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  #11  
Old 12-24-2019, 12:30 AM
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rv8ch rv8ch is offline
 
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Default Ground break-in

This topic is a bit confusing to me. Everyone seems to agree that it's important to break-in the engine correctly, since if you get it wrong you are looking at 100s if not 1000s of extra cost to re-hone and try it again.

The engine builders have the engine in a test cell and already do a short run of the engine before shipping it to you - why wouldn't they do the full break-in? They already have it in ideal conditions to finish the job.

Besides a bit of hassle building a duct (someone will build a kit and sell it to us I'm sure), some boring time on the ground running the engine, having a spotter to keep people away from the prop, some extra noise at the airport, it does seem to me that doing the break-in on the ground would eliminate one source of distraction during the first few flights, and increase the likelihood of a successful break-in.

Could very well be that I'm over-thinking this - I've been known to do that - and after it's all said and done I'll switch over to the "just fly it" camp.
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  #12  
Old 12-24-2019, 01:14 AM
scsmith scsmith is offline
 
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Quote:
Originally Posted by Canadian_JOY View Post
There's a big terminology gap here that we have to bridge.

1) Run In - this is what Lycoming does at the factory. So many minutes and such-and-such RPM, then so many more minutes at another RPM. That's RUN IN. Done for you at the factory or any half decent engine builder.

2) Break-In - this is what you are doing on the airplane (unless you have done the overhaul yourself). This is where you are running the engine hard at high power setting to seat the rings.

I can't think of any good reason other than the altitude consideration for a ground-based break-in. The engine will be getting great big gulps of cooling air when you do break-in in flight. Boring holes over the airport at 75%+ power setting isn't all that tough to do. You'll be getting to know your airplane, and your engine. Then if you're lucky you'll see that "aha" moment when the temperatures start to settle and you'd swear you can feel the engine running more smoothly.

Unless you have troubles getting the engine to produce full power, thanks to density altitude concerns, flying it seems the most reliable method of breaking in.

Oh, just thought of another reason you might want to break it in on the ground... If you're located at an airport where you can't be reasonably assured of short ground run times before takeoff and after landing then you might want to do the first few hours under a cooling hood.
My engine came from the builder (Okanagan) already broken in. I'm not sure they intended that the "run -in" would serve as "break-in", but from the very first flights, my temps were normal, oil consumption low. Nothing changed over several hours. I concluded that it had already broken in during run-in. 600 hrs later, oil consumption is still 1 qt in 12 hrs.
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  #13  
Old 12-24-2019, 03:35 AM
svyolo svyolo is offline
 
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Had I know it was an option to have the rebuilder break in the engine, I would have done it.

I can think of numerous absolutely wonderful reasons to break your engine in on the ground. I can also think of a few risks, noise being the biggest one.

For me, breaking the engine in on the ground de-risks the first actual flight. I am doing it. And I will do it on the next build as well.
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  #14  
Old 12-24-2019, 07:17 AM
RV7ForMe RV7ForMe is offline
 
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Default I know it is rare but it does happen...

I also think it would be great to know that the engine runs for a few hours on the air frame before risking a first flight.

My buddy with his RV7A and stock IO360M1B with C/S flew for about 18 min before the darn thing quit...

Nobody was hurt and bend metal & broken plexiglas was fixed. A year later he tried again but had the rebuild engine run 8h on the test stand at the engine shop at perfect temperatures. Safe to say she was already broken in at first flight. 75h and counting. Beautiful flying machine! But I do see the appeal to trying things on the ground.
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  #15  
Old 12-24-2019, 01:15 PM
krw5927 krw5927 is offline
 
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Quote:
Originally Posted by RV7ForMe View Post
I also think it would be great to know that the engine runs for a few hours on the air frame before risking a first flight.

My buddy with his RV7A and stock IO360M1B with C/S flew for about 18 min before the darn thing quit...

Nobody was hurt and bend metal & broken plexiglas was fixed. A year later he tried again but had the rebuild engine run 8h on the test stand at the engine shop at perfect temperatures. Safe to say she was already broken in at first flight. 75h and counting. Beautiful flying machine! But I do see the appeal to trying things on the ground.
What was the cause of the engine stoppage in flight?
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  #16  
Old 12-24-2019, 01:41 PM
RV7ForMe RV7ForMe is offline
 
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Quote:
Originally Posted by krw5927 View Post
What was the cause of the engine stoppage in flight?
Kurt, nobody was able to determine that. Wasn't a great feeling trying for a second first flight without knowing what went wrong in the first but I think he is out of the woods now with 75h.
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  #17  
Old 12-25-2019, 09:13 AM
Canadian_JOY Canadian_JOY is offline
 
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I asked a local engine shop what they would charge to do the first 4 hours of break-in on an O-360. Their answer was a flat thousand bucks. I would certainly consider doing that if I once again were faced with the combination of new airplane, new engine and new prop.

In the case of our current O-360, before first flight it had several full-power ground runs to its credit, thanks to factory settings of prop and governor that were way off what they should have been (initial ground run produced 2300RPM, a far cry from 2700!). Those runs were all done using Mahlon Russell's terrific guidance for ground runs - limiting CHT to 300F, and not starting the engine again until one could comfortably rest one's hand on the cylinder while holding a conversation.

With good confidence the engine would make full power, the first two flights were very good flights, with the engine temperatures settling in at about 100 minutes of flying time. It ran noticeably better - it just felt better all around.
Hard to describe, but once you feel it, you'll know it. Total oil consumed during break-in was less than a half quart. The engine now consumes a quart in about 23 hours with about 200 flight hours in the logbook.
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  #18  
Old 12-30-2019, 10:37 PM
ivana ivana is offline
 
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Location: St. Helens, OR
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Default Thanks for all the info

Thanks for all the help guys. I found all i need to know and am going to do this. As to why, it's just a personal decision. New airplane, new engine, but old stock. It's just more than I want do deal with at one time. It's a Van's engine that I bought from a guy that sold his project and it's been in a box for several years. I'm pretty confident it's still ok, But this is how I want to do it. Thanks again for all the input.
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