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I think my floats flunked.

cactusman

Well Known Member
So today was clean-up day. I had been getting that intermittent ACTV ADHRS VIB warning so I installed the new Vans rib in the back (what a pain - I highly recommend current builders do it while they can if it is not in the new kit), and I decided to check my floats to comply with the newly revised Rotax mandatory s/b....mainly because on my last flight I detected some fuel smell on decent, some erratic fuel PSI and FF readings, and a check showed some gas in left carb tray.

The carbs were balanced, and I don't notice any rough running - in fact during the last flight I was quite pleased with how smooth straight and level the airplane was running.

The syringe kits are not out yet so I calibrated and used my reloading scale, I could tell right away I was going to flunk as one float on the left carb (same side as the smells and overflow) was submerged and was noticeably heavy when I took it out of the fuel in the tray - even several hours after "drying out" (S/b calls for 2 minutes btw). Also the left cork float chamber gasket was apparently not installed correctly as there was a pinch in it when I removed it:

pb0w7.jpg


(the pair is supposed to weight 7 grams or less)

Here's the offending one (the "sinker"):

20q16qu.jpg


this one looks like it is going too....if a pair is supposed weigh 7 or less, I guess 1 should weigh 3.5 or less?

5bz59k.jpg


the "other side":

2505chs.jpg
 
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Wow John you just got your plane in the air! How long have you had fuel in the carbs before this tear down?
 
Wow John you just got your plane in the air! How long have you had fuel in the carbs before this tear down?

The plane has approx 8.5 hobbs, 5.3 flight...I just finished Test Card #3. The engine is in the affected range (although I think these floats sinking have been ongoing problems for more than a few)

Technically I had already installed and ran the engine a few times when the mand s/b came out - so I and some others I spoke with more in the know felt I had 25 hrs/60 days to comply....but the fuel smell and leaking carb dictated that immediate compliance was the better part of valor.

I guess that was the right call.
 
The question now is "What to do now?". There's no replacement parts designated and as you've noted, the test kits aren't even out there yet. I suspect I have a bad float as well as I get a whiff of gas occasionally, but I don't see a point in tearing everything apart waiting months for parts to come. Do you replace the float with another similar float until the new ones are designed?
 
Checked my floats a week ago as The engine is in the affected range.
7.1 grams for the two, so ok
This works much easier than the syringe job
 
The question now is "What to do now?". There's no replacement parts designated and as you've noted, the test kits aren't even out there yet. I suspect I have a bad float as well as I get a whiff of gas occasionally, but I don't see a point in tearing everything apart waiting months for parts to come. Do you replace the float with another similar float until the new ones are designed?

The way I read the SB you have to replace BOTH floats, even if they're the 'faulty' types (since the new ones have yet to be developed. Trouble is you can't find even used 'faulty' floats to replace until the new ones are available.

You also have to replace the gasket?but if that's pretty new why can't you check it and re-install? A fellow pilot installed a new one and it leaks!!
 
The thing that gets me - How hard is it to design a carb float and select a material that doesn't absorb gasoline? Any HDPE or inert Teflon variant should do. Ridiculous! But then again, they recently shipped fuel hoses that couldn't withstand fuel...

I mean - carbs have been around for more than 100 years!
 
Lockwood

I called Lockwood, and they are sending me 4 new floats (they will sell them separately) and two of their gaskets. Total cost is $173.76 inc shipping. They are also sending me a warranty form as well to ship everything back to them.

So we will see what they cover.

Total time to remove everything and test the floats took me approx 1 quarter of the Cardinals game. (45-60 minutes) - I had to unsafety the two air filters, loosen the carb clamp, undo the spring and then carefully unlatch the carb bowls (they are full of fuel btw).

3 of the 4 floats were bad. 1 was a sinker, the other two weighed close to or more than 3.5 grams dry.

The "other" method says that max allowable weight of both floats together is 7 grams.

But when I weight my good one - it is less that 3 grams (the video also shows that)....so perhaps all these floats are susceptible to saturation and possible sinking at some point or the other?

Based on my searches of past threads my guess is a good percentage of RV-12 owners have gasket/float/needle issues in their Bing carbs at one point or the other.

Not sure why Van's doesn't follow Lockwood's lead and replace those crappy cork gaskets on the float bowls as a start, but that's not my call. The worst part was that I thought I had a fuel leak somewhere so you start draining and tearing out fuel tanks and checking the fuel connections - all were fine btw.

My advice if you smell fuel while flying in the RV-12, start with the carbs - probably a bad gasket at the least, maybe a bad float or plugged needle or something else.
 
