Fuel tank particals

[leighton]

Has anyone seen small white lint like particals in the main fuel screen, also see these particals on first fuel sample of the day from the left tank,second fuel sampling is clear. Concerned some of these particals could get thru screen and block main jet. Tanks were removed and inspected three years ago, no problems found. Bob 3133B.

[cessna170bdriver]

Sounds like paper or rag debris? Did anyone wipe off the fuel tank neck for any reason? I've never seen anything like that in mine, but I did find a wasp INSIDE the gascolator once.

[leighton]

Thanks Miles but no rags used near the cap, remains a mystery.

[cessna170bdriver]

I'd have to have a look around inside the gas tank with an inspection mirror just for peace of mind.

[Bruce Fenstermacher]

I've seen particles from time to time as you describe in a fuel sample but I can't remember if it was out of an airplane or lawn mower. Likely an airplane since the 100LL is clear enough to see such things. I can not recall ever finding anything in a gascolator that i'd tie to such particles.

I can't recall doing anything about it other than ensuring there was nothing obvious in the tank that shouldn't be. I may have flushed the fuel from the airplane and run it in my lawn mower (and that is how I saw may have seen the particles in my mower ).

[BeeMan]

I’ve posted this before but this thread is probably a good spot to relate the story again. Not long after buying my 170B I experienced a partial power loss that initially manifested as a slight tic in the indicated RPM. Pulling carb heat initially seemed to help. Problem gradually worsened until I was losing 100 to 200 rpm on about 1 to 2 second cycle. I made it back to home field and started to troubleshoot. Fuel flow to gascolator was fine as was fuel flow after pulling fuel line off at carb. At that stage we pulled the finger screen out of the carb and found it packed full of very fine fibers that were restricting fuel flow. Once I knew what to look for I was able to see a few fibers swirling in a fuel sample collected at the tank sump or from the gascolator but only when bright sun light was shining on the sample and it was held against a dark background. We disconnected and purged fuel lines, flushed tanks, etc. and came up with a clump of fibers from the left tank. My A&P was not able to identify the fibers and we were never able to establish where they came from except for something (rag, tape, etc?) lost in the tank by a prior owner/operator/mechanic. I believe the fibers were light enough to remain entrained in the fuel flowing through the gascolator while flying and small enough to fit through the gascolator screen if oriented just right. I also believe that this transport of fibers had been happening for a looong time and the finger screen in the carb had not been checked for at least several annual inspections. Lesson to be learned – look carefully for fibers entrained in swirling fuel when checking sumps and IF you see them, pull the finger screen from the carb and make sure it isn’t collecting fibers like mine was.

[bsdunek]

Or, could have come from refueling. Last Fall, I had two problems with a metal shaving in the left drain valve. Each time, it was caught in the seal and the valve would leak. The tanks have never been removed since installed at the factory, so if these shavings were from the factory, they certainly would have shown up many years ago. I have refueled the plane myself for at least the last 12 years, and I know I didn't do anything to allow them in. My conclusion is, they came from refueling - how, I don't know.
I do carry an extra drain valve in my tool kit just in case it shows up away from home.

[Bruce Fenstermacher]

Beeman jogged my memory. I had the exact same thing that Beeman had happen to me. On my very first flight of my first and new to me 170, I was loitering around the sky at a low throttle setting pretending I was flying my Cub. After about 45 minutes this I advance the throttle but the engine just quit. Quickly pulled the throttle back to where it was and the engine resumed the RPM it was at. I carefully advanced the throttle again and again the engine nearly quit. Pissed me off really. I did not have any fear despite being in a new plane in the second day of ownership with an engine that didn't want to run. After a few moments of trouble shooting the thought came to me I'd be better on the ground trouble shooting than at 1500ft and so I adjusted the throttle for max rpm of about 2100 and limped 10 miles back to the airport.

Trouble shooting found nothing wrong with fuel delivery to and through the gascolator. But the carb finger filter was another story. When I pulled that it was packed full of what I thought was a cigarette filter. It was a tightly packed fine yellow whitish fiber. It was so perfect I actually took it to an IA and asked him if he;d ever seen a filter in the finger filter screen in a carb. Of cours the answer was no.

We inspected the inside of the tanks best we could with a light and mirror and flushed the fuel. That is probably when I remember the fine almost crystal like fibers in fuel.

With tanks, fuel lines, gascolator and carb flushed I flew above the airport for about an hour and pulled the finger filter to find it clean. And it was clean again in another two hours. Have never found anything since in a finger filter.

[leighton]

Thanks all for the responses, material in the fuel still remains a mystery. Decided to clean the gas collator screen and drain the culprit left tank, more white particals found. In the process found my fuel valve would not shut down fuel flow competely in off position so selected left tank and drained. Right tank did shut off correctly. So I am wondering if fuel flow is normal in the both tank position if I need to be concerned about failure of the valve, Read G. Horns artical on the valve and would prefer to wait till annual to replace.

[Bruce Fenstermacher]

Your airplane, a 1952 Cessna 170B C/N 25375, has the later style fuel selector. Each side is sealed in the off position by it's own o- ring. Sounds like one is failing to make a seal and the other is not. The only thing more that could fail is the control shaft o-ring seal and the valve start leaking out the top.

I would not be concerned about fuel flow interruption unless of course you want to turn it off.

[leighton]

Thank you Bruce, I will sleep better tonight. By the way, what you describe (white fine crystal like) is exactly what I have. I can't see anything obvious in the tank so will flush one more time and watch the screen. Did notice I still have cork floats but gauges are reading OK.