Beware fuel system icing - it happened to me...

[aviatoreb]

1 hour ago, Will.iam said:

One per side? I guess I’m missing something in my math. One bottle 16oz one gallon 128oz so one bottle only treats 12.5 gallons at 1% so wouldn’t you need at least 2 bottles + per wing? I hold 37.8 in one wing so i need at least 3 bottles for 1%. And my K poh says up to 3% so that would be 9 bottles. So one case wouldn’t even do a full fill up for me. This is getting expensive. 

Its ok - Im often adding half a tank to a half filled tank.  So it comes out in the wash.  Sometimes I have probably a tad bit low.  Sometimes I am likely a bit more than 1% but its ok because 3% is allowed.  I am aware of the math you described and I would add 2 to an empty tank.  I've also done 3 - 1.5 per side to roughly 1/3 full tanks.  Don't bug that I have LR.  Hitting 1% isn't a magic number like it does nothing at 0.7 or 0.8% - well at least I'm doing something.  Anyway how much IPA is needed in practice would depend on how much water really is in the fuel.  I guess I am hoping it is pretty low.  But some IPA in case it is not zero.

Edited January 6, 2022 by aviatoreb

[aviatoreb]

2 hours ago, Fly Boomer said:

Wonder what the other 1% is in those 99% bottles?

Cool whip.

So yeah it's water.  And for even more money there is 99.5% and 99.9% easily available.  (and even greater purity for even greater cost).  99% seems to me to be a sweet  spot of quite good/good enough, and decent price.  But once the bottle is open, it immediately wants to start attracting water out of the air.  Which is why I said earlier don't get a gallon jug and draw a little bit of a time out of it all winter - because by the end of that winter that gallon jug will be like 91% IPA.  Better to fresh open these little bottles immediately upon use.

[kortopates]

One per side? I guess I’m missing something in my math. One bottle 16oz one gallon 128oz so one bottle only treats 12.5 gallons at 1% so wouldn’t you need at least 2 bottles + per wing? I hold 37.8 in one wing so i need at least 3 bottles for 1%. And my K poh says up to 3% so that would be 9 bottles. So one case wouldn’t even do a full fill up for me. This is getting expensive. 

you don’t want anywhere near the maximum concentration - that is a maximum not a recommendation or minimum. All that you really need is enough to absorb any free water in the fuel system and no more.

But guaranteed that using 3% will cause premature failure of fuel system seals.

A little goes a long ways!

I see several of these every winter through Savvy. Never is the source of the moisture really known.

20+ years flying high into ski areas and I’ve never experienced this myself. And i am anal about keeping moisture out of my tanks with pristine o-rings on caps.


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[aviatoreb]

1 hour ago, kortopates said:

you don’t want anywhere near the maximum concentration - that is a maximum not a recommendation or minimum. All that you really need is enough to absorb any free water in the fuel system and no more.

But guaranteed that using 3% will cause premature failure of fuel system seals.

A little goes a long ways!

I see several of these every winter through Savvy. Never is the source of the moisture really known.

20+ years flying high into ski areas and I’ve never experienced this myself. And i am anal about keeping moisture out of my tanks with pristine o-rings on caps.


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Yes- the o-rings AD- me too.  But I always presumed somehow water got into the fuel by other means even besides leaking in through the caps.

I am curious - since you do see several a year through Saavy - is that enough that you do IPA in your own personal operation?

[kortopates]

I am curious - since you do see several a year through Saavy - is that enough that you do IPA in your own personal operation?

No, i’ve never seen a drop of water in my fuel. For a number of years I carried some IPA around in the winter ready to use if I found any water or experienced any hiccups - but i never did.

Back in the old days before airport security I knew a guy that returned to his airplane at a very small open field to find that a bunch of sugar had been poured into his tank. Thankfully he found this out before taking off only because he never failed to sump. It made me believer in always sumping too.
Now i never fail to sump regardless of taking on gas when the plane has been outside. Plus if the wing is contaminated with water or snow, i dry out the top of the cap where water collects with a paper towel before opening it.

Is everyone aware Mooney changed their pre-flight sumping guidance? Older POH’s started with sumping the gascolator first when starting the pre-flight from the cabin. In the more modern POH’s this changed to sumping the wings first and the gascolator last. The rational is that if there is water in a wing, you don’t want to allow it to get out of the tank into the fuel line by draining the gascolator.

Lastly be careful if you do find water in the fuel. More than one Mooney has come down after a pilot sumped and sumped till they thought they had it all out only to depart lose the engine because there was still trapped water.

sorry to digress from frozen moisture in the fuel


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[Ragsf15e]

On 1/4/2022 at 3:14 PM, PT20J said:

The drain only empties the sediment bowl which collects liquid water and particulates. During operation, fuel from the tanks fills the bowl and exits the top through a filter screen which is what collected the ice crystals. So, there is no flushing action through the screen by opening the drain.

