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TOPIC: Manifold Fluctuation

Manifold Fluctuation 2 months 3 weeks ago #676

  • STEVE ELLS
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Before you start pumping contact cleaner through those components, please call Main Turbo, a widely recognized turbo charger repair facility to see if the chemicals in contact cleaner will damage any of the interior parts of these components. The phone is 888 847-8008. Website is www.mainturbo.com
My recommendation is to use what's called Stoddard solvent; it's a petroleum based cleaner. It's also known as mineral spirits.
I've never heard of anyone using contact cleaner for this task.
Please report back with what they say.
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Manifold Fluctuation 2 months 3 weeks ago #675

I'll try different RPMs next time I'm that high to see if that cleans it up any. I also had some recommendations and instructions from an A&P to use contact cleaner to backflush the wastegate, regulator and hoses that typically get built up on the T206Hs.
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Manifold Fluctuation 2 months 4 weeks ago #673

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Hi Sorry it's taken a while to respond.
Are you familiar with the term "bootstrapping?" Bootstrapping is when there's only enough exhaust gas pressures passing by the turbine wheel in the Turbocharger to provide a neutral (not positive) pressure at the engine intake. I mention this because the erratic MAP begins it starts when you start your climb to a higher cruise altitude and stops when you descend.
When the turbocharge system is bootstrapping any small change in altitude (air density) or aircraft attitude (variances in inlet air pressure) will affect the MAP in a linear fashion.
It's pretty easy to see that the cure for bootstrapping is to increase the engine RPM, thereby increasing exhaust pressures which results in a positive inlet air pressure.
If you took closely at the relationship between RPM and MAP, especially at about 1:20 into the flight you'll see how RPM affects both fuel flow and MAP. In fact, this relationship is evident all through the charts you've provided.
Mouse Milk is the best stuff for lubing the wastegate so you did the right thing there.
I suggest that whenever you experience erratic MAP, especially at higher altitudes that you bump the RPM up; I think you'll find your erratic MAP problem goes away.
Happy Flying
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Manifold Fluctuation 3 months 1 week ago #671

I've recently purchased a 2008 T206H and have been having issues with manifold fluctuations at altitude. In the last flight (today) it started fluctuating at 16,500. I'd keep the throttle, mixture and prop as reasonably stable once at 17,500. I've also experienced issues at lower altitudes (14,500) on other flights.

I did use some Mouse Milk on the wastegate shaft the best I could do it without disassembling anything and moving the wastegate with an adjustable crescent wrench. At this point I was going to bring it into the shop, but I'd like to consider opinions on the culprits. 1. Wastegate, 2. Pressure Regulator, 3. Fuel Pump (I forgot to turn on the electric fuel pump to see if that helps). The engine does have 1700 hours, so it's not unlikely something is worn out.

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