common sources of debris in fuel tank?

[Unregistered]

Before I preflighted this morning, I found some old debris in the gats jar. I hit it with a magnet and saw some fine slivers of silvery metal jumping around. Cleaned out the gats jar, sumped, and found another piece of crud, like a big grain of sand. Seemed to be isolated to the right tank. Plane just got out of annual recently. No obvious metal shavings or dirt or degraded rubber at the filler cap. Is the source of debris likely to be external, or can the tank itself be shedding junk? The aircraft in question is a 72 Cherokee in a partnership.

 

[Dan Thomas]

Is the fuel cap chafing the underside of the filler neck with its spring tabs? Has someone been filling it from a jerry can and using a dirty funnel? Did someone fuel it at night and leave the cap off long enough to let some moth get in there? They are attracted by the lights at the pump and love the smell of gasoline and end up in there, where they break up into curious little bits that often foul the drain valve and make it leak or maybe plug it altogether.

Dan

 

[kyleb]

Metal shavings (rubbings) from the fuel nozzle or its swivel assembly?

 

[0luke1]

1972 was a long time ago.

I had to declare an emergency after the left wing stopped feeding fuel and what I thought was a fuel imbalance ended up being a lot of unusable fuel.

The cause was a ball of tar that clogged the check valve. The mechanic said "that could have been in there for 20 years."

 

[ElPaso Pilot]

Uncommon source of debris in fuel tank?

Frog carcasses.

How do frogs get into a Mooney fuel tank? ​

This photo is courtesy of Greg and Andrew Manzie who posed the question: how do frogs get into a Mooney fuel tank? Top marks to Brian Dunstan who concluded is that they crawl into a fuel nozzle when it is cool and free of fuel and then get pumped into the fuel tank by an unsuspecting pilot. ​

 

[JHW]

metal shavings are probably from the pump on the back of the fuel truck eating itself

 

[Fearless Tower]

metal shavings are probably from the pump on the back of the fuel truck eating itself

Is buy that. He did say that they were ferrous (attracted to the magnet), so that should rule out cap/filler neck/nozzle interaction.

 

[MAKG1]

Is buy that. He did say that they were ferrous (attracted to the magnet), so that should rule out cap/filler neck/nozzle interaction.

I thought the filler neck was steel -- at least the small part in contact with the cap. Maybe I'm mistaken, but aluminum wouldn't last long.

But, frankly, I'd be much more concerned about the fuel delivery chain. There could be some fuel pump somewhere eating itself up.

 

[Dan Thomas]

I thought the filler neck was steel -- at least the small part in contact with the cap. Maybe I'm mistaken, but aluminum wouldn't last long.

But, frankly, I'd be much more concerned about the fuel delivery chain. There could be some fuel pump somewhere eating itself up.

The tank's filler neck is indeed steel. And so is the tab on the cap that engages with it.

Dan

 

[Fearless Tower]

The tank's filler neck is indeed steel. And so is the tab on the cap that engages with it.

Dan

What kind of steel? Is that universally so, or just certain AC types.

 

[Dan Thomas]

What kind of steel? Is that universally so, or just certain AC types.

Aluminum would gall far too easily, so steel is used. I have no idea what grade of steel it is, but the filler neck would be some ductile stuff to allow forming so it's probably a low-carbon steel, and some might be stainless steel. The tab is very tough stuff, probably a spring steel such as 6150.

Dan

 

[Jimmy cooper]

The tank's filler neck is indeed steel. And so is the tab on the cap that engages with it.

Dan

I agree although all of this is pure speculation. Where do you get gas usually? Some gas tanks at smaller airports are ancient. Probably lots of condensation and rust inside supposedly stopped by a filter. I don't think much attention is paid to gas tanks at annual other than to see if the quick drains work. It's an older airplane and who knows how something could have gotten inside. Possibilities are endless.