Heavy Floats

[FlyingMonkey]

9 hours ago, Jim Meade said:

Ethanol was introduced as an alternative to MTBE which was used to meet clean air standards.  Get rid of the clean air standards and ethanol will go away.  Yes, I am a corn farmer.  Should we start a separate thread to discuss government subsidies and corn production?

 

Not trying to start a fight, just gave my opinion.

[Jim Meade]

The government indirectly subsidizes corn production but the government does not directly subsidize ethanol production.  (And for what it's worth, I'm one of the 1% of farmers who refuses to accept any government money of any kind, including subsidized crop insurance, disaster payments, cost share of conservation projects, ...not one penny of government money).

Many state governments set standards which make it difficult to buy gasoline without ethanol (which could come from cellulosic, sugar beet, etc. sources except that corn is more cost-effective).  I have no trouble in Iowa buying 91 octane mogas without ethanol but I understand in some states that's more difficult.  In fact, I routinely by 93 octane nonethanol gas for my FD.  But I'm happy to burn 10% ethanol in my cars and trucks - save the hassle of adding isopropyl alcohol in the winter.

There is a lot of misinformation out there about ethanol and subsidies - rather like the misinformation extant on Covid-19.

[GrassStripFlyBoy]

UPS truck just arrived.  Nice looking items, the individual weights are 2.6 / 2.7 / 2.7 / 2.8 grams.  Matched up the 2.6 with the 2.8 into a pair, and the two 2.7's, both sets show 5.5g combined weights.  

[Jacques]

great, glad I saved you some $$

you owe me a beer

[GrassStripFlyBoy]

Earlier in this process I emailed Spruce inquiring on weights / design revision / stock status.  The picture showed the later design but you know how that sometimes goes.  I pulled the trigger anyways, and this reply just came back.  Thought it was worth documenting here in the trail:

Answer: Marvel Schebler got back to me on this with, "This is a complicated subject. I would like to first point out that the Rotax bulletin specifies 7g max; for a set of floats that are manufactured by a different company, manufactured out of a different material and carry a different part number. Neither Marvel-Schebler (MSA) nor MS80-430 have been mentioned in the Rotax service bulletins pertaining to floats. For these reasons, MSA maintains the 7g max does not apply to the MS80-430 floats. That being said, the first offering of the MS80-430 floats were supplied with the occasional set weighing more than 7 combined grams. Not to get too detailed about our findings, but yes the original run of the MS80-430 floats were sometimes heavier than the specified weigh for floats produced by Bing. We did have a few operational complaints by customers; conditions that we were not able to verify/duplicate in our facility. We had FAR more floats returned because of out of the box weight or because of internet speculation, than we had floats returned because of an operational complaint. The vast majority of the floats that were returned had never installed. MSA did slightly tweak the shape of the float to bring the weight down to at or below 7g per pair."

[Roger Lee]

The float weight comes from Bing and they used to be right around 5.9 +/- grams out of the box with the old style floats. When that company stopped making the floats and a new company started that's when all the float issues started because of the float composition.  The float weight has to do with fuel level and pressure exerted on the float armature that regulates the fuel flow and fuel level. The heavy floats allow the fuel to rise to a flooding level. Currently the float armature height is set at 10.5mm from Bing and this coincides with the proper float weight and buoyancy. The new float weights are around 6.3 grams +/- out of the box. So .7 tenths of a gram is a fairly small amount to play with.

[robjahnke]

This topic has been discussed ad-infinitum for many years  It's time for the CI on my 2006 CTSW (ELSA) so I was looking up the spec for float weights. After reading numerous posts on this forum and then going over to the Vans forum "Sinker Club"  https://vansairforce.net/community/showthread.php?t=166138&page=24 and reading  250 posts and seeing multiple service bulletins from Rotax on the subject (the latest in December 2020), it is obvious that there is a problem with the Bing 64 floats. The most interesting post referred me to a motorcycle guy's  site and 12 years of testing Bing 64 carb floats. https://bmwmotorcycletech.info/bing-floats.htm. Motorcycles have had the same problem. So this isn't a Rotax problem per se and it's not a new problem. It's a Bing Carb problem.

