Red particles in float bowl, cause unknown.

Situation / Problem:

1st engine start/test:
The left carb was overflowing before cranking the engine, I popped the float bowls to inspect the floats. The engine ran fine afterwards.

2nd engine test
2 weeks later we experienced the same problem on the right carby. We also noticed a lot of debris of black and red particles in both floatbowls post the engine run.

Test3:
A week later I prepared for the third engine run and the engine only fired on the left cylinders, both ignition circuits A and B were working in isolation. After popping the float bowl again the engine fired on all cylinders. A lot of red particle debris continued to accumulate in the float bowls.

The engine has a logbook entry that the pressure side fuel hose was replaced at some point before I received it in Australia (ASB 912-061).

Gascolator screen has no debris. Finally flushed the fuel lines by taking out the banjos at the carburettors and ran the electric fuel pump. After 5 liters of flushing I still have primarily red particles coming out. Looks like firesleeve type particles / debris.
Could the problem be related to the ASB 061 fuel hose replacement?

I have no idea where this stuff is coming from, gasc screen is fine, so can only be the hose from gasc to mech fuel pump or hose to clamp block / hose to carbys.

Appreciate any thoughts / experiences from other builders.

Thanks

Steffen

This is what I would do here in the USA. I would call one of the 3 Rotax dealers and explain to them what you have stated here. Then I would ask them if I could get a complete set of new hoses, all of them covered under warranty. Most likely they would charge me for the new hoses until I sent them back the old set for inspection by their own techs. Then after they verified that the hoses were bad they would refund me the cost of the new hoses. From the info you provided I would replace every single hose on that engine. Is there a Rotax dealer in your area you could talk with?

Steffen----can you post a picture of the debris? The 'red' particles sounds like RTV sealant, since there shouldnt be anything else red in the fuel system. The RTV shouldnt be able to get into the liner of the hose, unless someone was sealing the firesleeve and pulled the hose off the barbs at the same time ( not good). Then its a possibility. The black residue 'may' be liner material, but I dont want to speculate. But----its happened before.
Thats one of the reasons we built the teflon hose replacements for the Rotax 912.
Tom

Steffen....

As Tom mentioned, debris in the hoses on the 912 engine has been a thorn in the side of Rotax. That is one of the reasons we developed the 912 retrofit package. We wanted to ensure a high quality solution that eliminated any possibility of rubber debris in the lines.

In addition, by eliminating all banjo and barbed fittings in the engine, we are able to provide a more "standard" aircraft setup.

If you have any questions, please let us know.
Steve

Thanks for the responses.

After contacting Kodiak they advised it is best to replace the fuel hoses and fuel pump (under warranty). See pictures below of debris in float bowl and some weird stuff inside the fuel pump. Still not sure where the red debris originated, and Kodiak didnt want to speculate.

The teflon hoses seem like a great option, but I probably wait a little while and will make a living with the standard hoses, hoping they wont cause anymore grief.

I assume the warranty work will be done by Bert Flood? Did they have any comments?

That corrosion is water damage and the red specs because of their size, shape and color look like part of the diaphragm. I have seen that type of water damage twice before. I think the old pumps did a better job of handling moisture.

Have you considered pulling the fuel hoses and blowing them out with air the remove any particles?

Dust in new hose assemblies at manufacturing plants are a prime source of dust and contamination for hydraulics. Imagine a large hydraulic excavator with lots of hoses. (ok, where is he going .? .? )

The way these are cleaned is to take a plug of foam rubber and blow it through the hose both directions. This will clean off the walls.

Similar problem

I recently completed the 25 hour inspection on the engine and found this debris in both carb bowls:



It appears to be identical to the debris reported by the OP. Looks like I will be finding out how good Rotax support is in Australia, assuming these particles are coming from either the fuel pump diaphragm (main suspect?), the hoses, or both. The fuel pump is the later version, and the pressure side fuel hose on the fuel pump was replaced by an A&P before I received the engine from Vans. Gascolator was clean as a whistle. Apart from the OP, has anybody else come across this problem?

This should NOT be RTV sealant from the firesleeve. Cant get RTV into the hose by sealing the firesleeve---unless someone tried to seal it BEFORE clamping it to the banjo. Highly doubtful. Like Roger said in an earlier post, may be from the diaphragm. Black residue---thats another story, and quite possible to be liner debris.
Tom

Debri in carburetor float bowls.

