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On the way back from Page Fly Inn, we had a sudden power loss during the hard climb.

After arriving KIGQ, we took the cowlings off and we saw green fluids on the carb trays.

We are wondering what caused the sudden power loss...

 

Attached video with sound you can hear loss of power at 5 sec ~ 6 sec mark.

Also, 4 pictures of carb trays and pipes into carbs are wet and green fluids are on the trays.

 

I called around to see what could have caused this...but it was a very scary moment and the last leg of our flight

 

ROTAX 912 POWER LOSS IN CLIMB.wmv

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Looks like coolant, but not sure why that would be in your drip trays...was there residue all over, or just in the trays?  What type of coolant are you using?  What did your temperatures do during the power loss?

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Have you looked IN the float bowls yet?

 

Our carbs are extremely vulnerable to the tiniest bit of debris - it can swirl up and block the main jet, and then either get ingested to no ill effect or managed to dislodge and settle back to the bottom of the bowl, waiting for the next inopportune moment to get sucked up again.

 

Condensed water can also collect there, causing a momentary hesitation as it gets ingested.

 

I think the coolant residue, if that's what it is, is an unrelated issue.

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The two coolants recommended by rotax for the USA are organic acid coolants (Dex Cool) and Evans waterless coolant.

 

Are you using evans coolant?

 

Anyways, as for the rest, you need to have someone take the carbs apart and investigate.

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I think the fluid is a mixture of old car gas stains and recent 100LL fuel. You likely had some fuel getting past the float needle which flooded the carb causing an extreme rich mixture for that side. It could be debris or a sunken float.

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Looks like coolant, but not sure why that would be in your drip trays...was there residue all over, or just in the trays? What type of coolant are you using? What did your temperatures do during the power loss?

If fuel comes in contact with the inside of the cowl, the carbon fiber will discolor it, resulting in a greenish tint.

 

What did the residue smell like?

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It happened at KGBG and outside temp was between 45-48, humidity 68% and around 3000~3500fts

No other symptoms after that 1~1.5 sec and I did try large throttle movements close to home base.

 

MrMorden - I tried to enhance the video to see temps, but was not successful...

I don't think any temps were affected though since we did not see any changes after that...

 

Anticept - We use Prestone Dex cool 50/50...i believe. (i will check when I get to the hangar tonight)

 

Tom - Rich mixture and or debris, would it cause us to be grounded?  We are planning to take our CT to Jim Leon @ ultralight place tomorrow.

 

WmIce - We didn't smell the fluid...

 

Hope this is not a huge problem which we have to constantly monitor while we are flying... :unsure:

We will it to Jim Leon @ ultralight place tomorrow morning...but, want to be sure if that is a good idea or not...?

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While you are checking the coolant, look at the color of the coolant. If it is changing colors, it is time to flush and put new stuff in. Anyways I had asked because of the green looking coolant is all.

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My DexCool looks like cherry cool-aid, I don't think that's coolant in the photos.

 

I think you have a fuel issue, either you sunk a float or had carb ice.  What was the dew point spread? 

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That's absolutely fuel, no question. I have seen this dozens of times. I always keep 6-10 carb bowl gaskets on hand.

Replace the carb bowl gaskets. Double check the carb floats for sinking and put a wrench on the fuel connection that goes into the carb.

 

 

First choice says gasket, but since the carb stumbled it is possible to be a sunk float and flooding on one of the carbs. That you'll have to check.

There is a video  on the forum that will show you how to push the carb back and lift it up to pop the bowls off or just call me.

 

The one time stumble may not be associated with the fuel drip. It could have just been a little debris. This can be checked when you pop the carb bowl off.

 

This bowl leak started on your way home. Your drip trays were dry and clean at the fly-in. I checked.

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If fuel comes in contact with the inside of the cowl, the carbon fiber will discolor it, resulting in a greenish tint.

What did the residue smell like?

  

 

Yes you are right, it smelled like fuel, I just checked the residue

 

 

My DexCool looks like cherry cool-aid, I don't think that's coolant in the photos.

I think you have a fuel issue, either you sunk a float or had carb ice.  What was the dew point spread?

 

Yes, also you are right, my coolant is not DexCool, it's something else...

 

 

 

That's absolutely fuel, no question. I have seen this dozens of times. I always keep 6-10 carb bowl gaskets on hand.

Replace the carb bowl gaskets. Double check the carb floats for sinking and put a wrench on the fuel connection that goes into the carb.

 

 

First choice says gasket, but since the carb stumbled it is possible to be a sunk float and flooding on one of the carbs.

