K

kthom_441

Member
Working on the left wing of my RV-9 (soon to be an A) and just made my first mistake. OK, maybe not my first, but this needs to be repaired.

While drilling the left spar for nutplates and other holes, I drilled the pitot tube hole as shown on the drawing. Now that I'm thinking more clearly, I'm realizing that I need a completely different mount since I will be using a heated pitot. As a result, I have a too-large hole in the spar. Fortunately, I didn't drill the leading edge skin to match.

So the question, how do I repair, patch or otherwise make a large hole smaller?

-Ken
180 hours and about ready to rivet the top skins.
 
If you drilled the spar to the plans why do you have to repair it? Do you need that area for the heated mount?
 
I'm trying to envision the hole you drilled. Was it in the spar web? Probably a 1/2" hole or thereabouts? If the hole for your new pitot probe doesn't violate edge distance requirements from the one you already drilled, I'd just deburr the original hole and move on.

A picture or a more detailed description might be helpful.
 
I don't think I would worry about it from a strength perspective, as already pointed out this hole would be there if you were using the stock pitot. However, it does create an issue for the skin to spar rivet in that location. I suggest you cut a round plug of 1/16" aluminum to fit in the hole. Also cut a small rectangular strap 1/32" to 1/16" thick to go on the inside of the spar flange. Make this long enough to pick up the rivet on each side of the 7/16" hole. The strap prevents the plug from working loose after the skin is riveted on. JB Weld or epoxy both parts in place to make it easier to rivet the skins later on and remember to use longer rivets in these locations.

I used the SafeAir mast for my heated pitot, as mentioned above it picks up the 3 aft/outboard rivets in this wing bay. On the mast, the three forward rivets pick up the spar and the aft rivets only pick up the skin. I made a transverse stiffener for the rear of the mast plate out of Van's J-stiffener and riveted this to the skin from the inboard to outboard ribs in that bay.
 
I did exactly what you did - and I plugged the hole with my OAT sensor. It's gotta go somewhere, might as well hang it out in the wind and fill the hole.
 
Not knowing the engineering data behind this, I would be inclined to contact Van's and ask their opinion. Normally the hole has an AN fitting in it which may (or may not) act to reinforce the hole, I'm not sure.

After all we are talking about the SPAR, so why not get Van's engineering to bless it then you won't have to worry about it :D
 
Good inputs

Thanks for all the comments. I ended up patching the hole as Bill did in his photos. A filler and then a backer with JBWeld to hold it all together for now. Eventually there will be rivets.

I like the idea of the OAT but decided I want to place it closer to the fuselage. Also lets me delay making the final location decision until later.

Thanks again!

-ken
 
You must log in or register to reply here.