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ANDAIR fuel filter question

simatos

Well Known Member
I am servicing my Andair fuel filter which unscrews exposing the filter element.
The unit has an "O" ring to seal once reassembled. Im wondering if it would be necessary to use grease or some other material on the "O" ring to ensure the seal or should it work dry?? Look forward to any comments from anyone who has been down this road, Cheers Gary
 
I always apply a tiny amount of Fuel Lube to the o-ring and massage it around. I think it makes it easier to the bowl get on/off and may protect the o-ring from the gasoline as well as making a better seal. I have one andair gascolator in each wing root where there?s not a lot of room to get a grip.

Bevan
 
After my last annual, this o-ring ended up broken and a fuel leak resulted. It had been lubricated with fuel-lube. Fuel-lube is very thick and that may have caused the o-ring not to seat properly. My AME recommended using ordinary engine oil.
 
The lube doesn't help the sealing directly, it's just there to make sure things slide back into place correctly. A drop of engine oil is always my go to for o rings.
 
Andair says...

This is from Andair:

Undo the safety wire, unscrew the fitting then unscrew the safety wire end from the filter case. Blow the exposed filter out on an airline and swill it in clean fuel to remove any contaminants on the outside. Do not allow debris to get on the inside of the filter. Reassemble using grease or petroleum jelly. Safety wire as it was.
 
After my last annual, this o-ring ended up broken and a fuel leak resulted. It had been lubricated with fuel-lube. Fuel-lube is very thick and that may have caused the o-ring not to seat properly. My AME recommended using ordinary engine oil.

The lube doesn't help the sealing directly, it's just there to make sure things slide back into place correctly. A drop of engine oil is always my go to for o rings.

Oil works but a better choice is Dow Corning #4 (commonly refered to as DC4)
It is a silicone grease.
Any silicone grease intended for o-ring seals would be a good choice.
 
"Undo the safety wire, unscrew the fitting then unscrew the safety wire end from the filter case. Blow the exposed filter out on an airline and swill it in clean fuel to remove any contaminants on the outside. Do not allow debris to get on the inside of the filter. Reassemble using grease or petroleum jelly. Safety wire as it was."

It's amazing what you can learn from reading the available product technical data.
 
The O-Ring sometimes swell a tiny bit, so after you took it of (for greasing it), you will have a hard time to put it back. The chance of cutting the O-Ring during the re-assembly, is high. Had is once, since then, I spend the money and replace the O-Ring, if I open the filter.
 
Still looking for a USA source for Andair FX375 Filter O-rings

I sent the following email to Andair:

Do you know a source for spare O-rings for FX375 Filters in the United States? I thought Aircraft Spruce would have them since they handle your products. Also, would you tell me the size and material and what you recommend regarding lubricant when installing the replacement O-ring.

Here is their response:

"It’s an 11 x 2 Viton 75 O-ring. We can send one out to you if you are unable to locate one. You can use multipurpose grease."

I ordered and received the O ring from Andair. The O ring is actually 30 X 1.5 Viton 75. The inner diameter is 30mm, the outer diameter is 33mm and the thickness is 1.5mm. I bought 2 from Andair and had them send them the most inexpensive way (sent an email instead of ordering from their website). The total price was $10.48 delivered. I also bought 10 from McMaster-Carr:

https://www.mcmaster.com/9263K597

The delivered price for 10 from McMaster-Carr was $18.17. The shipping from them was $7.79 and was in just a few days via UPS. Not sure if they have a cheaper shipping method.


I am still looking for a source in the USA. If anyone knows where to purchase them and a part number I would be grateful.

So a USA source is McMaster-Carr or you can hit me up for one for free as I have a few extras.
 
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I could not find the dimensions of the Andair filter o-ring before servicing during my condition inspection, so ordered 2 spares from Andair. They shipped pretty quickly. Note: I ordered the o-rings by telephone. It would be good to find a source in the U.S.

Edit: McMaster Carr seems to have the correct orings, if your dimensions are correct. Seems too thick, though.
https://www.mcmaster.com/1295N225/
 
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Correct size for O ring from McMaster-Carr

I could not find the dimensions of the Andair filter o-ring before servicing during my condition inspection, so ordered 2 spares from Andair. They shipped pretty quickly. Note: I ordered the o-rings by telephone. It would be good to find a source in the U.S.

Edit: McMaster Carr seems to have the correct orings, if your dimensions are correct. Seems too thick, though.
https://www.mcmaster.com/1295N225/

I ordered from Andair too and then ordered from MaMaster-Carr. You are right the size that Andair mentioned in their email was incorrect. The correct size is 1.5mm X 30mm inner diameter, 33mm outer diameter. Here is the correct link at McMaster-Carr:

https://www.mcmaster.com/9263K597/
 
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