Tiny flakes in fuel from outboard sender gasket failure?

[toto]

At annual, the inspector noticed that there is a small amount of blue staining inside the access panel where the left outboard fuel sender lives. He thinks that the gasket is on its way out, and wants to replace it sometime (not urgently).

I’m seeing these teeny tiny flakes in the fuel from that tank, only when the plane has been sitting for a week or more. The photo below shows several flakes when it sat for two weeks - normally it’s a single flake (or clean). 

Just wanted the hive mind for a sanity check. Does this look like debris from a failing fuel sender gasket?

[EricJ]

Could be, or could be any other kind of debris, too.    When I first bought my airplane I'd regularly get little bits of debris like that in the fuel samples, and just monitored it to see if it got worse.   After a couple of years it just stopped and now I rarely see anything but fuel in the samples.   I've no idea what I was seeing, but since it stopped a long time ago I don't worry about it.   It does mean you should keep a little closer eye on your fuel filters as long as it is occurring.

You can take some mineral spirits or acetone and clean the stray dye out around the sender so that if it is leaking, you'll see the new stains.   Otherwise it can be hard to tell how old the stains are and whether it's from old leak or a current one.

[PT20J]

I had the same experience as Eric. I finally tracked the debris down to paint on the wing around the fuel caps chipping off and falling into the tank. 

Check that it’s not leaking from the sender screws. I’ve had a couple of those seep. You can remove them one at a time and coat the threads with EZ Turn or non-hardening Permatex  and retorque them gently (spec. is 20-25 in-lbs.)

[47U]

12 hours ago, toto said:

Does this look like debris from a failing fuel sender gasket?

What color is it?  How long since your tanks were resealed?  Could the top coat be deteriorating (maybe, reddish in color)?

[toto]

21 hours ago, 47U said:

What color is it?  How long since your tanks were resealed?  Could the top coat be deteriorating (maybe, reddish in color)?

As far as I can tell, they’re black - I haven’t seen any reddish color flakes. Tanks have never been resealed, but I’ve never had an issue with leaks. 

[PT20J]

1 hour ago, toto said:

As far as I can tell, they’re black - I haven’t seen any reddish color flakes. Tanks have never been resealed, but I’ve never had an issue with leaks. 

I would run a tank dry, let it sit for a day and then remove the sump drain and drain out all the unuseable fuel which will get the tank as clean as you can get it without flushing it. Then you can see if it comes back.