Preflight those fuel vents

[KB4]

Just talked to an Mooney Driver who lost power at 200 feet on final and dead sticked it in. Problem was a clog in fuel vent which caused a vacuum, and after 15 minutes the pressure was enough to completely stop the flow.  Uses one of these T-handle Allen keys to make sure it’s clear now.  On ground he heard pssssssssssstss when he stuck the allen in the vent. 
 

Adding to my preflight. 
 

 

[hammdo]

Humm. Gotta link to that tool?

-Don

[RobertGary1]

2 minutes ago, hammdo said:

Humm. Gotta link to that tool?

-Don

It’s a generic tool. 
 

https://www.harborfreight.com/6-piece-offset-star-drive-wrench-set-42926.html

-Robert

[0TreeLemur]

Any indication of the cause of the blockage?   Plane parked outdoors?  Insects?   Curious of the situation that led to this problem.

Thanks.

 

[toto]

Anyone have a photo of where exactly you stick this thing during preflight to ensure the vents are clear?

[hammdo]

46 minutes ago, RobertGary1 said:

It’s a generic tool. 
 

https://www.harborfreight.com/6-piece-offset-star-drive-wrench-set-42926.html

-Robert

I have a set of those from HF! Simple enough ;o)

-Don

[Niko182]

37 minutes ago, toto said:

Anyone have a photo of where exactly you stick this thing during preflight to ensure the vents are clear?

I dont know where it is either.

[kortopates]

1 hour ago, toto said:

Anyone have a photo of where exactly you stick this thing during preflight to ensure the vents are clear?

 

21 minutes ago, Niko182 said:

I dont know where it is either.

They're small tube pointing into the wind on the bottom of the wing to the side past the tank. In the modern Mooney's they are in a small NACA duct embedded into the wing bottom pointing into the wind. Vintage Mooney's they can be aluminum tubing come down and making a 90 bend into the wind. Those with bladders will see a de-ice mast directly in front of the vent tube.

This usually happens from insects nesting in the tubes when parked on the ramp.

I personally wouldn't insert something as large as a allen key wrench into the vent tube. Instead I recommend using some .032" safety wire to wiggle it in the tube and break up any debris without allowing any chance of ramming it further back into the vent or give it any chance of getting sucked into the tank by the vacuum. I fear the tool will break it up by pushing most of back in, rather than allow it come out.

I can probably get a picture of a modern one later today.

Edited November 19, 2020 by kortopates

[ArtVandelay]

I made up covers using plastic hose to slip over them, similar to pitot tube.

[EricJ]

I've tried to keep it reflex that on power loss the first thing that happens is the tank selector gets switched and the boost pump turned on.   At 200 ft if the field is made it may not be worth it to bother with it, but otherwise it'll cure something like a tank vent getting clogged.

This is definitely a good reminder to check them during preflight, at least visually.

[DanM20C]

I discussed the dangers of clogged vents with a student of mine and the next time we met up he had a clever device that he fabricated.  It was just a rubber plunger type thing with a short bit of small hose attached to it.  During preflight, with the fuel cap off he presses this thing down over the opening and gently blows into the tube.  We experimented with plugging the fuel vent with our finger and the additional resistance when blowing was very apparent.  I was going to make one for my self and completely forgot until this thread.  I'm off to the hardware store.

Cheers,

Dan

[Guest]

I use a length of hose which is a slip fit over the vent tube, then with the fuel cap off and your ear at the opening, blow by mouth into the the hose.  You should feel no resistance to air flow and should hear/ feel air in your ear.

If not, investigate.

Clarence

[RobertGary1]

We used to have an Aeronca at a local grass field that we let pretty much anyone around fly. It was a kick around plane. One day a friend called and said he had issues. He took off, lost the engine, turned back. He checked the fuel, etc. Everything looked good. Hand started it, ran it up, all good. Took off again and again lost the engine. After the third time he gave up. We replaced the vented cap.

 

-Robert

[GeeBee]

My next door hangar neighbor was killed in a Commander 114 from insect clogged fuel vents. Took a flight instructor and father. of two with him. As you can see it was a shake and bake. Despite a board certified Trauma doctor on scene almost immediately, nothing could save them from the burns. 

Check your vents and be very suspicious if your hear a "wheeze" when you open your tank caps.

