RV-12 Tie Down

[ben barron]

I (unfortunately) drilled out the 3/8" hole on the top of the wing for the tie up and was wondering what others have done to cover it up (so water... does not get in the wing) while not (if ever) in use?

[MartySantic]

An aluminum or plastic hole cover from your hardware store? Could even paint it.

[RFSchaller]

Not a big deal. My Cherokee has a plug on each wing to gain access to the landing gear strut charging valve. Each has a small cap that pops out to get to the Schrader valve.

Since you have the hole you may as well tap it in case you want to use it as a lifting point later.

[DaveWelch]

Check the plans, I believe those are tapped for fine threads, 24 vs 18 as I recall.

[Gagarin737]

You can use the HW-00003 plastic caps used at the 3/8 holes near the gear:

[WingedFrog]

Originally Posted by Gagarin737

You can use the HW-00003 plastic caps used at the 3/8 holes near the gear:

Very crafty, Joery! I had the same thought but gave-up explaining what it was and where it was. Your picture saved the day!
Who said "a good picture is better than a long speech"?

[Charlie12]

The KAI says jacking the plane at the wing tiedowns is OK. If you can jack it you can lift it. It's the same applied loads and the same supporting structure. It would make me feel uncomfortable to see it lifted this way---I guess I need to see safety nets. But I taught structural design for many years and the textbook answer is that it should work.

[RFSchaller]

Charlie, you're logic seems sound, but if the threads pull out lifting the plane any substantial distance the consequences seem worse than if the threads collapse under compression from jacking because the threaded Jack rod will bottom out against the portion of the tie down block that has not been final drilled for tapping.

Rich

[Charlie12]

I agree. That's the kind of safety net that I would prefer to see.

But on a 3/8 bolt the area that would have to fail in shear to pull out the threads is pretty big. A few hundred pounds tension on whatever fastener is threaded in should not be any real threat even with aluminum threads.

Last year I asked someone at Van's about why I was instructed to bother tapping the top of the fitting. The answer was that there was once a concept floating around to use the top of the fitting as a lift ring to create a device to assist with solo installation of the wings. The idea faded away but I kind of like it.

[RFSchaller]

Charlie,

I agree it's unlikely the threads would pull out, but that's little consolation if it happens. I once attended a lecture on risk. It was defined as probability times consequences. Extremely low probability times unacceptable consequences produces high risk! 😱

Rich