Fuel tank vent - M20R.

[carusoam]

While running my pre-flight checklist on a sunny Sunday, I opened the fuel cap on right side and a significant amount of fuel vapor pressure was relieved.

[1] Do I have a blocked vent or is it "normal" to have some pressure build up in an ovation fuel tank?

[2] Left side did not exhibit the pressure relief, at least nothing like the right side.

[3] Now, where is the tank vent?  I went to see if a bug built a nest in it like my ol' M20C, but I could not locate the vent.  It is nicely hidden out of view.

Thanks for the help,

-a-

[Piloto]

Quote: carusoam

While running my pre-flight checklist on a sunny Sunday, I opened the fuel cap on right side and a significant amount of fuel vapor pressure was relieved.

[1] Do I have a blocked vent or is it "normal" to have some pressure build up in an ovation fuel tank?

[2] Left side did not exhibit the pressure relief, at least nothing like the right side.

[3] Now, where is the tank vent?  I went to see if a bug built a nest in it like my ol' M20C, but I could not locate the vent.  It is nicely hidden out of view.

Thanks for the help,

-a-

[carusoam]

Jose,

 

You are the best!

 

Blocked vent, cleared with a piece of safety wire.

 

Best regards,

 

-a-

[Piloto]

Glad to know your problem was fix. Little details like this in some cases can cause major accidents like power failure on take off. During annuals and after long time parked on vegetation run the wire into the vents. Also I found that on the M20K thru the M20TN because the vent opening is facing forward it is more prone to get clogged with flying bugs when flying at low altitudes.

José  

[MooneyMitch]

Good knowledge with this, thank you. 

[FloridaMan]

http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=59528697

 

 

 

The main cause of the final crash was fuel starvation that led to engine stoppage, all caused by simple wasp nests that blocked fuel tank air vents.

[podair]

I was going to post a similar question and searched the forum first! Great resource. 

Same thing happened to me last weekend (M20F). Ran right tank nearly dry , then when opening the cap refuelling a significant amount of pressure was relieved (to the point that I needed to apply a bit of force to get the cap off). 

Guess I need to check my fuel vent!

[LANCECASPER]

I had a fuel vent plugged during cruise on a Grumman Tiger 25 years ago. I looked out during flight and saw the wet wing actually compressing in - switched tanks - thankfully plenty of fuel in the opposite tank. Landed as soon as possible and cleared it. Always checked it after that. Thanks for the reminder.

[PaulB]

Makes me wonder if I should be running a piece of safety wire up the vent on every preflight.

[Guest]

Over the years of doing maintenance I've seen a few people insert a rolled up piece of plastic Kitchener scouring pad into vents to keep bugs out.

Clarence

[M20S Driver]

I have ants/bugs near my tie-down and after seeing this post, I decided to check my vent.  I used a hose (from oil analysis kit that was never used)  and pushed it in for 12-18 inches. it was a relatively tight fit.  I could blow air in and had no restriction.  

I assume this is a valid test to tell me that the vent is open. Any thoughts?

[Piloto]

One way to keep bugs out is to keep more than half the fuel in the tanks. Bugs are sensitive to fumes and they will not go any further into the vent because of the fumes. But a curious fat bug may get jammed in the vent and just die breathing the fumes. Also fuel helps in maintaining lower sealant temperatures that will help in preventing future leaks.

If you have a stubborn ants nest were you have tried everything, try MEK. Just pour it into the nest hole. It will kill instantly all the way down to the queen's chamber leaving no ant alive and no evidence. Unlike most pesticide that will not flow easily through dirt, MEK flows down quickly and evaporates quickly with lethal vapors gassing all tunnels and chambers, is a massacre.

José

[podair]

how long is the vent? I tried to clear it on my M20F by pushing some shortish wire up the tube and pushed about 2in up, no resistance , maybe I should use a longer bit of wire. It still pops like a Coke bottle when I open the cap and I can see some compressing of the top of the tank flexing back out when I let the air in. At least I know my O rings are still a good seal! I could also blow some air in the tube to clear it? What happens to the debris? is there a filter on the other side and in the tank lines?

[carusoam]

I tried to look up details on the vents in both the old service and parts manual...

Unable to find any detail on how long the vent is, it could be a meter long?

I was expecting to find a tube that is offset from the bottom of the tank and run all the way to the top before entering the tank.

Open the fuel cap.

Blow air into the vent. Connect a tube for good reasons...

Air should flow freely toward the tank.

Expect no filter or restriction in the vent line.

Any dirt blown into the vent, will go into the tank...

The newer Mooneys use a larger diameter tube and hide it in a backward facing NACA duct...

My bugs wedged themselves in the first couple of centimeters in the tube.

Consider using a vacuum to remove things from the vent line...

As usual, I am not a mechanic. My bug experience was in the vent of my R....

Best regards,

-a-

[BillC]

Finally had the time to review past posts. I came up with a great way for me to protect my fuel vents while at the hardware store. On the checkout counter they had plastic tips used for storing open caulking guns. It fits the vents perfectly. They were 1.00 each. I attached two long 'remove before flight' banners. No more worries when in Florida for the winter.

[Robert C.]

Finally had the time to review past posts. I came up with a great way for me to protect my fuel vents while at the hardware store. On the checkout counter they had plastic tips used for storing open caulking guns. It fits the vents perfectly. They were 1.00 each. I attached two long 'remove before flight' banners. No more worries when in Florida for the winter.

Brilliant, going by the hardware store tomorrow

[mike_elliott]

 

Jose,

 

You are the best!

 

Blocked vent, cleared with a piece of safety wire.

 

Best regards,

 

-a-

 

leave the safety wire in it, it will keep the mud daubers out.

[Healthpilot]

Here is what a Mooney J model vent looks like btw. I couldn't find a picture of an M20R vent.