Does The Mooney Wing Tank Hide Water?

[GeeBee]

From time to time my M20R would give a "stutter" of less than a second. I had a hard time figuring it out and I got three in one flight enough to generate some data.  I asked Savvy to look at the data and our own Paul Kortopates said he thought it was water.  I always sump the snot out of my tanks and wait the required 5 minutes after fueling to check the sumps again (now I wait 30 minutes). I drain the wing sumps first then the floor drain per the AFM. I use a GATS jar and fill it completely during sumping so as to create a strong flow towards the drain. I discard the drained fuel after examination. I change the tank cap seals every annual with the blue ones as well and make sure the cap is adjusted to MM specifications.  I keep my tanks at least half full in the hangar, but I noticed the lower the level, the more likely a stutter (sometimes on climb out, sometimes in cruise) would present.  At the suggestion of Paul, I treated the tanks with a 1% volume of 100% pure isopropyl alcohol. All stutters have stopped. I now do that on every servicing, keeping the concentration at 1%. No issues since.

This got me thinking about the construction of the tanks and about other similar aircraft. Piper Malibu (recip PA-46) have had a lot of problem with water condensation and precipitation at altitude and sometimes freezing (including several engine stoppages). Wet wing Cessna Skyhawks had a huge problem with water entrapment (and a lot of lawsuits) until Cessna added several sump drains to out portions of the wing, besides the usual by the door. There appears to be no consistent points in these aircraft where water hides and when one thinks about it, the inconsistent part of the tank is the sealant placement. I am also sure there are places where sealant obstructs openings in the stringers and ribs where there should be adequate flow for moisture to easily makes its way to the sump drain. Obviously some airplanes drain better than others, so I am sure the experience is varied. Has anyone else seen this on Mooneys?

[A64Pilot]

The 210 used to if left out in the rain and only one wing, pretty sure it was getting in through the cap.

But you could sump it and get no water, then shake it pretty hard by pulling down on one wing several times, and sump it and get water. 

In its case I supposed without any proof that the bladder had a wrinkle in it that acted like a dam and trapped the water.

But if you think you’re getting water, I think you need to find the source, in a couple of decades of managing aircraft I never saw any water. We closed circuit refueled only though. Jet has water dissolved in it, so in theory it could precipitate out, don’t know about Avgas.

I’m not sure I believe the condensation theory, or our cars would get water and I’ve never seen that either. I’ve stored vehicles for years and never gotten any water.

So in other words If I suspected water I’d try to stop it from getting in as opposed to being concerned about entrapment, but I also believe vigorous shaking will most likely free most trapped water, enough to find when you sump anyway, and you should find it in the gascolator after you shut down, some drops in and doesn’t flow through, That’s how you find water in a gascolator, from the previous flight I believe.

Water in the tanks should be in the tank sump, with the fuel pickup slightly higher so just sitting there water shouldn’t flow out of the wings unless there is a lot.

There is also water detecting paste we used in the bulk tanks to check for water, looked silver and turned purple if there was any water,  put some on a dowel and move it around everywhere you can, if there is a drop of water it will turn color

https://www.amazon.com/Kolor-Kut-Ounce-Water-Finding/dp/B00905UC5E/ref=sr_1_6?gclid=CjwKCAiAqt-dBhBcEiwATw-ggCIzHPsTtlDRSgrhkySoELNGtZud4U6DAdtA7hklbNKiAj83ZVuKWxoCWcYQAvD_BwE&hvadid=531861639580&hvdev=c&hvlocphy=9011535&hvnetw=g&hvqmt=b&hvrand=14252240248949256036&hvtargid=kwd-833600341875&hydadcr=15308_10335526&keywords=water+detection+paste+for+fuel&qid=1673051566&sr=8-6

You can find it at Tractor supply etc and I bet your airport has some too.

[GeeBee]

16 minutes ago, A64Pilot said:

Water in the tanks should be in the tank sump, with the fuel pickup slightly higher so just sitting there water shouldn’t flow out of the wings unless there is a lot.

The Cessna experience tends to discount that as a sure thing.

[Niko182]

FWIW at my first annual, when they emptied the tanks to calibrate them, the shop said they found a large sum of water in both tanks. I always sump my tanks and have rarely seen water within the cup, so I was quite surprised. I came to the conclusion that the tanks, or at least mine hide a bit of water. I rarely get a mis or a stumble, but when i do, I figure a couple drops of water just got through the the fuel line, as its too short for the EGTs or CHTs to pick up.