The root cause of the problem is evasive, but it appears that fuel additives play a significant role. Many people have no problem for years. But others have joined the "Sinker Club" multiple times. Then I discovered the Marvel Schebler MS80-430 Blue Epoxy floats. My first impression was that a solution was finally at hand. Then I read on and discovered a problem. They typically weigh just over the 7g limit and they sink farther into the fuel, thus raising the fuel level in the bowl. Then this model was removed from the market by MS ... with a promise of a new design. Many months later (December 2020) they came out with the new design, which removes some excess material from the top of the float with a new shape and brings the weight down to 2.8-2.9 g each (5.6-5.7 g for the pair).

One of the Vans forum members got this response from Marvel Schebler on December 7th 2020:

I just got off the phone with a gentleman named Mark at Marvel Schebler as I had some questions about their Rotax floats, part number MS80-430. The original Rotax/Bing replacement floats they made were the exact shape and size of the Rotax/Bing float and they were heavier then the 7 gram/pair limit and people didn't want them. He told me they were heavier because they are made from a different material. They have since redesigned the float and it has a different shape and they now come in well under the 7 grams per pair limit.

Yes, I did ask him about ethanol in MOGAS because I run MOGAS only but I can get ethanol free MOGAS at an airport about a 10 minute flight from my home airport. He tells me that the floats have been tested with every type of fuel you can imagine with no negative effects. This was a tech and not a salesman. Is it true? I have no hard evidence it is but they must know that Rotax users use fuel with ethanol in it.

If anyone has questions or is unsure I urge you to contact Marvel Schebler yourself and ask them. Their number is 855-672-2272 and they are located in North Carolina.

The floats in my 2006 CTSW are original and still come in under 7 grams. The floats in my 2005 Titan Tornado are also original and come in under 7 grams. Both have been run exclusively on 91 Non-Oxygenated Mogas in Minnesota until last year when I switched to 94UL Avgas (Swift Fuel).  It seems that some people see their floats last a long time (years), but then over a short period, they become "Sinkers".

So I decided to order two pair of new style MS80-430 Blue Epoxy floats for my 2006 CTSW and replace them this week when I start the CI. I got mine from Mcfarlaneaviation.com 
https://www.mcfarlaneaviation.com/products/product/MS80-430/ for $140 + S&H/pair ($301 total for both carbs). The picture on the website shows the older style 7g design but the installation instructions show the new design. At this time, these can only be used in an ELSA. I would hope that Rotax/FD would approve these as a general replacement for SLSA at some point ..... if they truly prove to be the solution. 

 

 

 

 

[GrassStripFlyBoy]

Hey Rob,

Good to know McFarlane is shipping the new revision, I had considered ordering from them but I assumed the discounted pricing and the old style pic would have the original type arriving, and Spruce is a predictable UPS delivery for me and I wanted to fly this weekend, so chose them.

A bit of an update, flew both Saturday and Sunday.  The engine is running as smooth as ever, I'm sure the mechanical balance had a bit of impact as well, no regrets going with these MS floats.

[Roger Lee]

Food for thought:

Legally you can't use Marvel floats in an SLSA unless you have an LOA and I know of none. Even in some ELSA's depending on how your operating limitations are written. If you had an incident you'd be toast with the FAA and your insurance company. Could even open you up to legal litigation if someone gets hurt.

[Tom Baker]

5 hours ago, Roger Lee said:

Food for thought:

Legally you can't use Marvel floats in an SLSA unless you have an LOA and I know of none. Even in some ELSA's depending on how your operating limitations are written. If you had an incident you'd be toast with the FAA and your insurance company. Could even open you up to legal litigation if someone gets hurt.

I'm pretty sure ICP provided one for a customer with a Savannah.

[procharger]

Its time for this float crap to end somebody F fix this. Rotax owes us all free floats???

Been going for years. BS  Once the floats get a little heavy do they continue to get

heavier or stay about the same weight? Mine got a little heavy so I readjusted the float

level year or so ago and it has stayed the same ever since I keep an eyeball on it

ever so often.

