Tanks not breathing

[agpilot]

Goodday,

I have a 252 with longrange tanks. ( Two each side ) Yesterday as I  reached 6000'

descending from FL 105 I noticed that the tanks on both wings were sucked in. It remained like that after landing and was only relieved once I open the main's caps. It was rarther alarming!

How does the breather system connect and  why did it affect both sides ? Where are the inlets?

 

Thankyou, Danie.

[Guest]

Something has blocked both of your fuel vents on the lower wing surface. I would not fly until you get them cleared, it could be fatal.

Clarence

[FlyWalt]

Considering the critical function of the fuel tank vents, I find it interesting that there are no covers made specifically for them. Unlike the pitot tubes which have multiple vendors offering covers.

 

Regards,
W

[Mooneymite]

On a friend's plane, the vents had been shut off by mud dobbers. No external visible evidence, but a wire passed up though the vents confirmed impacted mud.

[Piloto]

Danie

Before next flight check the following:

1. Take the aux. tank fuel cap off.

2. Have someone blow air by mouth into the tank vent near the leading edge. You will need a 3/8" hose for this.

3. Listen through the aux. filler hole for air rushing in.

4. Cap the aux. tank and un cap the main tank vent.

5. Listen through the main filler hole for air rushing in.

If you do not hear air rushing in there may be a blockage or something wrong with the tank venting.

José

[Yooper Rocketman]

Goodday,

I have a 252 with longrange tanks. ( Two each side ) Yesterday as I  reached 6000'

descending from FL 105 I noticed that the tanks on both wings were sucked in. It remained like that after landing and was only relieved once I open the main's caps. It was rarther alarming!

How does the breather system connect and  why did it affect both sides ? Where are the inlets?

 

Thankyou, Danie.

Danie,

 

Not sure anyone has completely answered your question, as you wanted to know where the vents are located.  They are under the wing on my 231/Rocket/K model, so think probably the same for your plane.  Look under the wing outboard of the fuel tanks and you will see an indent in the wing with a small tube in the indent.  That is your fuel tank vent.  They are separate vents for each wing, which means both of them must have been plugged.  Mud dobbers, as mentioned before, are a likely candidate.  You can visually inspect the ends of the tubes and/or you run a wire up them.  You definitely want to verify they were plugged and have cleaned them out or you may have had some other issue.  If you can't verify by that method, then do as Jose` describes, checking them by blowing on them.  If nothing is found via these methods, and you are sure the vents are now open, then is it possible you were in some precip that may have frozen them?

 

I agree with Clarence, this is serious and needs to be investigated until you are sure what caused the issue.

[carusoam]

Add another data point...

My R got the mud dauber challenge. Being outdoors at a tie-down in spring...

Noticed a slight vacuum when I opened the tank for fueling...

Good thing to add to the checklist if you are outdoors.

Best regards,

-a-

[mike_elliott]

Not long ago after reading a post similar to this I ran a wire through both vent tubes.

Now, reading this again, I wonder if I should attach a wire on a ring to the fuel sump thingy and do it each preflight?

Shove a piece of safetywire up each vent and leave it there. Really discourages the little daubers from selecting your hole to plug. It wont fall out. 

[Guest]

You could easily make plugs for the vents. McMaster Carr sells tapered silicon plugs of many sizes, those with red flags attached would do the trick.

Clarence

[agpilot]

Thakyou all, you are very helpfull, I have posted a reply but our signal strength is different shades of zero. I will try again later.

Danie.

[agpilot]

That was Thankyou !

[chrisk]

Maybe it is just me, but I think fuel tank vent plugs are a horrible idea.  How many planes have crashed because folks forgot to pull off the pitot cover, and that is with a pilot not noticing the ASI being dead on take off.   Imagine getting your bird up into the flight levels and realizing you forgot to pull out your fuel tank vent plugs.   It sound like a bigger problem then mud duabers. 

 

On the other hand, a mesh cover (screen), would prevent insects from crawling in the vent tube and still allow it to vent if forgotten.  It would not be perfect, as it would probably be more likely to ice up. 

[aviatoreb]

Maybe it is just me, but I think fuel tank vent plugs are a horrible idea.  How many planes have crashed because folks forgot to pull off the pitot cover, and that is with a pilot not noticing the ASI being dead on take off.   Imagine getting your bird up into the flight levels and realizing you forgot to pull out your fuel tank vent plugs.   It sound like a bigger problem then mud duabers. 

 

On the other hand, a mesh cover (screen), would prevent insects from crawling in the vent tube and still allow it to vent if forgotten.  It would not be perfect, as it would probably be more likely to ice up. 

 

Then you need a heated mesh covered vent hole.

[Shadrach]

Goodday,

I have a 252 with longrange tanks. ( Two each side ) Yesterday as I  reached 6000'

descending from FL 105 I noticed that the tanks on both wings were sucked in. It remained like that after landing and was only relieved once I open the main's caps. It was rarther alarming!

