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Bravo oil consumption m20m -??? Bravo 1998


pkofman

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12 hours ago, alextstone said:

My usage also is one quart per 8 hours when the engine is healthy. Recently, that quickly went up to one quart every 3 hours and this sudden change was my early warning sign of a cylinder suffering from blow by of the rings and impending exhaust valve failure.

BTW, Lycoming provides a formula for "normal" maximum oil consumption:

"Lycoming uses the following formula to determine maximum oil consumption: (. 006 x BHP x 4 )/ 7.4 = maximum quart/hour consumption. This means that...."

For the Bravo: (. 006 x 270 x 4 )/ 7.4 = .087 qaurt/hour consumption maximum!!!

I think the biggest takeaway is to know your engine and watch for trends.

Also, I'm going to go out on a limb here and say that Mike Busch's messaging has really more to do with condition based maintenance (for part 91 ops) rather than hours, time in service or arbitrary "swapology" of parts such as a full top overhaul just because one or two cylinders are in need of replacement.

Alex

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Sorry for the confusion I created here....I am at home recovering from surgery (bored and medicated)and I had no business doing math problems online. I’m not going to correct the post though because it’s been addressed in detail and the correction might just serve to muddy the waters further.  

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1 hour ago, alextstone said:

I’m not going to correct the post though because it’s been addressed in detail and the correction might just serve to muddy the waters further.

If I may - perhaps editing the post and adding a comment about the issue would help some people that won't bother reading the whole thread? Just a thought! Get better!

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  • 3 months later...
18 minutes ago, affricate said:

I'm burning 1 quart every 3 to 4 hours. All compressions are good, and I'm 40 over TBO.


welcome out into the open...

Any idea where the oil is going to?

If it is one cylinder, or the turbo, or a single point that can R&R’d that would be great...

Best regards,

-a-

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1 hour ago, affricate said:

Yeah, doing a MOH soon. In the meantime, changing the oil / oil analysis every 25 hrs

It’s going to be a brand new plane!

If you haven’t already...

read up on exhaust system issues related to aging (hours on the parts) exhaust systems for TC’d engines...

Be on the look out for things like thinning tube walls, exhaust leaks, and be familiar with re-use of v-bands...

All typical safety issues of TC’d engines as they get used...

That short distance between the exhaust valves and the turbine... is a hellish environment... high pressure, high temp... continuous...

PP thoughts only, not a mechanic...

Best regards,

-a-

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If you're doing a lot takeoffs 5 hours/quart would not be too abnormal in my experience. When I'm flying 4-5 hours legs I go around 10 hrs between quarts and 6 hrs when I'm doing short flights around Florida.
Same here. Flew 15 hours last week and used 1.5 qts.

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