A friend of mine just had the same problem in a new Rotax engine he installed in a Titan Tornado. Aircraft was all signed off and ready to start flying when he pulled the carb float bowls for a final check. He had numerous ground runs on this engine with 92 Octane Non-Ethenol fuel. He pulled the fuel pump apart and found it was corroded inside or had some type of coating that was sluffing off.
His research has indicated many problems with this factory installed pump & is considering a Billeted Fuel Pump for his engine.

Oh Sink where art thou!

Rgmwa, you should consider getting a new fuel pump to. May take your old one appart and inspecting it. Any chance you may have had some water in your fuel or how about mositure build up in that shipping container while at sea enroute.

Hi John,
I contacted our Rotax distributor in Australia this morning. The person I spoke with hadn't come across the issue before, but said he would discuss it with their main technical guy. I sent him the photo and a link to this post, and ordered a new fuel pump. The red colour of the particles seems to point to the diaphram as a more likely source than the fuel lines. That's what my local Rotax A&P thinks anyway. Hopefully it will be a warranty job, but we will see.

I received my engine in 2012 and it sat in dry conditions in its shipping crate until it went into the plane sometime in late 2013. I don't have the exact dates to hand just now. First start was in December 2014, and the engine currently has about 32 hours on it. I guess atmospheric moisture is always a possibility, although the engine seemed well crated and sealed for the ocean trip, and our climate is typically not very humid. Water in the fuel seems unlikely since I'm still around to report on the problem. Anyway, when I find out some more, I'll post it here.

RGMWA,

Curious. Do you use gas with ethanol in it?

BigJohn,
No, I'm using 98 (RON) unleaded, ethanonl free. Ethanol blends are still relatively uncommon in Australia. Our standard fuels are 91, 95 and 98 RON.

Happy Holidays everyone

First the corrosion in the fuel pump.
The newer Corona fuel pumps are made of a different material and MFG'd differently than the older AC and Pierberg pumps. If water gets into the Corona pump it can cause that whitish looking corrosion and if left in for prolonged periods moisture can cause some mild pitting. We have already seen this. If this is just some minor whitish coloring it won't hurt anything. This can also happen to the carb bowls because of the aluminum metal. Water can collect in the bottom and cause the white powder and pitting. One thing ethanol laced fuels do is keep moisture trapped in solution and just burns it through the engine. 100LL and straight auto fuel don't do this and moisture can pool.

p.s.
The Corona pumps were never made to take apart and reassemble. I wouldn't worry about them unless you have a constant discharge from the drain. These pumps can and do weep sometimes. So if you see a few drops (not a constant discharge) from the drain that can be normal. Some are dry all the time and some are not.


Just a thought;
The red particles in the carb bowl can from from a few different sources.
If using fire sleeve with "End Dip" on the fire sleeve ends then this would account for the red particles because it was applied before the hose was pushed over the fitting. If you used a red silicone maybe someone either applied it before pushing the hose on the fitting or after that person applied the silicone remove the hose, even for a moment, to correct something and then pushed it back on. It may not even be a red silicone and possibly a thread sealer from somewhere else in the system.

On a new engine or an engine that has major work done on it or a hose change it is possible to see a few particles now and then. If it is a one time deal and tiny I usually don't worry and just dump them and allow a little fuel to flush out the carb with the pump with the bowl off and into a rag. If I keep seeing debris and or it is large in nature (enough to plug the main jet) then I would look much more closely. Debris from fuel tanks can be common on new aircraft and that's why we should have fine meshed fuel filters inline. Even then there can be very fine debris that can make it to a carb bowl from anywhere in the fuel system after the first few hours on a new engine. Carb bowls are a good place to inspect at the 25 hr. warranty inspection and only takes a few minutes.


Hi Jetguy,
Did this help?

Rgmwa,
You might want to check your Engine log book and see if Vans Replaced your fuel hoses before they shipped the engine. There were some serial numbers that had a recall on their fuel hoses. Check this link and compare your serial number to see if it applies to your engine.

http://rotaxnews.net/wp-content/uploads/2012/06/d05141.pdf

Red = Rust !