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Are the new floats that you are getting effected by the bulletin? If so, a true solution to this float issue could be a long time coming, and I can see a bunch of airplanes flat grounded before this is over. It may be time for an alternative fuel distribution system. I wonder if there is anything out there that will work for us??

Tom
 
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The question now is "What to do now?". There's no replacement parts designated and as you've noted, the test kits aren't even out there yet. I suspect I have a bad float as well as I get a whiff of gas occasionally, but I don't see a point in tearing everything apart waiting months for parts to come. Do you replace the float with another similar float until the new ones are designed?

Yep - the replacements are subject to the same 25 hrs/60 day check.

No ETR on the new ones as yet.
 
"I called Lockwood, and they are sending me 4 new floats (they will sell them separately) and two of their gaskets. Total cost is $173.76 inc shipping. They are also sending me a warranty form as well to ship everything back to them.

So we will see what they cover. "

Cactuspilot,

I thought the floats were about $100 for a pkg of 2 plus the bowl gaskets are about $9.50 ea. Are you saying the $173 inc shipping is their current price or a warranty price? That would be about $240. My engine is only about 4 months since new so is this something that would be included under warranty?

I thought Lockwood were out of stock on floats?!:p
 
"I called Lockwood, and they are sending me 4 new floats (they will sell them separately) and two of their gaskets. Total cost is $173.76 inc shipping. They are also sending me a warranty form as well to ship everything back to them.

So we will see what they cover. "

Cactuspilot,

I thought the floats were about $100 for a pkg of 2 plus the bowl gaskets are about $9.50 ea. Are you saying the $173 inc shipping is their current price or a warranty price? That would be about $240. My engine is only about 4 months since new so is this something that would be included under warranty?

I thought Lockwood were out of stock on floats?!:p

34.95 for each float. 15.98 for their gasket which is not cork and can be reused (ULS). I got a tracking number so I guess they are back in stock.
 
Cactus pilot:-

"I called Lockwood, and they are sending me 4 new floats (they will sell them separately) and two of their gaskets. Total cost is $173.76 inc shipping. They are also sending me a warranty form as well to ship everything back to them."

I just received 4 replacement floats and gaskets today from Lockwood. They're NOT the redesigned floats but can be used to replace faulty floats found during the 25/60 SB inspections.

Since my engine is new (July 2014 SLSA delivery) I too wondered about the warranty replacement. My mechanic asked Lockwood about this and they said to send in the warranty request when the redesigned floats become available.
So I'm wondering if Lockwood are going to warranty your replacement 'bad floats' now, or will they warranty replacing the 'bad floats' that came with your engine with the newly designed ones when they come out? Or both options….?
 
So I'm wondering if Lockwood are going to warranty your replacement 'bad floats' now, or will they warranty replacing the 'bad floats' that came with your engine with the newly designed ones when they come out? Or both options….?
Yes & Yes, warranty both! Hence the paperwork.;)(They are also sending me a warranty form as well to ship everything back to them.") Send paper work in with you first set of old floats. Then request new paperwork with redesigned floats.
 
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Yes & Yes, warranty both! Hence the paperwork.;)(They are also sending me a warranty form as well to ship everything back to them.") Send paper work in with you first set of old floats. Then request new paperwork with redesigned floats.

Okay, will do!! Thanks!:D
 
Just a note that the new old floats showed up today and a single float weighs between 2.50 and 2.70 grams dry out of the box.
 
We just saw our second set of floats fail. One float we found was sunk about 3 weeks ago and the set yesterday weighed 7.8.
 
Are you guys with the failed floats seeing any degradation of performance? Just wondering what the symptoms are.

Rich
 
The engine continues to run fine. As one or both floats lose their buoyancy fuel will start to come out of the small clear tube on the right side of the carbs, thus a fuel smell will occure at that time to let you know you have a problem.:rolleyes:
As more and more guys report failed floats here it looks like this is a much bigger problem than Rotax would like to admit.:mad: Because of the paper work you submit for your warranty refund there is no doubt that Rotax through their USA dealers know exactly how many failures are occurring. Lucky your engine continues to run as the floats fail.:(
 
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The engine continues to run fine. As one or both floats lose their buoyancy fuel will start to come out of the small clear tube on the right side of the carbs, thus a fuel smell will occure at that time to let you know you have a problem.:rolleyes:
As more and more guys report failed floats here it looks like this is a much bigger problem than Rotax would like to admit.:mad: Because of the paper work you submit for your warranty refund there is no doubt that Rotax through their USA dealers know exactly how many failures are occurring. Lucky your engine continues to run as the floats fail.:(

Keep in mind
that though it seems to run fine, if fuel is coming out the vent tube, then the engine is running richer than normal. The ratio of fuel delivery is influenced by the level of fuel in the float bowl. That is why there is a very specific adjustment for the float level.
 