I guess I should also start adding alc to the tanks. What does the 100% IA do to the water in the tanks?

[GeeBee]

Interesting. You have a long body like me as well. 

22 minutes ago, Niko182 said:

What does the 100% IA do to the water in the tank

IA is soluble with the water. 50% IA (50% IA and 50% H2O) will easily burn, so a small amount of 100% IA will combine with the water and pass and burn through the engine harmlessly.

[Niko182]

Just now, GeeBee said:

Interesting. You have a long body like me as well. 

IA is soluble with the water. 50% IA (50% IA and 50% H2O) will easily burn, so a small amount of 100% IA will combine with the water and pass and burn through the engine harmlessly.

Yes. We have an identicle wing except i have a tab thats slightly lower than yours, however with the O3 conversion I can legally fill up past the tabs now.

[EricJ]

The SMM for the J model says that Isopropyl Alcohol can be added to the fuel tanks but it needs to be thoroughly blended with the fuel not to exceed 1% of the total by volume.   I think part of the reason for this is that IA is a bit of a solvent for the tank sealer, so there's a small tradeoff to using it.   Adding some just before a trip to suck up rogue water and then burning it off the same day is probaby very low risk to the sealant.

FWIW, I had a lot of trouble with water in the tanks when I first bought my airplane, and it seemed to persist in there for a long time after the events by which it seemed to have been introduced.   So the theory was that it was hiding behind some ribs and just popping out when it seemed so inclined.   Rich,  N201MKTurbo, suggested grabbing each wingtip and shaking it vigorously up and down for a while, and when I did that I got a bunch more water at the sump and never any since.

[N201MKTurbo]

The Mooney tanks have a lot of ribs and channels that can hide water. They all have drain holes to let the water flow to the bottom. The problem is these drain holes get plugged with sealant when the tanks are sealed, sometimes even from the factory. There is an AD to check these drain holes. The problem is it is almost impossible to inspect all of them without opening the tanks. Even if you find a plugged hole, they are hard to fix. If you poke a wire or poker through the hole, it will pierce the sealant and push a flap of sealant aside, but after you remove the poker the flap closes again. You have to scrape the sealant off the hole from both sides. This is hard to do even with the tanks opened up.

[ilovecornfields]

If all you get is an occasional stumble for a second it is really worth the potential damage isopropyl alcohol can do to your fuel system?

[kortopates]

A little bit of IPA goes a long way to dissolving a little trapped water. Don’t need to go as much as 1%. The turbo’s allow upto 3%. It’s turns out the casualty to excessive IPA is not the tank sealant but the seals in the TCM engine driven fuel pump. But have only seen this when using the maximum 3%, never 1%.
I always recommend using it as needed conservatively.


Sent from my iPhone using Tapatalk

[A64Pilot]

Do you guys get water in your fuel as a normal thing?

I never get water in my fuel, the only time I have in 40 years was if the airplane was left outside in the rain and I’m sure was the fuel cap leaking as it was only the left wing.

You shouldn’t be having to treat your fuel for water, you should instead be looking for the source of the water and eliminating the source.

Where you get fuel whether it be a truck or fuel station should have a water absorbent filter, so you should not be getting any water there.

Don't treat the symptom, cure the disease.

Yes I know we have multiple drains for water, but you should never get any, if you do you have something to fix, even if the fix is where you get fuel.

‘When was the last time you had to have water remove from your cars fuel tank?

Water in fuel isn’t normal

[Hank]

Fifteen years, no water. Even sitting outside away from home in significant thunderstorms.

Replace the orings in your fuel caps--the big one around the outside, then disassemble the cap and replace the little bitty one around the center shaft. Do both caps. Use blue fluorosilicone orings and you won't need to replace them very often; if you use regular black Vinton or butyl orings, replace then all at every annual. 

[GeeBee]

9 minutes ago, Hank said:

Fifteen years, no water. Even sitting outside away from home in significant thunderstorms.

Replace the orings in your fuel caps--the big one around the outside, then disassemble the cap and replace the little bitty one around the center shaft. Do both caps. Use blue fluorosilicone orings and you won't need to replace them very often; if you use regular black Vinton or butyl orings, replace then all at every annual. 

Read my OP

[GeeBee]

34 minutes ago, A64Pilot said:

Do you guys get water in your fuel as a normal thing?

I never get water in my fuel, the only time I have in 40 years was if the airplane was left outside in the rain and I’m sure was the fuel cap leaking as it was only the left wing.

You shouldn’t be having to treat your fuel for water, you should instead be looking for the source of the water and eliminating the source.

