I'll dig in the logs and see if I can find any info on it. As far as I know, there is the filter in the tanks, the gascolator, then this one. I did have the electric pump overhauled last year.

Thanks for the following up!! Good call Trent.
I check them every annual on these engines and injected lycomings. The bendix injection filter on a lycoming will just bypass. You will not loose flow but will usually start plugging injectors once you bypass that filter.
You might consider cleaning the injectors, flushing your fuel lines and clean out the flow divider. Probably over kill tho.

There are always hairs in the screen.
It has to be from installing the fuel cells rubbing the hair off of the mechanics arm!
I always wind up bruised trying to snap the cell in.

Then the hair finds its way through the finger screen and through the gascolator screen and winds up there.


Glad you found the problem

When Changes happen "The last thing touched (changed) is first thing to look at" -BR

Great thread.

A couple of thoughts.

First my compliments for paying attention to your instrumentation and acting accordingly.

Next it seems crazy to feed an airplane engine through such a little strainer, but I guess it works 99.9% of the time...

I wonder what would have happened if it got just a little more clogged in flight?

Nice on line diagnostic work, gentlemen.

That tiny fine filter is really more of a "last chance", in theory.
If that doesn't catch any fine gunk them the injector nozzles themselves would block.

Upstream of that tiny filter, a typical injected fuel system might have:
2 low-point drains at the tanks
4 strainers at the fuel tanks outlets (very course)
1 low-point drain at gascolator
1 gascolator with integral filter (coarse)
1 full-flow filter (very fine)

So there are a whole bunch of chances to catch stuff before that last tiny filter. But if you don't have the full flow filter, fine particles which get past the tank drains and gascolator (typically particles which are very small and float...) have nowhere else to go.

I do have the full flow filter, and have never found anything which had made it as far as the "last chance" filter in the fuel servo.

That tiny fine filter is really more of a "last chance", in theory.

Totally understood.

Also a last chance for a 'clot' (medical thinking here...) to block fuel flow and bring down a plane.

Funny how that material congealed there.

Our hangar neighbor was tragically lost due to blocked fuel line. It was an IO-540 (injected).

http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=62DN

http://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief.aspx?ev_id=20140531X15032&key=1

...The pilot, who was also the builder of the experimental kit airplane, departed for a cross-country flight from his home airport. The passenger reported that, following a normal departure, the airplane continued the takeoff climb through some cloud wisps and ascended above a lower cloud cover with an overcast layer above. Suddenly, the engine experienced a total loss of power. The pilot maneuvered the airplane toward the closest airport, but, when he realized that the airplane would not be able to glide to the airport, he attempted to make an off-airport landing. The airplane stalled and then collided with terrain in an open area of a paper mill. Ground scar analysis and wreckage fragmentation revealed that the airplane descended in a steep, near-vertical, nose-down, left-wing-down attitude before it impacted terrain.The pilot installed a fuel flow transducer about 2 to 3 weeks before the accident and used heavy applications of room temperature vulcanization (RTV) silicone to seal the fuel lines. A friend of the pilot, who was also a mechanic, reported that he had observed the pilot about a year earlier using heavy applications of RTV silicone to seal parts during a condition inspection and that he had mentioned to the pilot that this was an improper practice. A bead of RTV silicone was found in the fuel line, and it is likely that it blocked the inlet of the transducer and starved the engine of fuel. Additionally, subsequent to the loss of engine power, the pilot failed to maintain sufficient airspeed while maneuvering to locate a suitable off-airport landing site and flew the airplane beyond its critical angle-of-attack, which resulted in a stall and loss of airplane control.

Wow , that's kind of a lot of junk you got there . I have always been very paranoid about clogged fuel screens and any other things that will cause fuel to not make it to the engine. Every fuel screen should definitely be inspected and cleaned on the the 100hr. Any idea what that gunk might be .?Maybe drain the tanks and flush so you are certain you don't have any more of that crap on the bottom of your bladders? Interesting that you didn't get a plugged injector first . Well the screen did it's job I guess .Glad you got it sorted out . Did any of the other screens have stuff in them ?

I had an intermittent engine failure (aka "crapping out") in my old C170 once years ago. Limped back to the airport from about 20 miles away, with the engine cutting in and out, and lost 1000' of altitude in the process. Landed safely, taxi'd back to the hangar just fine. Tore into it, turns out the fuel inlet screen at the carb was clogged with some weird fiberous stuff. It looked like what you'd get if you dropped a red shop rag in the fuel tank and just let it dissolve over many years. (maybe that's what happened??). This stuff made it past the screens (if any) at the fuel tank outlet(s), past the gascolator, and past the fine screen inside the engine-driven fuel pump that was part of the 1948 170 fuel system. I'd owned the airplane for close to 10 years & annualled it with three different IA's, none of whom ever checked that screen or told me to. The fuel lines at the carb were configured in such a way (hard lines, check valve, a couple of tees) that it was a PITA to pull the screen, so I guess nobody ever wanted to mess with it. Checking the carb inlet screen at every annual became part of the ritual after that...even though I never again found anything in them, on that plane or the two I've had since.

I'm thinking something similar happened here. The way it was safety wired, there was no way it was done without big pieces being off the plane...like the air box and everything else above it. I'm thinking that it was never checked since because no one wanted to bother with it. There was no way to safety wire it to the same place. It is now wired to a more reasonable spot. I've not pulled the gascolator yet. I've since put about 10 on the plane and pulled the screen again after a few hours with no more sign of junk.