fibers in fuel screen

[mhrivnak]

Continuing troubleshooting of a fuel flow issue, today we found a wad of fibrous material in the fuel servo screen. Where could this come from? Could it be deteriorating fuel lines?

It was a solid mass when it was pulled out of the screen. I pulled it apart a bit to get a sense of the material.

This is only about 4 tach hours after the servo was overhauled, and 2 hours after the mechanical fuel pump was replaced. My impression is that the overhaul shop was very meticulous about the servo overhaul, so it seems unlikely this material was in the screen when it came back from them, which suggest it accumulated quickly.

The gascolator was whistle-clean at annual, 17 tach hours ago, but I did not re-check it today (maybe I should go do that tomorrow...). Considering that the servo screen caught this, it seems unlikely it would have passed through the gascolator screen.

[EricJ]

Definitely check the gascolator screen and the filter at the electric pump if you have one.  

[LANCECASPER]

2 hours ago, mhrivnak said:

Continuing troubleshooting of a fuel flow issue, today we found a wad of fibrous material in the fuel servo screen. Where could this come from? Could it be deteriorating fuel lines?

It was a solid mass when it was pulled out of the screen. I pulled it apart a bit to get a sense of the material.

This is only about 4 tach hours after the servo was overhauled, and 2 hours after the mechanical fuel pump was replaced. My impression is that Airflow Performance was very meticulous about the servo overhaul, so it seems unlikely this material was in the screen when it came back from them, which suggest it accumulated quickly.

The gascolator was whistle-clean at annual, 17 tach hours ago, but I did not re-check it today (maybe I should go do that tomorrow...). Considering that the servo screen caught this, it seems unlikely it would have passed through the gascolator screen.

I wonder if the fuel filter at the last place you fueled is coming apart.

[cbarry]

It also could be upstream from the fuel nozzle that fueled your aircraft.  

[RobertGary1]

24 minutes ago, cbarry said:

It also could be upstream from the fuel nozzle that fueled your aircraft.  

But pass up the finger screen and through the collator and likely the “secret” filter at the electric pump?

[A64Pilot]

gascolator clean, but servo filter clogged? I’m thinking it came back from overhaul that way

[Mooney 217RN]

That looks like carpet fiber.  There shouldn’t be anything in your fuel system that produces fiber material like that except your fuel filter..  And nothing in a fuel dispensing system would have fiber in it spare filtration.  Somewhat strange.  

[mhrivnak]

30 minutes ago, RobertGary1 said:

But pass up the finger screen and through the collator and likely the “secret” filter at the electric pump?

This is a 1990 J without that filter. Just the gascolator screen and servo screen.

[carusoam]

Got a microscope?

Be on the look-out for the rest of the mouse’s parts…

See if the fibers are natural or synthetic… do they melt, or smell like burned hair when lit?

 

The amount of material in the pic… is a lot…

If that is coming from a degrading hose… there can’t be much more hose left….

 

Have you shared the pic with your primary fuel supplier?

Have you observed the rate of flow out of the fuel sep drain? (Might be slower than normal)

Check the tanks and their screen as well… (easy)

Check the fuel sep screen… (fine enough to collect fibers like this)

 

 

Lets see if @M20Doc has seen anything like this before… (fiber wad collected in fuel injector servo screen)

 

Doesn’t look normal or expected, in any way…

PP thoughts only, not a biologist or mechanic…

Best regards,

-a-

[Mooney 217RN]

1 hour ago, carusoam said:

 

If that is coming from a degrading hose… there can’t be much more hose left….

 

The heat sleeve on a fuel hose is outside of the steel braided rubber.  I lost a high pressure fuel line in flight, and I have that hose in my hangar.  I am intimately familiar with the construction of those hoses.  You'd need a pretty big hole in the steel braided rubber hose to pick up that amount of fiber.  The only way you'd get that is friction or heat.  Mine failed because my former shop clamped the hose abutting an exhaust stack, thinking it was an intake tube.

[GeeBee]

First look in the aircraft fuel tanks, pull some fuel and do a Millipore or membrane test. 

If it is positive, you need to look at the fuel tanks then the fuel supply. It is entirely possible a rag or other material got put into your tank at annual. Equally so it is possible the same contaminant could have got into the fuel supply while someone worked on the supply tank or truck. (I've had this happen, found a sweater floating in the fuel truck tank).

If your aircraft tank is clean, the you can look down stream, hoses, etc. If not you have to look backwards towards the supply, which means you got a big flush and cleaning to do. 

My guess is you're going to find something in the aircraft tanks. Just a matter how it got there.

[mhrivnak]

The gascolator is as clean as they get, so it don't think this could have come from upstream of it.

