Fuel panel leak

[bradp]

Hi all

Discovered a fuel leak coming from what appear to be two screws on a lower panel.  Read DMax article and what was available her and have a couple of questions.  

By DMax article, seems like nut plate cracks are the typical culprit in this circumstance.   He says remove a screw, apply sealant to the thread and replace.   Wow sounds easy.  But this is a Mooney fuel tank system after all.   

1) Screws are seized.  I don't want to damage them and am afraid of creating new leaks on this panel if I take an impact to them.  

2) the panel location is just below the filler cap, so I can get a great visual on the sealant there.   Looks like a minuscule crack in the sealant along the nut plate   

 

IA is on vacation, so we'll be talking when he returns.  What is the group consensus - remove panel and reseal or patch seal from inside?  Seems like option 2 would be the good is better than perfect option but I'm hesitant to add layer upon layer of Proseal.   

 

Thanks as always 

 

Brad

 

[N201MKTurbo]

It looks like that panel has ben off before. The problem is if you don't clean the old sealant out of the screw holes on the panel before you re-install it, you will get so much sealant in the nut plate that it will push the back of the nut plate off causing a leak. You may get by just taking the screws out and re-sealing them, but the proper fix would be to remove the panel, clean the mating surfaces, both the panel and tank sides, clean the old sealant out of the nut plates with a drill bit (with your fingers don't use an electric drill). Put sealant on the back of any nut plates that have ruptured and then reinstall the panel with new sealant. That will be about 3 hours work if you know what you are doing.

[bradp]

Yes I think the panel was off in 2003 or so when the tank was fully revealed.  Any advice how to get those sealed-up screws off without stripping or needing to drill them out to do the proper reseal?  

 

Thanks

 

Brad

[Guest]

Buy yourself a good quality screwdriver bit, they should not be too difficult to get out.

Clarence

[N201MKTurbo]

The screws should come right out. The hard part is getting the panel loose after the screws are out. This is the tool to use:

http://www.aircraft-tool.com/shop/detail.aspx?PRODUCT_ID=SWG7

It will pry the panel loose without damaging the paint. Push it into the joint and wiggle it up and down until it is in about an inch. Work your way around the panel until it comes loose.

[carusoam]

Adding to the topic...

would you guys go with SS screws when replacing the old ones in this application?

Screw driver bits have a tendency to wear with hard use.  Buy a set of five or so.  They are not very expensive.

use hand torque to first loosen.  Feel and control is a bit better. Less chance of destroying the head.

Using an old power driver bit may quickly round out the screw and given you the benefit of learning how to drill out the old hardware's head.

CAUTION: Power drivers and 100LL are not compatible.  They have caused a few Mooney and other fires for the new mechanic crowd. Make sure the tank is empty, dry, and well ventilated.

I am only a PP, but the fire in the Maint. hangar was memorable...

Best regards,

-a-

 

[Yetti]

Snap on screw drivers have a place to put a wrench on them plus they tend to grip well. Pressure with one hand wrench with the other.  There are two different #2 phillip heads.  Get them both and use the proper one.  Sometimes giving them a little tighten then trying to loosen.  You will need to chase down a snap on truck or maybe they have online sales these days.    Next step I used on access covers if the head got buggered was to cut a slot in them with a cut off bit on a dremel tool.  Avgas fumes and sparks are a bad idea.  Outside is not always a bad thing. 

[Guest]

Try bits made by Apex.  Before trying to cut a slot in the screw head for an even worse slotted screw driver get some diamond valve lapping compound, put a dab in the Phillips head then insert the screw driver bit.

Clarence

[MB65E]

Apex 446-2X bits are awesome!!

You'll be amazed and never buy another type again.

-Matt

[bradp]

I have snap on bits now - mechanic I did an owner assist annual gave me some as a gift and told me to throw out my crappy ones.  They do make a difference... I'll try the apex ones Clarence suggested.  

[Yetti]

The valve lapping compound is the other trick.  Usually the wrench on the screw driver is most workable.  I just had to do that tonight on a disc rotor on a mtn bike wheel tonight...

[bradp]

6oz tube of CS-3330-B2 should do it for a single panel I'd guess...?

 

Also here is a pretty good overview of the different sealant brands and which catalog numbers map to which mil spec . 

 

http://www.vansairforce.net/articles/tank_sealant.pdf

[Mooneymite]

Try this:

http://www.all-spec.com/products/446-2X.html

[bradp]

One of the good things about PIttsburgh is that we have no shortage of business to support the mechanical trades / heavy industry.  

 

Got a whole bag of them from a shop about 1/4 mi from my work. :-)

[markejackson02]

Having spent a week removing access panels and drilling out screws on my 201, I would be really curious to hear why the Apex bits make such a difference.

My experience is that you need to use a good (Snap-on or the like) screwdriver to start them and can then use a power driver to finish removing them.