What is this stuff in my gascolator?

[Vance Harral]

Opened up the gascolator at the annual inspection today and found a significant amount of what I'll call "dryer lint" on the screen.  Photos below.  Note that the first photo with the material resting on the screen was taken after I'd already run my finger across it, which caused it to roll up into the snake shape shown in the photo.  Originally it was evenly caked across the whole screen.

The stuff was caked on thick enough to be disconcerting - seemingly enough of it to impede fuel flow, though we haven't seen any fuel pressure or fuel flow issues since the last annual.  It's red in color, and looks and feels like cotton fibers.  Couple of guys in the shop speculated it's from a fiber washer or gasket, but as far as I know there's nothing like that in the Mooney fuel system.  My initial guess was fuzz from a red shop rag, but I don't really think there's a shop rag in the tanks or elsewhere in the fuel system.

I'm pretty sure this isn't decaying tank sealant, for two reasons.  First, the texture doesn't match what I'd expect of tank sealant.  It's not plasticized, rubbery, or gelatinous - again, it's fuzzy like cotton.  But more importantly... and here's where it gets weird... all the material was on the engine side of the screen, not the fuel tank side.  In other words, it seems like the material is settling into the gascolator from "downstream", opposite the normal direction of fuel flow.  I'm not sure how that's possible, but 100% of the material was on the top side of the screen (fuel from the tanks flows through the center of the gascolator to the bottom cup, then up through the screen, thence to the electric fuel pump).

Upon discovering the problem, we drained about a half gallon from each tank through the gascolator, and that fuel came out as clear and blue as the pool at a 5-star hotel.  Then we cleaned out the gascolator and screen, reassembled, and used the boost pump to run another half gallon through the gascolator and boost pump out of each tank, through the hose that feeds the fuel servo.  That too came out nice and clean.  So it's a mystery where the stuff came from, and we can't reproduce it.

What says the Mooneyspace hive mind?  Any and all speculation is welcome.

 

 

Edited April 8, 2021 by Vance Harral
fix typos

[carusoam]

Holy furball Catman!

No skeleton to go with that?

Expect that came from a fuel tank somewhere... and...  you may have neighbors that are interested to know what you found...

Of course, it could have come from anywhere you got fuel over the last year...

If you have a JPI with fuelP data... it may be interesting to review the data to see if there is any differences over the past year... (unlikely to show, because it is well before the pumps... but, if the fibers have moved down stream, it may give you a hint...)

PP thoughts only...

Best regards,

-a-

[RLCarter]

they need to change the Fuel Pump filter at The FBO where you buy gas at.... a buddy had the same crap in his Cherokee from his local FBO, when they pulled the filter it was coming apart

 

[Vance Harral]

The idea that it came from a fuel provider is an interesting one.  That would be a one-off event, consistent with finding junk in the screen, but none when draining the tanks or pumping through the electric pump.

Still, I'm mystified by the fact the material is on the downstream side of the screen, opposite side from the fuel tanks.  If the contaminant came from or passed through the fuel tanks, I would have expected to find it on the upstream side of the screen.

Might be a good idea to get a look at the pickup screens in the fuel tanks in any case.  Any way to do that safely without completely gdraining the tanks?  I have a cheap endoscope I can feed down there.  I don't mind if doing so winds up killing the endoscope, but I wouldn't want material sloughing off the endoscope to contaminate the fuel or cause other problems.  I might try draining some fuel into a bucket and putting the scope in there first as an experiment.

[carusoam]

Vance,

Something is defying logic...

If the material could be easily scraped off the screen...

And fuel flow is going from the tank side toward the engine side...

That material would have to come from somewhere, and then get pressed against the screen... against the FF...

 

Say again what side of the screen that was on?

I think you may have an error in your description of where the fuel enters the separator...

I believe fuel enters above the screen, gets drawn towards the engine below the screen, and gets dumped out the bottom by the sump valve...

This way gravity and fuel flow will continuously keep contaminants on the screen...

Check your details closely...

I’m only using PP logic, and may have missed an important detail...

Best regards,

-a-

[Vance Harral]

It's certainly possible I misunderstand how the fuel selector works, but I don't think so.

Below are a couple of photos of the Dukes fuel selector/gascolator in our airplane.  These are taken from underneath the airplane, looking up.  The feed lines from the tanks are at the top (i.e. at the "back" of these photos), while the line to the boost pump is at the bottom (the "front" of these photos).

The screen is beneath the level of all the supply and feed lines.  With the bowl removed, when the fuel selector is moved from OFF to LEFT/RIGHT, fuel drains through the center of the unit, not through the screen.  It comes out the four small holes in the center post that you see in the photo, and fills the bowl.  It must then flow up through the screen, to exit out the boost pump line, and on to the engine driven pump.  The arrangement appears to work like a P-trap on a sink.

The gunk was entirely located above the screen (or "behind" the screen relative to these photos).  That's the engine side, not the tank side.

 

[ArtVandelay]

They had problems with electric pumps coming apart and added a screen after the pump, did you check this screen?

[Vance Harral]

5 minutes ago, ArtVandelay said:

They had problems with electric pumps coming apart and added a screen after the pump, did you check this screen?

I'm about 95% sure our airplane does not have that post-boost-pump screen, because we have a replacement Weldon boost pump.  But I'll double-check tomorrow.  Thanks for the tip, any and all ideas are welcome.

