Mooney down near Boulder, Colorado

[FloridaMan]

Hi Jose,

 This is really a maintenance issue and shouldn't be solved by installing a part that isn't approved for this installation. The -72 will not get all the water out of the tank and by doing so, will allow the opportunity for corrosion to start or accelerate if already present.

 

 David

 

If I understand it correctly, the drain valve refit involves riveting a new plate that changes the overall depth of the valve. 

[Piloto]

If I understand it correctly, the drain valve refit involves riveting a new plate that changes the overall depth of the valve. 

 

You do not need to change the drain plate just replace the valve with the F-391-72. The valve holes on the -72 will be just above the drain nutplate.

 

José

[Piloto]

Hi Jose,

 This is really a maintenance issue and shouldn't be solved by installing a part that isn't approved for this installation. The -72 will not get all the water out of the tank and by doing so, will allow the opportunity for corrosion to start or accelerate if already present.

 

 David

 

I understand your concern. But having an M20C I would do the stream test at least. Specially if your plane is not hangared. Even if you have new fuel cap o-rings water can get in the tank through the filler cap adapter plate.

 

I was lucky to survive the incident and tell about.

 

José 

[Guest]

I must be missing the point here. How is it better to have just a 1/4" of water and debris in your fuel tank caused by installing the wrong drain valve or having a bunch of water and debis caused by partially blocked drain holes in the plate nut?

If your drain valve does not have a good flow while sumping the tank have it checked and fixed.

Clarence

[Marauder]

What's installed on the bladder tanks?

[bonal]

The sump drains, are they the same as the ones in question here if so I can check and see if I have the same concern with not getting all the water out when I sump my tanks.

[Ned Gravel]

If your drain valve does not have a good flow while sumping the tank have it checked and fixed.

Clarence

+1. That is exactly what I did. New valve. Clean holes.

Ned Gravel

Lucky steward of C-FSWR, a '65 E model at Rockcliffe, Ontario, (CYRO)

Sent from my iPad using Tapatalk

[MB65E]

Sad deal all the way around. All the water and junk from the tank should be cleared!! If one is really worked about it, they should remove the sump annually and clear the tank of any debris and water. Or whenever there is a known issue.

Allowing crap in the tank to build up then changing the sump designe to allow it to happen seams counter productive. Am I missing somthing Jose? I usually follow your logic, just having a hard time on this one.

-Matt.

[carusoam]

The logic comes from the most knowledgable resource of mooney fuel tanks...

The detail is more complex than most people realize.

And every situation can be different depending on who sealed the tank last.

Reminder...

Check the fuel neck at the top of the tank. The ring that the cap locks into. They were changed to stainless steel somewhere along the way...

If you see rust on the cap seal, this is a sign that a hole is forming. After 40 years outside, it leads to water in the tank.

Any water in the tank should be considered bad.

Don't over torque the fuel drains. They have a rubber seal. They break easily....

My 65C had the rusty fuel necks that would let water into the tanks. The rust built up in the drains.

I broke the first replacement drain that the mechanic gave me (with the instructions 'do not over torque').

When it comes to tanks...

Get the right tops and bottoms,

-a-

[Tommy]

I think many may well disagree but I do have a simple approach to this complex issue - ask yourself "what would my insurance company say if anything happens with this modification?"

 

After all, both sides have valid points...

[jetdriven]

Insurance companies very rarely deny claims due to improper parts or maintenanc. It's a widely spread rumor but not one with much basis in fact.

[Lionudakis]

A close friend of mine died in a cessna in 05. It had an experimental (superior) engine of larger size and many other undocumented mods. It was his business not mine. Surprisingly nothing ever came out of it, probably because it was a classic stall/spin scenario and they drew conclusion pretty quick, but the ntsb report mentioned the lack of data placard and suspicion of engines origin or something to that effect. Insurance paid out on everything, business as usual. I wouldn't bank on it, but..

[Tommy]

Better to clarify it!

 

Isn't a silly world we live in? A certified GA aircraft can't legally fit non-ceritified parts even though many have been demonstrated to be more superior by our RA friends...

 

Last time I checked both are flying objects travelling at more than 100knots with at least 35 gallons of fuel.

[ShermAv8tor]

The F391-53S seems to be the correct design in my opinion. See this link below with pictures. It doesn't make sense to have the drain holes well above the threads. At worst, with the 53S, you can't drain the fuel if it gets blocked which forces you to inspect the valve and tank for debris, at least you don't get a false sense of security if there is water present below the threads with the -72 version.

 

http://www.bondline.org/wiki/Fuel_Tank_Drains

Its pretty clear to me which one is correct. Thanks Wishbone for sharing.