[robjahnke]

I have the MS floats from McFarlane (new style - blue epoxy) but I did not install them at this time, so I will not be able to report how well they last. Why? Because I weighed my floats again at this annual condition inspection. The left side comes in at 6.1 grams and the right side comes in at 5.94 grams. Since these floats have been in the airplane since new (2006) I do not feel compelled to throw them out. From 2006 - 2015 the fuel used was 91 Octane Non-Oxygenated mogas (Minnesota summer mix for the most part). The airplane was not flown from 2016-2019. Since 2019, the fuel used is 94UL (Swift Fuel - same as 100LL without the lead). 278 TTAE.  I have a 2005 Rotax 912ULS with the same fuel usage profile and roughly the same float weights (102 TTAE).  So I will carry the MS floats in the airplane as spares. I think they have the potential to be the "ultimate" solution, but only time will tell.

Based on the research and discussion in my previous post, it appears the most likely cause of "Sinking" floats is additives in the fuel (both known and unknown). This could easily explain why someone like me with "old original" floats and many others, have not seen "Heavy Floats".  But ... if I were to switch fuels, or just get a different batch of the "same" mogas but with unknown or different additives, I could become a member of the "Sinker Club".   . This article  (https://bmwmotorcycletech.info/bing-floats.htm  has convinced me that the true cause of sinking floats may never be precisely known because of the large number of variations in fuels and additives.  So it may be that Rotax/Bing thinks their design is good, only to find each "new" design is not able to handle all of the unknown combinations of fuels. However, they have not really done much to improve the design either. At least the MS design (blue epoxy floats) is a significant change that has the potential to eliminate the sinking float problem. Only time will tell.  AV gas is subject to much stricter controls than mogas, so I am anticipating (hoping) that I will not join the "Sinker Club" by continuing to use 94UL. I will continue to weigh my floats at every annual, and I will have a set of MS floats on hand if there is a problem along the way 

I will be anxiously awaiting reports, good or bad, about people's experience with the MS floats.

Rob

[Roger Lee]

It isn't fuel additives that caused the issue. It was a change in the float Mfg and they couldn't get the float composition correct. I think and hope this brand new float with the "R" on it finally fixes the problem. Different Mfg. If you have older floats they may never get heavy and last a few thousand hours. Leave well enough alone in this case.

[BravoFoxtrot]

robjahnke: Since 2019, the fuel used is 94UL (Swift Fuel - same as 100LL without the lead).

Where are you getting your Swift fuel from? I don't see anything local.

[robjahnke]

 

Info about Swift Fuel 94 UL https://www.swiftfuelsavgas.com/

Map: https://www.google.com/maps/d/u/0/viewer?mid=1fNC9vcS4U3u15y5FxBZ_d6Mjqvw&ll=40.805955463244274%2C-94.37862123125001&z=5

The map shows where 94UL (Swift Fuel) is available in the US. I get mine at Fleming Field (South St. Paul KSGS). I live about 80 miles northwest and make 2 - 3 trips a year to haul it in portable gas cans. For me it works, but it's not a viable option for most people. Let's hope it becomes more widely available. 

[BravoFoxtrot]

Ok, thanks. I have been waiting for their network to expand, but it hasn't happened yet. I use the map when planning cross-country flying, but that only works going east from the midwest.

[GlennM]

I get two 350 gallon bulk containers of Swift fuel 94UL delivered to the house.  Then, I have a tank in the bed of the truck to fill the plane.  When empty, they are freighted back to Swift fuel and new, full containers are dropped off.

They price the fuel by the weight and include the shipping costs (both ways) in the price.  The way I do it, with only two containers at a time, the shipping costs make the price per gallon higher, but it is still less than my home airport at $5.75/gallon.

I use it in my race car, too! 

[Warmi]

I got 3 airports around here with Ul94 fuel ( Chicago ) and last time I check it was going for $4.30 - a lot more than the pump gas but still reasonable.

[okent]

I'm guessing the shelf life is much longer with the swift fuel.  I called them a few years ago and they basically didn't want to talk to me about shipping a few drums.  Have they changed their stance on this?

[Skunkworks85]

2 hours ago, okent said:

I'm guessing the shelf life is much longer with the swift fuel.  I called them a few years ago and they basically didn't want to talk to me about shipping a few drums.  Have they changed their stance on this?

I tried a year ago too. And they where not interested in selling me less than 500 gallons