Thorp Air Command - T18.net

There is always a lot of grit found in my oil filter when I send it in for oil analysis. I cant find anywhere that I think unfiltered air is getting into the system. Only other thing is I would think is that I would need to try a different air filter. Any other suggestions as to how to lower the amount of grit being found?

Is it solid "grit" like pieces of sand or is it black granules that can be crushed when put between your fingers ? If it is black and can be crushed it may just be carbon deposits from combustion . Exactly what are the oil guys saying it is ? I used the disposable foam infused with some type of oil from ACS for my air filter . What filter are you using now ?

RB

When I cut my own open, it doesn't look black like carbon. I do notice some grit (like sand or dirt), but it doesn't worry me when looking at it. When I send the filter into Avlab for analysis, they always come back with "Major Grit" found. I use a Wix brand filter. I guess it would be worth a try to use another brand. Im just wondering if Im missing something obvious thats allowing the dirt/grit into the system which is being caught by my filter.

Hey Ryan,

Are you talking about sending your air filter into a lab for analysis (shown in the picture), or your oil filter. And surely you're not sending the whole oil filter in - just an oil sample, right? Do you fly from a dirt strip?

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

I thought you were talking oil filter and don't call me Surely . If it is the air filter is it possible that it is not sealing correctly in the housing ?

RB

Carb heat air leak?

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Bob Highley
N711SH
SN 835
KLAL

Proper fit of the air filter in the housing was the first thing that came to my mind when I saw what is being used. I have seen that style of filter siliconed top and bottom because of improper fit (loose). Carb heat boxes are rarely tight and provide unfiltered air if on.

I would think the analysis shop could tell what the "grit" is. Grit could be anything from carbon to sandblasting media or even metal filings.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Sorry for the confusion. I am talking about the results of my oil filter analysis. I have called Avlab about what "grit" means, and although I cant recall exactly what they said now, I came away with the understanding that it was basically dirt. I was thinking that the only way grit could be getting in was around a poor fitting air filter (and now I'll check the carb heat box too). I only fly off paved runways.

I just wanted to bounce it off everyone in case I was missing something obvious.

well, I called Avlab today to reinforce my understanding of what "major grit" was and what they considered "grit"......and I am glad I did. Apparently, when they say "major grit" was found in my oil filter, that is a good thing, and it means my filter is doing its job really well. Grit is defined as anything that is caught by the filter. I hope that may help somebody understand their filter analysis in the future.

I am glad to hear you didn't have a problem that needed fixing.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Ryan : Did you find my lucky penny in that filter ?

RB

You may want to think about the drain tube that you use the get the oil out, if you use one? Those tubes get dumped on a bench after use and collect dirt which in turn comes out in the sample that you send off.
I just had the same problem with my Debonair and the tube I used had not been used for a while and was the culprit. Wash the tube out with gas before use was my solution.
Speedbird 1.

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N872DD
200hp Lycoming

Ryan
The filter in your picture, is that the one called out in the original Thorp drawings? I'm having a great deal of trouble trying to find one for my T18. I gather its a WIX, can you give me a part number.
Cheers
Tony
ZK-VMS
T18C

I don't know if its the one called out in the original drawings, but it fits my filter box like a glove. Its WIX part # 42091. I have just switched to using a K&N Filter that is a cross referenced fit to the WIX 42091 in hopes of reducing the amount of grit found in my oil filter samples.

Thanks Ryan
Dimensions look familiar, all I need to do now is find a local supplier. WIX is not common in NZ!
Cheers
Tony