What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Need Advice -- Drilled into Spar

Careful who you ask...

My point, which I tried to highlight- was that in this given dilemma, a TC opinion won't give the OP a definitive answer as to whether proceed or to repair. That can only come from Van's.
Click to expand...

Along this same line, not everyone at Van's is an engineer. There is Van himself, then the fella who replaced Ken Krueger and not sure about the rest.
When you do ask for advice about this matter try get it from the right person. Most everyone else has built an RV but that only makes him the same as some of us... I live fairly close and have gotten way diff advice from diff folks on the same day. No surprise...Some will say "build on", others "let me talk to Van"...
Love those guys, but...
 
aerhed said:
Okay, for you guys that like to calculate stress & strain: What would be the effect of installing an "extra" rivet in a spar cap?
Click to expand...

That depends hugely upon its location and the specific geometry there. The effect could range from having a slight increase in strength to a major loss of strength or fatigue life. Each case must be considered upon its merits.

Although if enough people were to install an "extra" rivet, I'd expect Van's to issue some guidelines or create a process that would help the builder avoid doing that.

Dave
 
tkatc said:
No word yet?
Click to expand...

Rian is the engineer at Van's who will do the analysis. He had told me it would be several weeks before he could get to it, but I was getting anxious (imagine that) and sent him a note the other day. He responded saying that he has another request with spar damage very similar to mine and that he plans to get to them both late next week or the following week -- been very busy lately, and I'd imagine the holidays haven't helped from a business perspective. As much as I would like an answer RIGHT NOW :rolleyes:, I'll just have to be patient!

The engineer in me wants to do the eval on my own, but I'm only HALF an aeronautical engineer -- changed to mechanical mid stream due to the job market, so while I may have some of the ability, I don't have the credentials, plus in my opinion the evaluation must come from Van's. At least I've been able to do some research on the problem while waiting. Plus, I'm still working on the right wing and have plenty of work to do.

I will post their finding once I have one. I'm not the only builder that's done this, nor will I be the last, so might as well share the experience.
 
You should be ok. Feather the edges a little and prime or Alodine the hole. But check with Van's to be sure.
 
Still No Answer

Well, problem reported to Van's 12/10/12, and it's now 1/9/13 -- still waiting for an answer. I've stopped my build until I hear something.
 
Got An Answer

Rian sent me this response today:

"The good news is you drilled in between rivets. Looking at the stresses in the spar in this area you will be ok but for the sake of fatigue I would like to remove the drill point.

Find a large diameter ball end mill type cutter (borrow one from a local machine shop if you do not have one).

Set up the spar in a drill press. Set the depth of the drill press so you will not be cutting any deeper than the existing drill point.

Remove the drill point with the ball type cutter. The larger the diameter cutter the better but do not go so large as to get near the area below the rivets on each side. I would go no larger than a .500 inch DIAMETER ball cutter if going 1/16 deep. If you go deeper use a smaller diameter cutter.

Smooth the edges of the hole left by the cutter...again do not remove so much material as to remove material below the area of a rivet in the spar which will reduce the cross section of the spar at a rivet location."

I then asked about any affect on the aircraft rating, i.e. +6/-3g. This was his reply:

"If fixed as prescribed you will have no change in the rating."

Well, I'm lucky if nothing else! Now to figure out how to mount a drill press over the spar and make this repair without causing a bigger problem.

One other comment: I'm posting this to let you know Van's response to my problem, and that is what it is, their response to my problem. Even if you have a similar situation, do not assume this fix is for your situation -- you must contact Van's for that evaluation.

I appreciate everyone's kind words of encouragement and ideas regarding how to take care of this. It's been a long month!
 
I would NOT put a endmill in drill press! Chances are it will chatter and you'll have worse problem. A manual vertical mill would be a better option. Or you might have to blend it out by hand with dremel or something.
 
how to

Duplicate the "damage" in a piece of scrap. Chuck up the drill bit that made the damage and use it to line up precisely where the damage is, then clamp down. One end of the piece being cut should be resting against the vertical support of the drill press in the direction of rotation. This keeps the clamps from being loaded when it wants to twist. Swap to the ball end mill and go to town. Cutting speed pressure, and lube will determine how smooth it is. (fast and hard???) Get all this figured out, and build confidence on scrap.
I use a drill press as a vertical lathe or as a mill on simple tasks routinely.

Good Luck!
 
Good Results on Scrap

Actually duplicated the problem on some scrap last night and used a 1/2" ball end carbide burr and my variable speed hand drill. Worked very smooth with no chatter and no wandering since he burr has small, close teeth. Got very good results. I'll duplicate it again few times on scrap before proceeding.
 
Hey Jim,

Glad for you to hear a fix is possible!!!

One doesn't want to have to replace a $par... :eek:

Cheers
 
Glad you finally have a solution. Now the big question lies ahead....do you prime the repaired area or not? :eek::eek::eek::D
 
Spar Prime

Yep. That was actually at the end of Rian's reply, but I left it out when I grabbed the text. I plan to spot prime like I did with the spar countersinks.
 
You were asking about a drill press. If you taped up the area for protection and clamped a suitable steel plate, you could use a magnetic clamping drill press. With mine you could clamp the base of the drill for extra security. You probably don't have one but a rental shop should.
 
Done

Repair completed. Time to move on -- FINALLY! Used 3/8 four flute cutter, then smoothed with 3/8 carbide burr sitting on a small square of maroon Scotchbrite, then hand polished with 600 wet/dry sandpaper, and finally Dremel buffed with polishing compound.



Uploaded with ImageShack.us
 
Thanks

Thanks, everyone, I am very glad to have this "opportunity" behind me. I did learn a lot from it, including what's involved in resolving a mistake this severe in the build. In the end I was very fortunate that my drill point was located between the spar cap rivets -- this could easily have had a different outcome. Here's to hoping that none of us have many of these types of issues in our futures! ;)

Thanks again to everyone for the great advice and support. Once again VAF comes through!

Jim
 
Stalldog said:
Thanks, everyone, I am very glad to have this "opportunity" behind me. I did learn a lot from it, including what's involved in resolving a mistake this severe in the build. In the end I was very fortunate that my drill point was located between the spar cap rivets -- this could easily have had a different outcome. Here's to hoping that none of us have many of these types of issues in our futures! ;)

Thanks again to everyone for the great advice and support. Once again VAF comes through!

Jim
Click to expand...

Great job Jim - Now, delegate those drill stops to the back of your tool box drawer. There is (arguably) a time and a place for them but your not the first person to get lulled into a sense of security just to find they slipped or loosened.
 
You must log in or register to reply here.
Back
Top