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John Vance

Power loss in flight

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15 minutes ago, John Vance said:

Yes, it was cloudy and there had been some light showers around a couple of hours prior.  I didn't encounter any. 

Okay.

OAT of 53°f and high humidity are ideal conditions for carb icing in a CT. It is rare, but does happen.

 

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36 minutes ago, WmInce said:

Okay.

OAT of 53°f and high humidity are ideal conditions for carb icing in a CT. It is rare, but does happen.

 

I'm curious about carb heat performance in the LS.  I generally don't worry about carb ice in the CT, and don't apply carb heat for landings.  I suppose it's possible that it did ice up when I cut the throttle for landing.  How long does it take for carb heat to work in this airplane?

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My experience with carb icing occurred in similar temps as yours John.  I was at altitude and dodging snow clouds with throttle at low cruise rpm.  Noticing rpm's dropping, I added carb heat and kept the throttle "as is".  The rpm's came back up within 1.5 to 2 minutes.  If you might have been running at low engine speed the engine compartment ambient may not have been sufficient for the marginal carb heating system to melt carb ice?  This is one possibility.  The other is you may (or may not) see some debris when you drop the bowls.  I say "may not" because of the possibility that a fleck of oxidation or dirt might have ended up going thru the carb.

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Thanks, Dick. I hope to spend a little time in the hangar today, sorting this out. Also thanks to everyone else who contributed!  

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And the winner is............Gunk in the Carburetor Bowl!  

Three different kinds, actually. I'll start another thread on this - I'm hoping for a teachable moment for someone else, and a learnable one for me.  Now that the bowls are clean, the engine runs great with no hint of roughness at any RPM. 

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On 3/22/2018 at 4:52 AM, John Vance said:

Could you describe how your engine was behaving?  Was it intermittent or consistent?  Did problems occur just after refueling, or ??

Yes. It happened after I filled up on 91 octane no ethanol gas. I had a normal run up. Full power take off. RPMs dropped to 4000 at 100 feet agl. The last inch of throttle travel had no effect. At first I thought it was sticking throttle cables so I replaced them. It was bad gas. Its an easy thing to try. Just drain your tanks (use the gas in your car) and fill up on 100 LL. Like I said, it happened twice to me each year in April from the same gas station. My engine had about 700 hours on it at the time.

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25 minutes ago, bitten192 said:

Yes. It happened after I filled up on 91 octane no ethanol gas. I had a normal run up. Full power take off. RPMs dropped to 4000 at 100 feet agl. The last inch of throttle travel had no effect. At first I thought it was sticking throttle cables so I replaced them. It was bad gas. Its an easy thing to try. Just drain your tanks (use the gas in your car) and fill up on 100 LL. Like I said, it happened twice to me each year in April from the same gas station. My engine had about 700 hours on it at the time.

Thanks for your response. I think my problems were a little different, though. Just the day before, I had flown for 1.5 hours with no issues, and didn't add any fuel before the problem flight. I will keep the seasonal gas changes in mind. 

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Reminder - Clean those carb bowls.   I was doing a runup and had the engine stumble.  From 4000 rpm, lost  roughly 100- 200 rpm and was 'grumbling' bad.   This was whilst i was doing a 'mag check' so initially i thought it was a problem with my recently overhauled modules.   When i was switching to "1"  then "2"   then to  both i would sometimes getting a big drop and the engine roughness on "1"  and then when i would switch to both and go back to "1"  it was running fine again.    I repeated this many many times and sometimes rough and sometimes not.     Eventually i inspected the bowls to find all that dirt in there.   Argh.   After cleaning,  start up and 15 mins of  repeated "1" "2" "Both" mag check it didnt produce a big drop or engine roughness anymore.     I hope this was the final cause of the rough engine.  

74327177_575942186442540_4023268114830758967_n.jpg

105594419_879982152482196_6340364441781704525_n.jpg

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I don’t get it ... where all that crap is coming from ? 

I had power loss on take off once but that was caused by a chipped, tiny piece of the carb float ....

My carb bows are 8 years old (2012) and look pretty much brand new ... is this premature aging of carb bowls I see on other planes related to weather, fuel or what ?
 

 

A38B822D-41B1-4509-94CB-FE830F05B67C.jpeg

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Yup, you can see how badly my carb bowls are corroding.   Will have to check my logs but I think Ive had these for 7-8  years.  I did replace my first set after roughly 5 years as  those too had corrosion issues.  (2006 CTSW)  Im using 100 Unleaded no ethanol  (not 100LL Avgas).    Never had visible water in the fuel.   Note:   Your 8 year carb bowls look great !!

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Cdarza - nice video/pics. This illustrates the problem nicely. I’ve been checking the bowls every 3 months, and that seems to keep it under control. 

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That looks like ethanol gas that has been sitting for a while I have seen carbs. that

look like ash trays from that fuel sitting for long periods of time. I have been running

ethanol gas for years my bowls still look like new. I never let it sit long without  running

or flying it.

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5 hours ago, procharger said:

That looks like ethanol gas that has been sitting for a while I have seen carbs. that

look like ash trays from that fuel sitting for long periods of time. I have been running

ethanol gas for years my bowls still look like new. I never let it sit long without  running

or flying it.

This seems to be a hit or miss problem.  Cdarza has seen this with two bowl sets and hasn’t been using ethanol. Warmi’s look factory new after 8 years. Procharger uses ethanol but flies regularly and his are like new. Another guy I know uses ethanol, flies the crap out of his airplane, and has had a power loss event due to corrosion.  It’s happened to me but I’m managing it. My takeaway is - don’t take it for granted that your bowls are OK. Take a peek every once in awhile. 

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