Where you get fuel whether it be a truck or fuel station should have a water absorbent filter, so you should not be getting any water there.

Don't treat the symptom, cure the disease.

Yes I know we have multiple drains for water, but you should never get any, if you do you have something to fix, even if the fix is where you get fuel.

‘When was the last time you had to have water remove from your cars fuel tank?

Water in fuel isn’t normal

If you fly in weather you have to be getting water, where does the tank vent to? Cars used to get water, in fact corroded gas tanks were common, but not after vapor recovery systems were mandatory which closed the system. 

[A64Pilot]

Fuel vent should be designed to not get water, the Thrush we drilled a small hole in the backside of the vent, have since 1965. Not sure about how Mooney does it so I have bladders and they don’t use stock vents

Yes I’ve flown in rain so hard you couldn’t hear the engine, nor see out of the cockpit several times, so loud it sounded like hail. Cross the Intertropical Convergence zone and or fly around in Central America enough and you’ll see what I mean, and still never got water.

If you get water when you sump your fuel that’s not normal, you need to find out where it’s coming from and fix that before it causes an accident.

My 1923 Model T has its original fuel tank, it’s 100 yrs old, it’s not corroded out, the 53 Jubliee Ford tractor I used to have the same, none of my farm tractors and backhoe had any rust in their fuel tanks. I don’t doubt some people may have gotten water in their fuel and that led to rust. I had to clean and coat the fuel tank i’m my old race bike, but I’d bet that came from the cap being left open or something, race bikes are often put together and or repaired with parts from the junkyard.

So yes water does get into fuel sometimes that’s why we check because it’s possible, but it’s not normal.

Even sumping water is problematic, if it’s below freezing it’s not likely your going to get any water to drain as ice doesn’t drain, so fix the water intrusion problem.

[GeeBee]

No liquid vented to the atmosphere can remain anhydrous. It is chemically impossible. It will either develop as entrained or free water. If it is entrained, it will eventually precipitate to free water by a number of actions, some internal, some external. 

The question here is not if you get water in your sump, the question here is does the sump drain all the water?

Apparently the answer by three careful and conscientious pilots, an SB and AD is in wet wing installations, the answer is no.

Which is why the presumption has to be, there is always water.

Just as the SEC gave Bernie Madoff a clean bill, three times in 15 years, but yet there was massive fraud.

Because you don't see it by the test, does not mean it is not there. It only means none observable

[A64Pilot]

Yes water is dissolved in fuel, we used to have to run an agua-glo test before any fueling and if it was above some number of parts per million we would have to recirculate the fuel through the water absorbing filter until it met specs.

https://www.gammontech.com/files/manuals/AquaGloPowerPoint.pdf

You don't test Avgas because it’s just not a problem with it

Jet and Diesel can hold a lot more water than Avgas, by a large factor, dissolved water just isn’t much of an issue in Avgas or we would get water every time it turned cold and we don’t, we don’t in Jet either even if it’s much more likely.

If water were normal, we would have a water separator that could hold more than a couple of ounces and we don’t.

I cant imagine getting slugs of water in my fuel system making the engine stumble, if that were true it would worry me. If water is passing through the gascolator then it should be pretty full after a flight. It’s purpose is to separate water of course, so if you drain it after a flight and get any significant amount I’d investigate it.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-125.pdf

I still maintain if draining your sumps you ever get water except for a rare occurrence in any amount, you have a problem, and if you ever get any significant amount of water, for me I’d say an ounce, you really should investigate it, it’s not normal, don’t accept water in fuel as being normal, it’s not.

I’ve flown too many years and in just about every conceivable type of weather from jungles to deserts and in very cold weather and never had water of any significant amount, mostly Jet which is way more likely to have water, jets have crashed from filtering a small amount of ice from a large volume of fuel, it’s why turbines heat their fuel before it flows into the engine, but it’s not enough water to fall out of suspension, but yes there is water in fuel, not much in Avgas but there is some, measured in parts per million, so not much.

Lower the temp until the fuel hits saturation and water can come out, but the fuel should be too dry for that to happen, but it’s possible.

I’ve never seen it, but accept the possibility. 

