RTV and STIFFENERS

mattsmith · #1 08-02-2009, 06:28 PM

So I have closed up one elevator and 1/2 the rudder and remembered that I am suppose to put RTV on the aft end of the stiffeners. so my question is how important is the RTV? I really don't want to drill all those rivets. any help would be appreciated.

Mel · #2 08-02-2009, 07:24 PM

My -6 has been flying for over 16 years with no RTV. No cracks yet.
If the trailing edge radius are formed properly, you shouldn't need it.

jeffrj2007 · #3 08-02-2009, 07:25 PM

I dont know if this makes you feel better but I know two builders that left out the RTV and both ships have 400+ hours and no proublems?. If you have not finished the forward overlap you can drill small holes and ese a tube to inject a small amount of fome at the end of the stiffners. I have seen this done also.

rv7charlie · #4 08-04-2009, 08:40 PM

It's been a long time, but IIRC, I added RTV after building by using 1/4" tubing (tygon?).

I found that I could get the end of the tube near the ends of the stiffeners on every bay using various paths. On one of the control surfaces, it went straight in from each end.

(Experiment away from the plane first.)

Hold the end of the tubing over the RTV tube & force several inches of RTV into the tube.

Position the loaded end where you want the RTV.

Use carefully controlled air pressure to slowly push the RTV out of the tube.

Charlie

roee · #5 08-04-2009, 09:01 PM

FWIW, I asked Van's about this way back when. They told me that cracking was an issue many years ago, but they went to thicker skins on the elevators at some point and they suspect that gooping up the trailing edges (with RTV, proseal, whatever) should no longer be necessary. They said the recommendation in the manual is pretty much just a relic from the early days with the thinner skins, but it's still recommended "only as a precaution".

I see only two reasons to not goop it up. 1. The goop may come loose in the future and cause problems. And 2) the added weight (it's not just the weight of the goop itself, but also the corresponding extra weight in the counterbalance arm).

For no particularly good reason I ended up using proseal in one of my elevators and nothing in the other. I'm not flying yet, so nothing to report. I guess we'll see in a few years.