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insightmfgsystems

I'm New Here
Don't know where to post this so here it is...

So I picked up wings and empinage -4 75%complete....Construction is rough (payed almost nothing and I enjoy resurecting what could otherwise become scrap metal,,Also like to manage risk by investing minimal until probability of follow through is higher,,,,(Denial stage) but really, I observed all these issues before I took it on and had a reasonable solution formulated for each issue..Any input will be extremely appreciated...

Some of the issues..
1. no primer anywhere;(

2. literally 60% rivets barely hit and many that where too long and rolled sideways etc. (this one is the hardest for me to comprehend the WHY)

3. half of the RIB flanges where cut off,,,,,Really?
(this one is second hardest for me to figure out the why)

4.one wing is closed up and I will deal with that one later,,,the other wing half was jigged and all drilling was done,,,Those DRILLED skins are MIA and with what I baught came completely new set of UNDRILLED skins for that wing... so unless I buy or fab new ribs I am backdrilling from the inside..

5.Right wing spar (at roughly the center of 406g (root most doubler)) has one rivet that was drilled out and drill went off track so,,, what is acceptable oversize for this 3/16" rivet?..looks like I will have to open it up to .236 to get a clean hole..is there a metric rivet? Or I could turn a 1/4" rivet down..Most inportant though is that it is not already too large and going to compromise integrity..[/B]

6. Aside from the lack of primer, the controll surfaces and empinage all look good as though they where built by a different person....

I'm guessing this post will open up a can of worms but hey,,,,thats part of the fun...
 
You could...

insightmfgsystems said:
Don't know where to post this so here it is...

....
4.one wing is closed up and I will deal with that one later,,,the other wing half was jigged and all drilling was done,,,Those DRILLED skins are MIA and with what I baught came completely new set of UNDRILLED skins for that wing... so unless I buy or fab new ribs I am backdrilling from the inside..

5.Right wing spar (at roughly the center of 406g (root most doubler)) has one rivet that was drilled out and drill went off track so,,, what is acceptable oversize for this 3/16" rivet?..looks like I will have to open it up to .236 to get a clean hole..is there a metric rivet? Or I could turn a 1/4" rivet down..Most inportant though is that it is not already too large and going to compromise integrity..[/B]
.....
Click to expand...

...do what some early builders did and use a sheet of thick mylar drafting paper, tape it in place of the skin and trace the rivet locations. then use the mylar as a drilling template.

On the spar, could an AN4 bolt in a carefully reamed hole be a substitute? Check with Vans first...
 
I suppose a bolt would work although I like the tighter fit of a rivet..better fatigue properties..But yes i will check with VANS on the hole diameter..

The mylar sounds good in conjunction..

thank you
 
Backdrilling the ribs should work fine. Make sure the wing is properly and solidly held in the fixture. Put the top (or bottom) skin in place and backdrill. Remove that drilled skin and put the other in place and backdrill.
 
WARNING!!! On the spar hole drill question

insightmfgsystems said:
5.Right wing spar (at roughly the center of 406g (root most doubler)) has one rivet that was drilled out and drill went off track so,,, what is acceptable oversize for this 3/16" rivet?..looks like I will have to open it up to .236 to get a clean hole..is there a metric rivet? Or I could turn a 1/4" rivet down..Most inportant though is that it is not already too large and going to compromise integrity..[/B]
Click to expand...

I think there are oversize "repair" rivets available in 1/64" oversize diameters. Standard AN470's run in 1/32" diameter increments so the next size up would be 7/32" which is .032" larger in diameter, but if possible just replace it with another .187" rivet and allow the new one to fill the hole without drilling it larger. The idea here is minimal enlargement of the hole to make the repair.

I definitely wouldn't advise to enlarge the hole to .250, because doing so will compromise the structure. The area you describe - if I understand correctly - is a stress critical area for the spar. I wouldn't bet there's a huge amount of margin in the structure there.

The reason the hole cannot be significantly oversized is because the spar components are designed to react bending loads and must remain under their max tensile stress limits under worst case conditions. Since tensile loads cannot pass through holes, drilling the hole bigger effectively reduces the cross sectional area of the tensile members in the spar and will result in a compromised structure.
 
Not quite in this case (possibly)...

Bill Wightman said:
I think there are oversize "repair" rivets available in 1/64" oversize diameters. Standard AN470's run in 1/32" diameter increments so the next size up would be 7/32" which is .032" larger in diameter, but if possible just replace it with another .187" rivet and allow the new one to fill the hole without drilling it larger. The idea here is minimal enlargement of the hole to make the repair.

I definitely wouldn't advise to enlarge the hole to .250, because doing so will compromise the structure. The area you describe - if I understand correctly - is a stress critical area for the spar. I wouldn't bet there's a huge amount of margin in the structure there.

The reason the hole cannot be significantly oversized is because the spar components are designed to react bending loads and must remain under their max tensile stress limits under worst case conditions. Since tensile loads cannot pass through holes, drilling the hole bigger effectively reduces the cross sectional area of the tensile members in the spar and will result in a compromised structure.
Click to expand...

The center of the 406G part (if it's the lower spar cap - the one in tension) on the -6 models is exactly were the holes are drilled out to 1/4 inch for AN4 bolts for the -6A gear mounts.

Again, check with Vans...
 
thanks for all the feedback..

Vans responded on the bolt size and suggested I round up and use the 1/4" rivet.. Stating also that the further inboard wing joining holes are larger even yet.. (Definately room for debate as to weather those holes see the same type of loads being that they have thick steel plates sandwiching them), ,,It will take opening it up to .23 to get a clean hole so I think will likely turn a rivet to whatever the hole cleans up to..


On the back drilling, seems pretty straight foreward as long as I can slowly peel back the skins on the first side done while backdrilling/cleacoing the second side.. so that the structure stays put..I will definately post the progress of that one so that others in a similar situation can observe the ride..

I live in dry Northern Nevada and aside from resale value What is the consensus on having zero primer?
 
I must have the wrong idea of where this hole is, but the steel plates in the center section of the RV4 are the stuff of bridge building...
 
no primer no problem. you are not 10 miles from the ocean, it will be fine. (corrosion wise)
 
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