Here's a pic through a magnifying glass. It seems to mostly be brown fibers that are brittle, with a few longer colored fibers mixed in. I've found red, white, blue, black, and green.

[A64Pilot]

But how did it get past the gascolator screen?

[A64Pilot]

Pretty much had to either be in the line, or in the servo, neither makes sense.

Could it be some kind of spider nest?

[mhrivnak]

Just now, A64Pilot said:

But how did it get past the gascolator screen?

I think it has to be one of four things:

1. something deteriorating in the system past the gascolator. But as noted, nothing seems to fit this material.
2. it was inside the fuel pump that we just installed.
3. it was already in the screen when the servo came back from the overhaul shop.
4. while the fuel lines were open, something fell in or some small critter introduced this material. I did try to keep open lines covered, but I probably wasn't perfect about that.

They all seem unlikely, but I don't see any other options.

Just speculating: I could believe that the material is a bit of cardboard or similar that's been soaked and tossed around.

[EricJ]

1 minute ago, mhrivnak said:

I think it has to be one of four things:

1. something deteriorating in the system past the gascolator. But as noted, nothing seems to fit this material.
2. it was inside the fuel pump that we just installed.
3. it was already in the screen when the servo came back from the overhaul shop.
4. while the fuel lines were open, something fell in or some small critter introduced this material. I did try to keep open lines covered, but I probably wasn't perfect about that.

They all seem unlikely, but I don't see any other options.

Just speculating: I could believe that the material is a bit of cardboard or similar that's been soaked and tossed around.

There's not a lot of hose between the gascolator and the servo, so that should be relatively easy to check.   If that checks out and everything else checks as well I'd consider just continuing to run it and check the servo finger filter regularly until you're confident that the issue was temporary.

[mhrivnak]

I think we have a winner. This is a piece of cardboard box I pulled out of the trash, magnified the same way. It looks like the same stuff.

[carusoam]

Great pic of the box!  With its incriminating blue and red colors…
 

If it was a deteriorating hose… there would be plenty of rubber or other polymer bits to go with it…

The pic shows just fibers…

More likely to be a foreign object that came in with the new parts… or at the time the new parts got installed…

If there are fibers in the fuel pump…

Check the layout drawing of your fuel system…

This will help identify everything that is downstream from where you have noticed the fibers…

They typically won’t be able to swim upstream…

But they can miraculously do a good job of flowing downstream…

 

Also consider where your FF sensor is… if you have one…

If connected to the JPI… you can download lots of ops data… and see if the FF readings have been affected by fibers getting in there…

PP thoughts only, written before the latest pic got posted….

Best regards,

-a-

 

[Guest]

1 hour ago, mhrivnak said:

I think we have a winner. This is a piece of cardboard box I pulled out of the trash, magnified the same way. It looks like the same stuff.

Even if it’s the same material, how did it get into the servo finger screen?  Were there shipping caps on the servo fitting?

Clarence

[GeeBee]

You still don't know where the cardboard (if it is cardboard) entered the system. Are you really going to chance flying with possibly contaminated fuel? Unless you can be definitive on where it entered the system, you don't know where, how much more.

In the case of the errant sweater, it showed up on the fuel gauges. The screens showed clear, but the fuel gauges said, "contaminated fuel" and until we ran a Millipore test, the fibers could not be seen. Indeed they had made their way past the screens but we found some hanging from the nozzles.............

[RobertGary1]

10 hours ago, mhrivnak said:

This is a 1990 J without that filter. Just the gascolator screen and servo screen.

I would double check. A lot of planes added this filter by SB and it’s not noticed hence it’s called the “secret filter”. 

[Guest]

3 hours ago, mhrivnak said:

The gascolator is as clean as they get, so it don't think this could have come from upstream of it.

Here's a pic through a magnifying glass. It seems to mostly be brown fibers that are brittle, with a few longer colored fibers mixed in. I've found red, white, blue, black, and green.

I’d be sending some pictures to the overhauler. I’d be questioning their test bench contaminants.  If there is no evidence in your fuel gascolator, it’s doubtful it came from your plane.  
 

Clarence

[mhrivnak]

8 minutes ago, RobertGary1 said:

I would double check. A lot of planes added this filter by SB and it’s not noticed hence it’s called the “secret filter”. 

That's a good tip, though I replaced the boost pump about a year ago and still have pictures of the area to confirm there is no additional filter.

[Guest]

1 hour ago, mhrivnak said:

That's a good tip, though I replaced the boost pump about a year ago and still have pictures of the area to confirm there is no additional filter.

SB M20-222 doesn’t apply to your serial number.

Clarence

[PT20J]

If the gascolator screen is clean, the contamination has to be between the gascolator and the servo. I’d flush it well with the boost pump, put it back together and ground run it for a while and then check the servo finger screen again.