[carusoam]

Vance,

I think I may have an idea...

1) Does that stuff sink, float, or both in 100LL?

2) Got any of it on the fuel screens in the tanks?

3) This is weird enough to call in the big cannon... @M20Doc (fiberous material on the M20F fuel separator screen)

Best regards,

-a-

[PT20J]

Did someone else clean it last time? Perhaps they wiped things with a shop rag and left lint behind. If it were mine, I’d check the fuel servo finger screen and the Dukes pump filter if it has one and run it for 5 hrs and check the screens again.

Skip

[Vance Harral]

10 minutes ago, PT20J said:

Did someone else clean it last time? Perhaps they wiped things with a shop rag and left lint behind. If it were mine, I’d check the fuel servo finger screen and the Dukes pump filter if it has one and run it for 5 hrs and check the screens again.

I was the last person to lay hands on the screen a year ago, and no I did not not clean it with a shop rag.

I'll work with the shop tomorrow to check the fuel servo finger screen, thanks for the tip.  Checking it again after a few hours' operation is definitely on the agenda.

[Vance Harral]

15 minutes ago, carusoam said:

1) Does that stuff sink, float, or both in 100LL?

Don't know.  But we saved it, I will check tomorrow.

16 minutes ago, carusoam said:

2) Got any of it on the fuel screens in the tanks?

The plan is to look.  Hoping not to have to drain the tanks to do, so, but can do that if necessary.

 

[Bolter]

Brainstorming idea...are these pumps using ball bearings with phenolic cages?  If the bearing seal is leaking fuel through the bearing, could it break down the phenolic back into fibers?

[EricJ]

It may well be red shop-rag material.   If somebody wiped down the inside of a tank somewhere with a shop rag it could easily wind up in your screen.   I've heard of this during tank cleaning/prep during repairs and reseals, too.   There's opportunity for contamination at many places along the supply chain, but the delivery system and the tank itself may be the most common.   

 

[Raymond J1]

2 hours ago, Bolter said:

Brainstorming idea...are these pumps using ball bearings with phenolic cages?  If the bearing seal is leaking fuel through the bearing, could it break down the phenolic back into fibers?

Steel cage for the bearings (Duke motor)

[A64Pilot]

A way to test if fuel contaminants are biological is to put bleach on it and see if it reacts,  changes color. Jet fuel and Diesel trick because they can get asphaltanes and make some think they have “bugs”

Does anything grow in Avgas? I don’t think anything does?

‘Fuel truck filter breaking down is the most logical to me, but I cannot explain it being on the wrong side of the screen. Anything that happens to a motor can’t get into the fuel

[201Mooniac]

I had a similar issue many years ago and tracked it back to a fuel filter problem from a fuel truck.  While the rest of the fuel in the tank seemed clean, we set a sample aside and let it evaporate and the fibers appeared.  Once the screens were all checked and cleaned, everything went back together and never had a problem since.  In that case though, I did have a fuel pressure issue on take-off that necessitated and immediate return. Luckily, the fuel pressure was still enough to pass sufficient fuel tot he engine that it was mostly a non-event.

[Vance Harral]

18 hours ago, EricJ said:

It may well be red shop-rag material.   If somebody wiped down the inside of a tank somewhere with a shop rag it could easily wind up in your screen.   I've heard of this during tank cleaning/prep during repairs and reseals, too.   There's opportunity for contamination at many places along the supply chain, but the delivery system and the tank itself may be the most common.   

 

We did have a patch job done in March of 2020.  This stuff wasn't in the gascolator in April of 2020 at last year's annual.  If the shop that did the patch job left shop rag material in the tank, it took more than two months to migrate to the gascolator.  But perhaps that's not implausible.

[Vance Harral]

15 hours ago, Raymond J said:

Steel cage for the bearings (Duke motor)

Ideas that it may have something to do with the boost pump are interesting.  We have the "new" Weldon pump, but it was installed over 15 years ago, and has about 1000 hours of service (a lot less time actually in operation, of course).

[Vance Harral]

19 hours ago, carusoam said:

Does that stuff sink, float, or both in 100LL?

We checked this today.  It sinks like a stone, which makes it all the more mysterious that it was on top of the screen rather than the bottom.

The shop IA got tied up today and hasn't really had a chance to look closely and consult.  It'll probably be Monday before he can really dig into it.

[carusoam]

If it sinks that readily...

expect that there may be some in the corner of the tank, lower than the sump drain...

If it was in the tank at all...

PP thoughts only...

-a-

[Yetti]

Finger screen droppings when we first got the plane.   As noted here the orange o ring was a very old o ring.

er screen

[FlyingDude]

A little off-topic questions:

- do you replace that gasket in the gascolator every time you open it?

- how do you open that panel without retracting the nose gear? We opened mine during gear swing.

Thanks guys

[Yetti]

Undo the rod on the gear nose door.   Make sure all the washers go back in the same way.

 

LASAR has a kit with the gasket and the fancy washer with rubber vulcanized to it.    Be mindful of the bolt tourque spec.  Some are mislabled.  There is a SB on updating the spec.

[FlyingDude]

22 minutes ago, Yetti said:

Undo the rod on the gear nose door.   Make sure all the washers go back in the same way.

 

LASAR has a kit with the gasket and the fancy washer with rubber vulcanized to it.    Be mindful of the bolt tourque spec.  Some are mislabled.  There is a SB on updating the spec.

Thank you