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Drain Holes

Roger Peterson

Registered User
Sweeny, Texas
For years I put drain holes in the elevators, but never in the Horizontal Stabilizers. Why put them in either one, they are both sealed.
What do the rest of you do.
 
...fill them with nitrogen and plug them. .......or helium...

At least down here condensation would be clean water. If I put drain holes in them, the air has salt in it.
I have never put drain holes in the Horizontal Stabs and never noticed them filling with condensation. It is always in a open hanger, and this part of Texas don't have large temp swings.
Just trying to work through this. The Nitrogen might be the answer.
 
It's not perfectly sealed - if it were the surfaces would puff up and suck in with changes of altitude and temperature. Thus nitrogen would migrate out just as easily as water vapor can migrate in. But - if it's just breathing vapor in and out I wouldn't think condensation would be any worse with or without drain holes?? That would be consistent with your experience of no problems - -
 
Speaking of this Roger... does anyone put holes and then inject their engine mount tubes with Tubeseal or similar and then plug, similar to fuselage tubes. And if so.. what is the cc to inch of tube used?
 
It's not perfectly sealed - if it were the surfaces would puff up and suck in with changes of altitude and temperature. Thus nitrogen would migrate out just as easily as water vapor can migrate in. But - if it's just breathing vapor in and out I wouldn't think condensation would be any worse with or without drain holes?? That would be consistent with your experience of no problems - -

I think we all have seen an insulated glass window that the seal slightly failed and turned the glass milky looking. Airflow is important, when a somewhat sealed area cools it draws in air and any mosture in it into the semisealed area. When it warms it expands and pushes out the air but leaves some of the moisture behind. It's just like the lift struts, open ended or totally sealed.



Glenn
 
Thanks Mike.. never even thought to look! Anyone ever see enough engine mount internal rust to bother?????
 
Aircraft with 60 years of flying most here have cracks repaired but, no internal known corrosion, that I have seen.

These planes get salt spray too. Engine mounts are the 7th wonder.
 
Did an annual on a Citabria a couple of years ago that was covered with no drain holes in the horizontal stab. Some of the tapes were poorly sealed and I could hear water sloshing around inside the stab and was finding tiny water seeps at the back of the stabs. I poked holes everywhere there should have been a drain hole. I couldn't believe the amount of water that drained out. Of course the stabs had to be replaced as the tubing was rotted out from holding water in there for a few years.

-CubBuilder
 
I take a cheap soldering iron, turn the tip around, and only leave about 5/16" exposed. The flat end burns more concentric holes than the pointy end.

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Having a short flat tip exposed keeps you from poking all the way through to the top fabric in areas like the TE of the flight controls.

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Also when using the flat end you can move the hole farther back closer to the center line of the tube. If you have a 1/4" tapered point on your and you stick it through the fabric too close to the tube when the point hits the tube, the iron slides forward, and end up with an oval or slot. I find it's easier to keep small and concentric holes when you use the flat end. You will need to wipe the residue off the tip about every 4-5 holes to keep it burning cleanly through. I prefer not to use any grommets. I burn the holes where there are 2 layers of fabric and I do it just before I paint to the top coat color.

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Jason
 

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I put holes in mine with the soldering gun like Jason and they have a nice clean look to them.
 
Same as Jason, but take it one more step. With a sharpened pencil (use a sharpener, not your pocket knife); burn the hole, then stick the pencil in it and spin. It makes the hole perfectly symmetrical and pulls any slag out as well. Makes for a very nice finished look.

nkh
 
Anything welded or "sealed" can leak. That is why the FAA, USCG, etc require fuel tanks to be pressure tested before service. Drain holes are counter intuitive but make me feel better under the conditions and maintenance available to me and the aircraft available to me. I seal my drain holes with some 3M tape and inspect when condition may let water in by removing the tape. I spray ACF-50 into the holes about every one or two annuals.

Inspection and drainage are paramount with 4130 tail sections! Be careful out there!
 
For years I put drain holes in the elevators, but never in the Horizontal Stabilizers. Why put them in either one, they are both sealed.
What do the rest of you do.

I put drain holes in mine. I seem to put too many rock holes in my stabs to keep them tight.

I also used the soldering iron tip to put in all my drain holes. I've also used seaplane grommets on an earlier project. BTW, seaplane grommets work well when running wiring to the rudder. I point them backwards and down at 45º and run the wiring through it.

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