That you'll have to check.

There is a video  on the forum that will show you how to push the carb back and lift it up to pop the bowls off or just call me.

The one time stumble may not be associated with the fuel drip. It could have just been a little debris. This can be checked when you pop the carb bowl off.

This bowl leak started on your way home. Your drip trays were dry and clean at the fly-in. I checked.

 

Thanks Roger! I will make sure to ask to check;

1. Gasket

2. Sunk float and flooding

3. Check both bowls for debris

 

Thanks guys for your help one again!

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My DexCool looks like cherry cool-aid, I don't think that's coolant in the photos.

 

I think you have a fuel issue, either you sunk a float or had carb ice.  What was the dew point spread? 

 

Evans coolant is green. That's why I had asked about the coolant type. Dex Cool turns to orange mud when it gets old and nasty.

 

 

  Yes, also you are right, my coolant is not DexCool, it's something else...

 

*If* it's evans, just remember to never add water to it, only fresh evans coolant. Evans will gel if it comes in contact with water. As a recommendation, find out what it is so you know.

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I had same sticky greenish residue in trays... Definitely remnants of lots of dried fuel. 'Went away after a carb cleanup and gasket replace. Occasional smell of fuel went away, too.

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So, we flew this morning to take our bird to Jim Leon @ ultralightplace.

We found a few things which we did not know until he mentioned about them and confirmed by Tom.

 

1. Our fuel line on the picture is not a standard Rotax fuel line (shown stainless steel)

a. Stainless steel fuel lines are standard on CT up to 2006 and changed to rubber

2. Greenish color fluid is fuel (thanks everyone for help)

a. Jim agreed that if we used 100LL, then fuel could have turned greenish color

3. Stainless steel fitting was leaking fuel...a lot...may have caused the issue, but might also be debris.

 

Jim told us stainless steel tubes can be brittle and no other Rotax engines he saw has stainless steel tubes.

Then, he saw that connection was leaking fuel and might have loosened over time via vibrations or simply worn out...

 

Therefore, we made a call to change the fuel line from stainless to teflon tubes...despite he said "you really don't have to change".

Also, he did not see carburetors been rebuilt or not, so again we decided to rebuild carbs despite he said "you don't have to do that".

But, our thinking right now is to get them done now so we don't want to worry about them while we are flying.

 

So, Jim took us to his "clean room" to tear down carburetors side by side and he instructed me to tear down one right next him while he is also doing one. He said both carbs are pretty dirty in his opinion and it was a good decision that we decided to do the rebuild. Then, also he mentioned that floats on one side of the carb was too high...he said he need to readjust the needle (he pointed out close to the needle area)

 

The problem we felt during the flight might not be related to neither as you all pointed out, but I believe process of elimination is a good thing.

If the power loss did not come from fuel line leaks & carburetors, then at least we can focus on something else.

 

Jim also said, if the power loss is FOD, then no need to drain the fuel and engine will get is through just like it did then.

But, all in all, I think we made the right decision to take care of them now and I hope either dirty carbs or fuel leak was the issue.

 

fuel line shown is stainless steel

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Rotax recommends changing to rubber if problems come up with the steel that can't be fixed easily. Stainless steel lines are plain brazed lines in CT configuration, and are much more prone to damage, especially by poorly trained mechanics. Whatever you do, never bend the lines out of the way to work on something, the entire assembly must be removed to prevent work hardening and stress on the lines. The thing that causes failures of the lines are when they are bent back less than perfect, and side loads and vibration weaken the lines. EDIT: Teflon lines per roger*

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Those stainless lines should work fine and I have never heard of one failing. Could someone damage them, well certainly. The new red fuel lines from Rotax are not rubber, but Teflon. Cost is approximately $360. Teflon fuel or oil lines aren't cheap. The change from stainless to Teflon was optional and many people still use them. Unless the fuel line was compromised then just tightening the fitting would have sufficed. 

My guess is the float level being too high (causing flooding of the carb, leaking and or rough running), a gasket needing to be replaced or a loose fitting caused the fuel leak.  Your fuel system has 4 filters before the carb , so if there is something in the carb look at the last fuel hose that comes off the bottom of the fuel pump. Debris could also have caused a temporary rpm loss and a small piece of debris could move through the carb depending on its size. It could also just blocked the main jet and moving around in the air and changing throttle position may have made it move away from the main jet.

 

The only way to rule out any of these items above is to just do what you're doing and check the entire system. The carb rebuild was optional.