 

https://www.gainesvilletimes.com/news/investigation-begins-into-thursdays-fatal-plane-crash/

 

[jetdriven]

I just fixed an issue like this on a twin Comanche, he had a new fuel bladders put in, but the vent is actually part of the filler neck of the aircraft, but the gasket had no hole to pass the air through to the Aux tank vent , he noticed the wheezing noise when he removed the caps and the inside of bladder look kind of collapsed. And that’s what it was doing it was sucking the bladder inside the wing like a Capri Sun bag.  I guess whenever they installed the bladder they didn’t blow into the vent to verify that it was working

[carusoam]

My M20R suffered a clogged tank vent...

There are a couple of signs going on that may be difficult to recognize...

Plus there is a spare fuel tank to get you out of the trouble you are in...   

1) Dirt daubers are great insects... they have the ability to fill a tube with mud while building a nest... a single bug.

2) Some small dirt tracks may get left near the tube...

3) Our tanks are not normally pressurized... so... if for any reason, when you inspect the fuel level visually, and a puff of air gets released... that is a certain hint something isn’t right...

4) Let say you missed the first three signs... you are flying along and everything is going fine and dandy... and you look out the window.... and one of your wings is starting to take on a new shape... called oil canning..... (you have to remember oil cans, and them being emptied without a vent...)

5) I’m amazed at how strong the fuel pump is at sucking against a vacuum...

6) Final dual hint... when you open the fuel cap on the ground, some hiss, and a big thump of the wing going back into its original form....

7) This was at a tie-down in NJ... I didn’t know we had dirt daubers there before...

8) a year or two later... a dirt dauber set up a nest on one of the gear tubes... inside the hangar...

9) the fuel vapors will keep them from going very far into the tube... the actual mess will be very close to the end of the tube.

 

Somebody, probably José posted a solution about leaving a permanent safety wire in the tube...  the bugs don’t like the wire,  and the loose wire gives another hint if it isn’t loose any longer...

See... not all of my old stories are about my fully worn down M20C... 

PP thoughts only...

Go Mooney!

Best regards,

-a-

[Mooney in Oz]

14 hours ago, ArtVandelay said:

I made up covers using plastic hose to slip over them, similar to pitot tube.

I have the same together with a 'Remove Before Flight' red flag attached to each cover.

[KB4]

18 hours ago, 0TreeLemur said:

Any indication of the cause of the blockage?   Plane parked outdoors?  Insects?   Curious of the situation that led to this problem.

Thanks.

 

Hanger, best guess was insect.  

[corn_flake]

[KB4]

Couple ping pong balls. I’m gonna stick a hot drill bit to melt away a passage, then just slip over the vent. 

[PT20J]

1 hour ago, KB4 said:

Couple ping pong balls. I’m gonna stick a hot drill bit to melt away a passage, then just slip over the vent. 

Might work in a hangar, but I bet they’ll get carried off outside if there is much wind. I lost two pitot covers until I switched from the type held on with a Velcro strap to the rubber sleeve type.

Skip

[EricJ]

38 minutes ago, PT20J said:

Might work in a hangar, but I bet they’ll get carried off outside if there is much wind. I lost two pitot covers until I switched from the type held on with a Velcro strap to the rubber sleeve type.

Skip

I've lost chocks in Rapid City on two separate occassions in wind storms!   I got the kind that bungee together around the tire now.   

 

[RDuplechin]

A previous owner fabricated (for lack of a better word) a screen that goes over the vents of my 20E.  A few tight wraps of fine safety wire holds them in place very securely.  I have no doubt it keeps the insects out.  The only downside I can see would be it would be easier to ice up.  That is not a big consideration for me so I chose to leave them even though I was pretty sure this wasn’t a factory solution even before I read this thread.  Does anyone seen any obvious danger to leaving them in place other than the increased chance of icing?

[ArtVandelay]

I've lost chocks in Rapid City on two separate occassions in wind storms!   I got the kind that bungee together around the tire now.   
 

Are you sure someone didn’t “borrow” them?

[EricJ]

1 hour ago, ArtVandelay said:

Are you sure someone didn’t “borrow” them?

It's possible, but both times were after big wind storms where I had to retrieve other stuff that got blown around as well after a ramp search.    I think one time I did find the chocks downwind, but this year they were just gone, as was one of the little flags from my cowl plugs.   Airplane was fine, though!