Fuel drains

[ArtVandelay]

So, my AP replaced a fuel drain on my J about a year ago, it started leaking again. It was from the valve itself, it wasn’t closing properly.

Fortunately I had one in my spare parts bag, and was able to replace it and it seems to have fixed the leak, I will need to fill the tank to be sure. I didn’t want to over tighten it.

A couple of observations:

1. It’s unlike a bolt, the fit is snug and I can’t unscrew it by hand, I thought this was odd. Same on reinstall.

2. The manufacturer my AP used is SAF-AIR, which supposedly can be rebuilt, as oppose to the old MDI versions. The problem is the SAF version has a spring that takes considerable effort to open with my sample cup, so much so that I thought it might break the plastic cup. I have to think maybe this is also why it failed so quickly.

3. My spare was a MDI version, much less effort to open the valve.

4. Seems SAF are everywhere, after my experience I like to avoid that brand.

 

Anyone else with SAF versions have the same issues?

[EricJ]

Yeah, the spring is hefty in the SAF units.   They both work, and usually when they're leaking from the valve it's because there's some sort of debris caught in the opening, and just jabbing it a lot to try to wash out the crap often fixes it.    Usually. 

The o-ring that seals against the bottom of the wing is part of what gives the resistance to removal and installation.   It is important to not overtorque it on installation since install torque is resisted mostly by the rivets that hold the nutplate in place, and they need to remain sealed or they'll become a leak source, too.  So if too much twist moves those rivets, they may start to leak.    It just needs to be snug so that the bottom o-ring seals sufficiently.

[PT20J]

MDI is out of business. Someone posted an alternate to the SAF-AIR which supposedly has a less stiff spring but I don’t remember the company name. 

[N201MKTurbo]

https://curtissuperiorvalve.com/tablet/index.htmlL

 

[RobertGary1]

I bet if you run it enough you’ll flush out whatever keeps it from closing 

[Fly Boomer]

On 5/13/2023 at 1:18 PM, PT20J said:

MDI is out of business. Someone posted an alternate to the SAF-AIR which supposedly has a less stiff spring but I don’t remember the company name. 

Here is a cross-reference to Saf-Air

http://curtissuperiorvalve.com/assets/cutisvalvesaf-aircrossrefchart_v8.pdf

[ArtVandelay]

I bet if you run it enough you’ll flush out whatever keeps it from closing 

I tried many times with no luck, after removing it I was able to clean some sticky debris using a toothpick.

[Fly Boomer]

4 minutes ago, ArtVandelay said:

I tried many times with no luck, after removing it I was able to clean some sticky debris using a toothpick.

Goop coming out of the tank?

[ArtVandelay]

Goop coming out of the tank?

Don’t know, small piece about the size of a grain of sand. Could be anything, tree debris, insect, who knows.

[GeeBee]

It is important when you drain, to push up fully to open the valve wide open (make sure you feel the stop), and drain a lot, I usually drain at least 12 oz. This give the drain a good flush and insures a clean tank. If you look at M20Doc's post you can see the contaminants have to make it over the fitting to get into the flow. The only way to do that is to set up a strong internal stream  by draining more than a few ounces.  Most people drain with those little tubes or small cups. I used to have a PA-18 with forward facing vents on the fuel caps (due to an STC to remove the header tank) that were bug eaters and unless you really flushed the valve with a big cup, they would get debris under them and a PIA to clean out later. If you're getting "booggers" continuously, it is probably end stage failure of the tank sealant.  Finally I don't put the sump fuel back in the tank. It either goes in the lawn mower or gets dumped. The environmentalists can come an arrest me if they want. 

[ArtVandelay]

It is important when you drain, to push up fully to open the valve wide open (make sure you feel the stop), and drain a lot, I usually drain at least 12 oz. This give the drain a good flush and insures a clean tank. If you look at M20Doc's post you can see the contaminants have to make it over the fitting to get into the flow. The only way to do that is to set up a strong internal stream  by draining more than a few ounces.  Most people drain with those little tubes or small cups. I used to have a PA-18 with forward facing vents on the fuel caps (due to an STC to remove the header tank) that were bug eaters and unless you really flushed the valve with a big cup, they would get debris under them and a PIA to clean out later. If you're getting "booggers" continuously, it is probably end stage failure of the tank sealant.  Finally I don't put the sump fuel back in the tank. It either goes in the lawn mower or gets dumped. The environmentalists can come an arrest me if they want. 

As mentioned the SAF spring is stiff, making it difficult to push the drain up given the low wing with an outreach arm.
I use a gats jar, so have no problem putting strained fuel back into the tank.
Your dumping +24 oz of leaded fuel? I prefer not to give environmentalists any more reasons to trying to close down airports.

[GeeBee]

1 hour ago, ArtVandelay said:

As mentioned the SAF spring is stiff, making it difficult to push the drain up given the low wing with an outreach arm.
I use a gats jar, so have no problem putting strained fuel back into the tank.
Your dumping +24 oz of leaded fuel? I prefer not to give environmentalists any more reasons to trying to close down airports.

What they don't know they don't know. Trust me, they will target noise before sump fuel. As for the spring, I put down a beach towel or in the hangar use a creeper and I get right underneath and push straight up and hold.