Skip

Wait, is there a filter just after the gascolater?  I thought that was only if you had the plastic vane dukes electric fuel pump on an IO-360? I am now curious because I’m about to go through the fuel system on my annual and have planned to take apart the gascolater and the servo fuel screen but I was unaware of any other.  If what you’re referring to is only on continental engines, sorry for the digression…

[PT20J]

2 minutes ago, Ragsf15e said:

Wait, is there a filter just after the gascolater?  I thought that was only if you had the plastic vane dukes electric fuel pump on an IO-360? I am now curious because I’m about to go through the fuel system on my annual and have planned to take apart the gascolater and the servo fuel screen but I was unaware of any other.  If what you’re referring to is only on continental engines, sorry for the digression…

The inline filter is only for the Dukes boost pump. The screen I referred to is the one within the gascolator itself.

[0TreeLemur]

8 hours ago, kortopates said:

Lastly be careful if you do find water in the fuel. More than one Mooney has come down after a pilot sumped and sumped till they thought they had it all out only to depart lose the engine because there was still trapped water.

On my first XC after earning my IR in 2019 I got diverted to Bartlesville due to a line of convection from TX to WI.  I pi$$ed rain that night and I stayed in a crappy hotel.  The next morning during preflight I noticed pooled water on the right gas cap and none on the left cap so I was suspicious.  A line guy didn't put the gas cap back on correctly after refueling before the heavy rain.   I pulled four full sample cups of pure water out, then six or seven more with decreasing amounts of water from the left tank.   Still on alert I didn't think I'd get any water out of the right tank, but surprisingly pulled five or six sample cups of water out of that tank too!   Luckily I got it all and did not lose power on departure.  What I could I have done differently?   I did sump the tanks before draining the gascolator (I think).

[kortopates]

You did good, the only question is whether it’s enough.
Firstly, make sure you’re not just using one of those 1 ounce sump containers with the metal tip in the center. You really need to use at least a 16 oz Gatts Jar to get large samples.
Additionally you can add some IPA to absorb any remaining free water.
Also wait 20-30 minutes after you think you have it all and sump some more to verify.
If you do see more, then in an abundance of caution you can get a shop on the field (or sometimes even an FBO) to de-fuel your tanks to be really sure.
One of the problems is that water can get trapped behind a rib.

Just be aware more than one pilot supposedly did exactly as described by sumping till they only saw clean fuel, then took off believing they had it all out, only to loose their engine from water contamination.


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[EricJ]

Another Mooney trick is to vigorously shake each wing tip up and down for a while to encourage any water hiding behind ribs/drains to migrate down to the sump.   This helped a lot in my case when I was having chronic water problems after the previous IA left it out in a storm with rotting cap gaskets (long, frustrating story).

 

[carusoam]

great details Spam!

By chance… got a pic of the paste on the screen?

That would be a good one for every winter flying magazine article…
 

Always good to know all the sources of water…  some comes in with the fuel, fully dissolved…

Warm fuel carries more water than cold fuel…  think about getting fuel in a warm environment/time… then traveling to a much colder environment/time…

Turbo planes can visit some of the coldest environs… so they are at higher risk of experiencing ice crystals falling out of solution…

If the turbo engine dies because of the instability caused by a partial fuel blockage… it can be extra challenging to get it to restart at altitude…  (be aware of the turbo restart procedure… and it’s critical altitude to get a restart without the turbo spinning)

 

 

And where it can hide…

Once rain water enters the tank… there is a small amount that can sit lower than the drain valve can drain…

This water takes time to get absorbed into the fuel…

You can speed it’s absorption using the recommended fuel additive/alcohol…. Or suck it out with a tube…

Each wing rib has drain holes… at the bottom… the lowest hole is still not on the bottom….

 

POHs in the mid 90s include instructions for fuel additives…. The O’s POH does…

Ice crystals are nasty… they may wait a long time to form, and then show up on the last screen possible…

The alcohol works really well it attracts the moisture and holds onto it… and spreads it all out throughout the tank… at the molecular level…

It is harder to form ice crystals when the water molecules aren’t right next to each other…

 

proper mixing is important… you want it to spread throughout the tank… so, best to add just prior to fueling…  it can be an extra challenge to stir a whole tank….

If ice is already formed… adding the alcohol may take a really long time for the ice to melt then get absorbed…

The good news… you don’t need to be a chemist to know what works….  
 

It’s amazing that the ice stayed around long enough for you to find it…  some mechanics would probably want to bring the plane in to get it warmed enough to work on… crystals are very fine and easily warmed above their melting point…

PP thoughts only…

-a-

[glenn reynolds]

this was a really helpful post.  I fly in the cold (my personal record is -40) and I've just ordered the iso prop alcohol you suggested.  thanks.  

[EricJ]

1 hour ago, glenn reynolds said:

this was a really helpful post.  I fly in the cold (my personal record is -40) and I've just ordered the iso prop alcohol you suggested.  thanks.  

-40C or -40F? 

 

...yes, is joke.