How should wing roots be sealed?

[bradp]

I wanted to move this to a new thread.  I'll need to have a conversation with my A&P on Monday, but I want to ask your collective Mooney advice. 

I installed new Windows yesterday and after cure took the plane out to leak test it (with a hose in the pouring rain - I looked like a crazed idiot).  

Windows are water tight but I noticed a steam of water that was coming from the strip of horizontal sheet metal  that makes the roof of the box just above the right inboard fuel sender .  It appears the seal is leaking.  It also appears the leak goes back aft the length of the wing as I found a small puddle at the back of my spar.  Yikes.  This has probably resulted from my recent trip to the paint shop.... I need to talk with them tomorrow to figure out how they prepped the wing root.

The learning point is after major surgery (paint) a thorough inspection is warranted.   Had I not been a dummy and wanted to do the windows as a project after painting, I would never had known about this issue until future me has a corroded main spar and is very unhappy.  I'd rather have a moth eaten corrosion free ugly duckling than a leaky lady with pretty lipstick.   She is getting pretty pretty, though (supporting evidence  attached :-) ).  

 

I want to ask what the proper way to seal this area?  Search function and mx manual don't make too much reference to wing root seals and there seem not to be commercially available options.  If my AP recommends, my left over Chem seal might be a good option.  What do you guys think?   

 

Thanks and take care

 

brad

[jetdriven]

Under those L shaped fillet strips that screw to the wing where the fuselage meets It, is duct tape. I went a little further and put PRC sealer on the strips and screwed then down wet. Shadrach has a thread that talks about these. 

Edited July 29, 2016 by jetdriven

[bradp]

Yup definitely a strip of duct tape down there.  

[Pictreed]

Wow.  I'll be following this thread.  Let us know what you find.  I figured I'll leak test mine soon enough with fall coming. 

Tim

[N601RX]

In addition to the seal on top of the wing there is also a large gap down each side of the plane along where the floor meets the sides.  In places it is a couple of inches wide and is just covered with tape.  If there has ever been a prolonged fuel sender leak the tape will turn loose.  McMaster sells a heavier and wider than normal foil tape that is fiber reinforce that will cover the gap well.  It also has a fire or smoke rating , I don't remember which.

[Shadrach]

Worth a read. Make sure all th screws you remove have tinnerman nuts on the back. I learned during this thread that all sheet metal screws have a nut.

 

[bradp]

This would be a much easier project if every little tinnerman nut wasn't 1) too sharp to grab with my hand, 2) reachable.  

In Ross' thread the reference to the mouse boots (I've also heard them refered to as rat socks) is important.  The in the fuselage side of the rat sock is accessible by the inspection panels under the rear seats.  

You can see in this picture some isopropyl alcohol I sprayed on the outside faring working its way under the flange coming off the aft side of the main spar.  The boot would be forward (left) in the picture.  It's a totally flat area with no drainage, so if water collects here it would stay put.  This is looking down through the rear seat inspection panel. This is why this little strip of duct tape is so critical to corrosion prevention  

@N601RX How do you access the place where the floor meets the fuselage sides? I'd like to replace all the tape while I'm at it.  

@jetdriven Byron did you do a strip of foil tape and then PRC on the fillets / fairings or just PRC?

Thanks - brad 

[Yetti]

Technically I think they are speed nuts.   An array of needle nose pliers and several sizes of locking forceps come in handy when you have larger than the average sized bears hands. I think the leading edge ones can be gotten from bottom center panel removal.

Edited July 30, 2016 by Yetti

[N601RX]

Just remove the lower interior panels

 

[Shadrach]

3 hours ago, Yetti said:

Technically I think they are speed nuts.   An array of needle nose pliers and several sizes of locking forceps come in handy when you have larger than the average sized bears hands. I think the leading edge ones can be gotten from bottom center panel removal.

Invented and patented by a guy named Al Tinnerman.

[jetdriven]

I cleaned everything good then put down two strips of duct tape to bridge the gap between the he fuselage side skin and the wing skin. Make sure the outside edge of the duct tape is just about even with the screw holes.  Place the fairing strip on and put masking tape on the strip and the airplane.  Then I put PRC on the strip and carefully screwed it down, then wiped the PRC down until it was just a very small amount of the PRC showing.  

Interestingly I never saw any Tinnermans, it was just screws into sheet metal.