How does the breather system connect and  why did it affect both sides ? Where are the inlets?

 

Thankyou, Danie.

 

Do you have any enemies? 

[Shadrach]

Then you need a heated mesh covered vent hole.

 I think the vents are designed in such a way to prevent icing without the need of heat.  

 

Covers do get forgotten.  I see many aircraft tattooed with little red "remove before flight" covers all over everting that can be covered yet occasionally they still stay on for flight. It seems to me that it would be best to use something that is not air tight.

 

The easiest way to solve this is to simply blow in the vents at each preflight...  for those of you who find squatting under the wing undignified, why not buy a length of fitted PVC hose to slip over the vent tube and blow through that.

[Piloto]

Unlike pitot tubes bugs normally do not get into fuel tank vents due to the poison fuel vapors coming out unless the tanks were empty. Vents are designed to be close to the skin to avoid the icing flow.

José

[chrisk]

Vents are designed to be close to the skin to avoid the icing flow.

José

 

Yes, the ice blocking effect is designed into the fuel vents.  It's why they are recessed or behind struts in other planes.   I don't know if this ice blocking is defeated when half an inch of safety wire is sticking out of the fuel vent and into an unprotected air stream.  Thin objects are known for their ability to collect ice.

[mike_elliott]

Yes, the ice blocking effect is designed into the fuel vents.  It's why they are recessed or behind struts in other planes.   I don't know if this ice blocking is defeated when half an inch of safety wire is sticking out of the fuel vent and into an unprotected air stream.  Thin objects are known for their ability to collect ice.

Don't stick it out into the airstream. Just put it in the vent. Never collected ice for me flying in the Great lakes region for years, while getting ice on other parts of the plane. 

[agpilot]

I spent the whole day getting the wasp's artwork out of the vents. Both sides were blocked very solid and  no matter how many times

I ran a wire through, I could not clear them. I had to remove all the inspection plates where the tube runs on the left side and detached it

from a short rubber hose just before it enters the tank. Once the tube was out of the wing, it was easy to clean of course.

The right was more tricky since there are not as many inspection holes. With an air hose attached to one side, and the tube once again detached

from the tank I could blow the baby wasp out.

I made plugs with red ribbons tied to them. I know it's possible to forget to remove them but I will risk it.

I will still add the blow through procedure to my preflight inspection.

 

Shadrach asks if I have enemies. I know I have, I'm a cropsprayer... all insects must hate me.

[Shadrach]

Don't leave anything (safety wire or otherwise) in those vents during flight.

[Yooper Rocketman]

Great news, that you found it anyway.  Pretty amazing they decided to collect in BOTH vents.

[Shadrach]

I spent the whole day getting the wasp's artwork out of the vents. Both sides were blocked very solid and  no matter how many times

I ran a wire through, I could not clear them. I had to remove all the inspection plates where the tube runs on the left side and detached it

from a short rubber hose just before it enters the tank. Once the tube was out of the wing, it was easy to clean of course.

The right was more tricky since there are not as many inspection holes. With an air hose attached to one side, and the tube once again detached

from the tank I could blow the baby wasp out.

I made plugs with red ribbons tied to them. I know it's possible to forget to remove them but I will risk it.

I will still add the blow through procedure to my preflight inspection.

 

Shadrach asks if I have enemies. I know I have, I'm a cropsprayer... all insects must hate me.

 

 

Had the plane sat for a period of time with no fuel in the tanks? Like José, I had assumed that insects would shy away from the vapors.  That theory is blown...  Perhaps this was insect retribution brought on by the years of carnage delivered by your sprayer.

[mike_elliott]

 

 

Shadrach asks if I have enemies. I know I have, I'm a cropsprayer... all insects must hate me.

 

 

One word....Karma

[mike_elliott]

Don't leave anything (safety wire or otherwise) in those vents during flight.

I guess I have to ask why not here. I literally had safety wire in the vents of my F for over 14 years without them coming out, getting sucked in, nor having them plugged up by mud daubers. They wont fall out, really. You have to pull them out with small needle nose pliers. I didn't have to worry about removing them before flight like I would have caps. Keeping your plane inside a hanger wont help, the daubers like it indoors also. Every IA that has looked at my plane really liked the idea (and it wasn't mine) to boot. Being removable, it is not against the regs.  

[chrisk]

I guess I have to ask why not here. I literally had safety wire in the vents of my F for over 14 years without them coming out, getting sucked in, nor having them plugged up by mud daubers. They wont fall out, really. You have to pull them out with small needle nose pliers. I didn't have to worry about removing them before flight like I would have caps. Keeping your plane inside a hanger wont help, the daubers like it indoors also. Every IA that has looked at my plane really liked the idea (and it wasn't mine) to boot. Being removable, it is not against the regs.

 

I like the idea.  It's kind of like a giant IUD (birth control) for your plane.  --So, how long were the wires?  I assume there is a bend it needs to go around or it would fall out.