 

 

[larryb]

I add one of these every few fillups. It results in 0.2% for my 75 gallons. I have also experienced unexplained momentary stumbles but not while using the IPA.




https://www.amazon.com/gp/aw/d/B07J62C1K5/ref=ox_sc_act_image_1?smid=ATVPDKIKX0DER&psc=1

[GeeBee]

https://www.euroga.org/forums/hangar-talk/2644-can-water-exist-in-suspension-in-avgas

 

"

"Where did these come from? On that occasion, the plane was fuelled 3 days before the flight and I did drain the tanks and saw absolutely nothing, yet these doplets appared from apparently nowhere…

One possible explanation is that water can dissolve in avgas and remain suspended but will come out of solution (and form droplets which then remain as droplets from then on) if the fuel temperature falls at any time."

[neilpilot]

2 minutes ago, GeeBee said:

https://www.euroga.org/forums/hangar-talk/2644-can-water-exist-in-suspension-in-avgas

 

"

"Where did these come from? On that occasion, the plane was fuelled 3 days before the flight and I did drain the tanks and saw absolutely nothing, yet these doplets appared from apparently nowhere…

One possible explanation is that water can dissolve in avgas and remain suspended but will come out of solution (and form droplets which then remain as droplets from then on) if the fuel temperature falls at any time."

...and if you fuel under relatively warm conditions, and then spend sufficient time below freezing, the water can come out of solution in the form of very fine ice crystals.  In extreme conditions, your fuel filter can be blocked by those crystals.  The real reason to consider adding IPA to fuel in the winter. 

[GeeBee]

 

[jlunseth]

This puzzles me because I have had my plane for 13 years now and never any water. Zero. So much so that I have to work to keep the discipline to sump after every new fuel load. There was a period maybe a decade ago where for about a year I put isopropyl in for most flights. The recommendation was to do that in turbos because at high altitudes even during the summer we are flying constantly in temps that are well below freezing, but I never saw a problem and have discontinued the practice. If I had water hiding in the tanks it might have gotten cleaned out while I was doing that, and never returned. The biggest problem is the O rings for the fuel caps. The caps sit in a slight well, as everyone knows, and if the plane is outside when it rains, water pools up in that well and will find its way into the tanks. I flew a J some years ago that had quite a bit of water in it for that reason. My caps are in good shape and I have kept them that way, so no water. Just have never seen any at all. No engine stumbles because of it either. I fly in the rain quite a bit in the summer too.

Paul Beck at Weep-No-More redid my tanks 13 years ago. Did a superb job and maybe the quality of the reseal leaves fuel no place to hide.

A big difference may be keeping the plane in a hangar. Except when I am on a trip somewhere, the plane is always hangared. It is not rained on much, maybe a few times a year.

Based on that experience I wonder if your fuel source has water in the tank so you are constantly having some introduced? Might want to talk to them.

[Pinecone]

If you are parked outside, there are fuel cap covers to keep the water out of the cap well.

https://wingviewtint.com/products/fuel-cap-covers

 

 

[GeeBee]

2 hours ago, jlunseth said:

This puzzles me because I have had my plane for 13 years now and never any water. Zero. So much so that I have to work to keep the discipline to sump after every new fuel load. There was a period maybe a decade ago where for about a year I put isopropyl in for most flights. The recommendation was to do that in turbos because at high altitudes even during the summer we are flying constantly in temps that are well below freezing, but I never saw a problem and have discontinued the practice. If I had water hiding in the tanks it might have gotten cleaned out while I was doing that, and never returned. The biggest problem is the O rings for the fuel caps. The caps sit in a slight well, as everyone knows, and if the plane is outside when it rains, water pools up in that well and will find its way into the tanks. I flew a J some years ago that had quite a bit of water in it for that reason. My caps are in good shape and I have kept them that way, so no water. Just have never seen any at all. No engine stumbles because of it either. I fly in the rain quite a bit in the summer too.

Paul Beck at Weep-No-More redid my tanks 13 years ago. Did a superb job and maybe the quality of the reseal leaves fuel no place to hide.

A big difference may be keeping the plane in a hangar. Except when I am on a trip somewhere, the plane is always hangared. It is not rained on much, maybe a few times a year.

Based on that experience I wonder if your fuel source has water in the tank so you are constantly having some introduced? Might want to talk to them.

In my case my airplane is hangared, always even even when I am on a trip I pay for a hangar. It sits outside maybe, 5 days a year. As to fuel source, it is highly variable. I rarely fuel at my home base due to prices. However my tanks are always at least half full in the hangar. I still think the variable is the tank sealing.

[EricJ]

3 hours ago, Pinecone said:

If you are parked outside, there are fuel cap covers to keep the water out of the cap well.

https://wingviewtint.com/products/fuel-cap-covers

Those are pretty cool.   I wonder how well they stick in high wind, though.