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Fuel Cap Rain Cover


Gary0747

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51 minutes ago, Gary0747 said:

... but I hate the water that collects on top and around the edges of the cap going into the tank when the cap is removed ...

I had the same concern until Clarence provided the obvious (in retrospect) solution.  Have a sheet of paper towel handy.  Blow around the ring.  Surprisingly, it gets about 95+% of the water out of the hollow.  Remove the cap and there'll be only a few drops of water remaining to towel up.

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I got the expensive orings on my caps and they do not leak either but I hate the water that collects on top and around the edges of the cap going into the tank when the cap is removed plus having the extra protection

I keep a small can of compressed air in the tool bag to blow out all the resting water. That along with the Blue o rings I don’t worry about the water.


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8 hours ago, Gary0747 said:

I got the expensive orings on my caps and they do not leak either but I hate the water that collects on top and around the edges of the cap going into the tank when the cap is removed plus having the extra protection

No worries.   I saw some post on FaceBook Mooney page about someone draining multiple cups of water out of his tanks.

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15 hours ago, xcrmckenna said:


I keep a small can of compressed air in the tool bag to blow out all the resting water. That along with the Blue o rings I don’t worry about the water.


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You know, I had that happen taking off one of the caps, where the cap slipped in my hand and the tablespoon of water sitting in the cap went into the tank.  After swearing for a bit, I sumped the tank with no water, then sumped it 5 minutes, jiggled the wing spar a little, and sumped 30 minutes later with no water.  I took off on the other tank and switched to the suspect tank, and never felt or saw a hiccup.  I've never caught any water while sumping before or since then either.

Where the heck does the water go?

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You know, I had that happen taking off one of the caps, where the cap slipped in my hand and the tablespoon of water sitting in the cap went into the tank.  After swearing for a bit, I sumped the tank with no water, then sumped it 5 minutes, jiggled the wing spar a little, and sumped 30 minutes later with no water.  I took off on the other tank and switched to the suspect tank, and never felt or saw a hiccup.  I've never caught any water while sumping before or since then either.
Where the heck does the water go?


Lol, I meant more with the combination of the blue o rings and compressed can of air I don’t worry about getting any water contamination. But that’s a good question. I am an expert now draining my fuel tanks for installing my CiES fuel senders and JPI 900 and calibration.

If you want, we could get those upgrades in your plane and find that lost bit of water....:)


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2 minutes ago, xcrmckenna said:

Lol, I meant more with the combination of the blue o rings and compressed can of air I don’t worry about getting any water contamination. But that’s a good question. I am an expert now draining my fuel tanks for installing my CiES fuel senders and JPI 900 and calibration.

If you want, we could get those upgrades in your plane and find that lost bit of water....:)

 

 

No thanks, I don't have upgraditis like you :D

A tablespoon of water in 30 gallons of avgas is something like 0.01%.  I'm guessing that amount of water is miscible/soluble in avgas.  I can't find any info on how much water can dissolve in avgas, though.

Edit: I found something, an EPA memo on water solubility in gasoline, which suggests 0.15 teaspoons per gallon, so about 4.5 teaspoons or 1.5 tablespoons.  So it is within reason to assume that most of the water you drop in from the fuel cap lid will dissolve in avgas given sufficient time.

"Since MTBE has much less affinity for water than does

ethanol, however, phase separation for MTBE/gasoline blends

occurs with only a small amount of water, as shown in Figure 2.

A blend of 85% gasoline and 15% MTBE can hold only 0.5 teaspoons

at 60 degrees F per gallon before the water will phase separate.

For comparison, one gallon of 100% gasoline can dissolve only

0.15 teaspoons water at the same temperature. These figures are

far below the 3.8 teaspoons which will cause phase separation in

the 90/10 ethanol blend."

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2 hours ago, jaylw314 said:

You know, I had that happen taking off one of the caps, where the cap slipped in my hand and the tablespoon of water sitting in the cap went into the tank.  After swearing for a bit, I sumped the tank with no water, then sumped it 5 minutes, jiggled the wing spar a little, and sumped 30 minutes later with no water.  I took off on the other tank and switched to the suspect tank, and never felt or saw a hiccup.  I've never caught any water while sumping before or since then either.

Where the heck does the water go?

Based on looking inside my tanks as they were being resealed, it is likely possible for a tablespoon of water to sit in the tank below the sump holes.  The intake screen is significantly higher so if it sumps clear it would not make it to the intake tube.

Pic from my '76F.

drain.jpg

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19 minutes ago, Two7Victor said:

Based on looking inside my tanks as they were being resealed, it is likely possible for a tablespoon of water to sit in the tank below the sump holes.  The intake screen is significantly higher so if it sumps clear it would not make it to the intake tube.

Pic from my '76F.

drain.jpg

That's a nice picture!  You shouldn't have told us you took it during a reseal, I would have been terribly impressed with your flexibility :D

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The Mooney airframe is not the only one with the same design of filler port and cap, Beech used it as well.  The Piper Comanche has the caps under a sealed door, the filler neck is raised above the tank adapter and the entire area has a drain.

Clarence

D684B19A-AE2C-45B6-8CBB-E8C697C65116.jpeg

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Change the four gaskets annually.  Adjust the caps to be properly tight.  Make sure caps are not cocked.  Sump your tanks.  This gadget is NOT necessary.  Compressed air.  Funny.  Just be a little careful when removing cap after outside.  MAAN-Much ado about nothing...

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On 10/1/2018 at 10:00 AM, MyNameIsNobody said:

Change the four gaskets annually.  Adjust the caps to be properly tight.  Make sure caps are not cocked.  Sump your tanks.  This gadget is NOT necessary.  Compressed air.  Funny.  Just be a little careful when removing cap after outside.  MAAN-Much ado about nothing...

Yea I’m getting the biggest chuckle from this thread. People are searching for a solution to a problem that doesn’t exist 

-Robert 

 

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Yea I’m getting the biggest chuckle from this thread. People are searching for a solution to a problem that doesn’t exist 
-Robert 
 

Lol, I’m sure there are people that have thought about problems you have had through your life. Each their own.


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