Mine's not on the affected list, but in doing the PAP fuel pump test today, I've got fuel coming out of the right carb overflow tube. Not a good sign. :(
 
Mine's not on the affected list, but in doing the PAP fuel pump test today, I've got fuel coming out of the right carb overflow tube. Not a good sign. :(

Just because you are not on the list doesn't mean you might not have a problem.:p I had to replace one float in the Fall of 2010 with about 30 hours on the engine.
 
Just because you are not on the list doesn't mean you might not have a problem.:p I had to replace one float in the Fall of 2010 with about 30 hours on the engine.

Yes, that's what I'm thinking too, although there could be other reasons seeing I've had the engine for quite a while now. Either way, it's something I could have done without given the current situation with replacement floats.
 
ROTEC and HKS also use the Bing carburetor. I wonder if those guys are having problems. If not it begs the question as to why just ROTAX. I sold my HKS a couple of years ago so I lost touch with their support network.
 
Bing out sources the floats. They are a closed cell design. The outer coating is not a cure all sealer. The bad batch of floats was from the casting process. A bad mix that left some interior cells open to absorb fuel. Even over the years floats have sunk, but not with any regularity. From what I hear there certainly are some failing.
If your floats are fine and you are pulling fuel then you may just have a stuck float, need a carb sync because the engine shakes to the point the floats aren't working well or you need to adjust the float height. If the float height is too high the fuel just comes out the vent tube. To adjust the float height the carb must be off and upside down. The float arm height should be 10.5mm from the top edge of the float arm from the outside edge of the carb. You bend the small tab where the needle valve attaches. This isn't hard to do.
 
Reference 912 SB-912-067UL R1 carb floats. My engine S/N is below the affected S/N range by several thousand, and both cab S/N's are not in the affected range and is not affected by the SB. On the last takeoff the engine developed considerable roughness on takeoff roll and T/O was aborted. Same occurred on subsequent engine runs-all below 3800 rpm. Found fuel in rt drip tray. Removed both carbs and checked floats. Both the left and right carbs had one float sunk, with the right one the worst. NONE of the four floats were marked with the dot(s). Apparently the SB range needs to be expanded.

Be aware if you run into this situation you may have the affected floats.
 
The sinking float problem has been around for many years on the Rotax (just like other aircraft engines). If a part can fail to work as intended, eventually some will.
If you search the RV-12 forum here you will find a few instances of float failure back to the early RV-12 builders.
It seems that it became a much more chronic problem at a specific point in float production, so Rotax issued the S.B.
 
The new floats are the same as the old floats. No difference except Bing performs 3 test on them now and not just two. A pressure test was added and then if they pass they get the new little dots stamped on them. The floats haven't changed for many years. The last change many years ago was to make them alcohol resistant. The chance for a float to sink has always been there. So with 50K engines out there the small number of floats that has had an issue has been very small. Many floats make it to TBO. Bing never thought there was a float issue, that was Rotax. They wanted some way of double checking or triple checking if you like that phrase before they left the factory.

Same floats could have happened to anyone at any time, but for the most part they are quite durable.
 
Suffice it to say, you are making statements like, "So with 50K engines out there the small number of floats that has had an issue has been very small" as if you have actual data on the number of floats that are defective.

If you have an opinion, fine. If you make statements of fact, however, then please tell us where those facts come from.
 
Hi Jim,

How's that CT doing? Good I hope.

Direct from the Rotax master distributor for all the America's.
 
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I think the carb floats are like a bear stock market.....they all sink...eventually.

It's just a matter if they sink enough or fast enough for the owner to notice....or care.

The newer ones seem to be better constructed than the older ones, I'll take a picture if I get a chance for you guys to compare them.....time will tell though as I think the use of ethanol based gas adversely affects everything eventually.

Prob why Rotax has moved on to the IS. Carbs are so 1990's.
 
John,

I just took the ROTAX service and maintenance renewal courses. They talked a bit about the IS. It's pretty cool, but struck me as requiring a higher level of skill to troubleshoot and repair when it has a problem. It also requires a $1000 proprietary interface cable/module to read the trouble code from the computer. Old guys like me like stuff they can hold in their hand and cuss at when it breaks!😜

Rich
 
Loki/Lynn/Roger
I am not R100RS. I have never posted on this forum in other than the ID on this message.
You are revealing information about me that is not on my public profile. Why? What right or reason do you have to call me out for something I did not do?
I insist you delete the messages you posted in this thread allegedly about me.
 
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