WE had the same problem at our home field with underground tanks of steel.
Rust in particles smaller than 1 micron got through the filters at the pump.
It was almost a fatal crash of a Christen Eagle because the "rust" got to the
fuel injectors and you know what happened. They shut down the pumps and cleaned the fuel farm tanks. Yes, they were old.

Sorry, just thinking out of the box......
John

Jetguy,
Thanks for the reminder. Yes, Vans carried out that ASB before they shipped the engine.

Sink,
The debris we found was more than just a few particles. I don't want to replace the pump if it's not necessary, so we might try some more ground running first and check the bowls again. My plugs were pretty black too suggesting the engine is running too rich. Any possible link between that and a failing diaphragm?

Are the fuel caps painted red by any chance? If so, it could be paint chips from the caps.

Just a thought.

Bevan

Bevan,
No - standard cap and the gascolator is clean.

black plugs

Hi two plugs will be really black and the other two will be black especially after extended ground runs The engine will run very rich on two cylinders at idle or ground runs but will lean out when actually flying

The red particles must be from the inside the hoses or from the diaphragm as they are only appearing after the gasculator screen

Replaced fuel pump

We replaced the fuel pump today and opened up the old one. The diaphragm, which comprises three leaves of thin red rubber, seemed fine. However, there was some corrosion deposit on the inside of the pump housing and also on the plate in the centre of the diaphragm. The corrosion surprised me as the engine only has about 30 hours on it, all using 98 RON unleaded mogas.

However, we found nothing to explain the rubber particles in both carb bowls that I reported previously. I can only surmise that these were shed from the faulty pressure side fuel hose that was replaced by Van's A&P before the engine was shipped (ASB-912-061R1). In hindsight, I should have checked the bowls soon after first engine start instead of at the end of my 25 hour Phase 1. Lesson learned! Since initially cleaning the bowls, the engine has run for about an hour, and a second check today found the bowls were clean.

Robert, thanks for a great follow up on this problem. Maybe you could send those photos to your Rotax Field rep for Australia.

rgmwa said:

I can only surmise that these were shed from the faulty pressure side fuel hose that was replaced by Van's A&P before the engine was shipped (ASB-912-061R1). In hindsight, I should have checked the bowls soon after first engine start instead of at the end of my 25 hour Phase 1. Lesson learned!

Click to expand...

I don't think any of the material in any of the hoses is red.

I am pretty sure that checking/cleaning the float bowls is one of the check list items in the PAP, to be done after flushing fuel through the fuel system, but before first flight.... but I could be wrong.

Quote from PAP page G6-1 before first flight:

Remove any remaining fuel by removing gascolator bowl and running electric fuel pump until no more fuel comes out. Note presence of any debris in gascolator bowl and clean screen then re-install gascolator bowl and safety.

Remove carburetor bowls and check for debris.

Click to expand...

John: I'll send the pump back to our Australian Rotax distributor. If I'm lucky, they might refund me the cost of the new one. I don't think the corrosion deposits would necessarily have caused a problem, but I'm happier knowing that pump is no longer on the engine.

Joe and Scott: I checked the gascolator as per the PAP and again at the 25 hr mark and it was clean as a whistle. However, I missed the initial carb bowl check in the PAP - my mistake. I agree the fuel hoses all appear to be black, so I really don't know where the reddish particles came from. Anyway, they're not there any more, and I'll be keeping a close eye on the bowls from now on.

The corrosion in the picture is from water in the fuel. The new pumps are aluminum and water shows up this way. The old pumps were steel and water didn't affect them the same way. Slight corrosion isn't an issue. Heavy corrosion is. One thing about ethanol fuel is water is absorbed and runs right through the engine and you would never know it. It also helps with this corrosion issue as the water is held in solution.


Hi rgmwa,

Did you find red fuel pump diaphragm particles missing from the diaphragm?
If it was smooth everywhere and the edges were all intact this may not have been the red particles in the carb bowl? Just a thought to keep your eyes open for a while. Small enough particles will go right through the carb main jet. That said even the smallest particles can get in the idle jet and make idling rough and the carbs won't sync correctly.

Hi Sink,
I examined the diaphragm leaves carefully tonight using a loupe and good lighting. The surface has a dimpled texture but looked to be in good shape, including the edges of the rubber. No signs of deterioration anywhere that I could see, although the rust buildup in the centre of the plate looks pretty ugly when magnified. We checked the idle jets, but they were clear.