearings are a different story. What's done there is the chucks at both ends of the lathe have offsets - you shift them sidewise until the rod bearing in question *is* centered. (The two chucks are kept in exact sync by a driveshaft under the tool bed.) The whole deal looks like f*$(^9& magic when you see it in progress. The crank ends, mains and other throws are flailing around seemingly randomly...but that one rod bearing is dead bang centered.... (The lathe I saw had a ~16' yes sixteen foot marine crank in it.) |
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