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I would think stainless fuel lines would be preferable to a synthetic like teflon, but that's just me.  When I was building my Sonex I was planning to use all flexible braided stainless lines in my airplane, like the ones used in race cars.  Not sure what those are lined with though, could very well be teflon.

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The stainless line was standard Rotax, but from earlier years. I think the switch was in 2007. I did have an airplane that had a leak in the area of the line at the carb. It wasn't the line, but the fitting in the carb that it screws to the was leaking. A new gasket ring and sealer on the threads took care of the leak. While the new Teflon line is about $360, you will also need 2 banjo bolts, 2 spacers, and 6 950-141 gasket rings. It was my understanding from class that the switch to Teflon was because some of the stainless lines were starting to crack.

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Teflon hoses are on condition, per an SB that came out earlier this year.

 

The downside to teflon is that it tends to harden over time. It's not a good hose choice if there is a lot of flexing going on, because it will set, and if you try and bend it, you will crack it. The hardening isn't compromising the hose itself, it's just a natural thing that teflon does.

 

Stainless steel will last a LONG time, as long as it is properly cared for. Proper care means it should not be excessively flexing, or having side pressure on the fittings. That's why I said, if it starts having problems that can't easily be fixed, switch to teflon. Otherwise leave well enough alone!

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Those stainless lines should work fine and I have never heard of one failing. Could someone damage them, well certainly. The new red fuel lines from Rotax are not rubber, but Teflon. Cost is approximately $360. Teflon fuel or oil lines aren't cheap. The change from stainless to Teflon was optional and many people still use them. Unless the fuel line was compromised then just tightening the fitting would have sufficed. 

My guess is the float level being too high (causing flooding of the carb, leaking and or rough running), a gasket needing to be replaced or a loose fitting caused the fuel leak.  Your fuel system has 4 filters before the carb , so if there is something in the carb look at the last fuel hose that comes off the bottom of the fuel pump. Debris could also have caused a temporary rpm loss and a small piece of debris could move through the carb depending on its size. It could also just blocked the main jet and moving around in the air and changing throttle position may have made it move away from the main jet.

The only way to rule out any of these items above is to just do what you're doing and check the entire system. The carb rebuild was optional.

Thanks Roger! Your blessing do give us peace of mind. Just so you will not boot me out of this forum, I just changed "rubber" to "Teflon" to be sure untrained people like me will not make a mistake...also, I don't want Jim to think I am untrainable...

I will also ask Jim to check hose cling out of the fuel pump! Thanks again!

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Teflon hoses are on condition, per an SB that came out earlier this year.

The downside to teflon is that it tends to harden over time. It's not a good hose choice if there is a lot of flexing going on, because it will set, and if you try and bend it, you will crack it. The hardening isn't compromising the hose itself, it's just a natural thing that teflon does.

Stainless steel will last a LONG time, as long as it is properly cared for. Proper care means it should not be excessively flexing, or having side pressure on the fittings. That's why I said, if it starts having problems that can't easily be fixed, switch to teflon. Otherwise leave well enough alone!

Thanks, I understood that stainless will last LONG time and is better choice for this application. But, the main reason is that unfamiliarity of its existence made me to choose Teflon. I understand that Jim has been servicing Rotax since 96 (first LSA service station licensed by FAA) and even he rebuild engines for LEAF. Also, every LSA owners knows him as the Guru of Rotax here in Chicago, therefore I trust him like I trust Roger and Tom. I think owners some times need to change things for the mechanics, so make it easier or familiar for mechanic to work on your aircraft is necessary. For those who know how to service your own aircraft is a different story though...

 

By the way, as Roger mentioned, I will do the process of elimination and I will ask Jim to check "the last fuel hose that comes off the bottom of fuel pump".

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I still have the stainless steel fuel connector on a CTSW 2006.   Have not had any problems with this until today.  I recently completed a rubber hose change and a couple of flight hours after the change, the connector started leaking in flight.    Luckily no power loss, no vibration and the engine performed perfectly for the 1 hour flight except that my passenger and I noticed a very faint smell of fuel that got us a little concerned.    Upon landing I had a noticeable fuel leak with fuel dripping from under the cowl.   (I estimate 4 to 5 drips/ second).    Initial findings;   the connector was loose, and required some tightening. After some tightening there was still a small drip and we had to redo the attachment making sure the connector was aligned, seated properly and tightened.  Ground run ups seems  be good now but I will be checking on this much more.   

Are the older CTSW's still using the stainless steel connectors or have most of you splurged and moved to the Teflon hoses?      Seems the complete Teflon fuel hose change would run $2k ?

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