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Oblong Holes -- HS-609PP to HS-603PP (rear spar)

Golf Echo

Golf Echo

Active Member
Help! I'm kinda freaking out here... :eek:

I have match-drilled the left and right side HS skins to their respective substructures. Next, the book has you deburr all the holes. In deburring the holes on the rear spar, I noticed something horrible: oblong holes. :(

I used a #30 fluted reamer when I match-drilled HS-609PP to HS-603PP. I also used my 6000rpm Sioux drill. In doing some searching and reading of past posts, it now sounds like this was a REALLY bad combination. :mad:

In any event, I can't talk to Van's until Monday (which I am certainly planning on doing for a definitive answer). In the mean time, I'm hoping to get some guidance from the wealth of experience and knowledge on VAF.

Am I going to have to scrap the HS-609PPs and HS-603PPs and go shopping at Van's house of replacement parts?

Here's the evidence:

IMG_0144.JPG


This one looks REALLY bad. This is definitely the worst of it, and perhaps it looks worse in the photo than in person. :confused:
IMG_0147.JPG


Thanks in advance :eek:
 
Some more info...

I see that the Mil Spec (MIL-R-47196A) has a table for maximum diameter limits. I'm not sure if this applies to oblong holes or not...

Anyways, it gives the maximum hole diameter for an AD4 rivet as 0.135".

I measured the holes with my digital calipers, and counted how many holes were larger than 0.135" in the longest dimension of the elliptical hole.
On the right side HS-603PP - 11 of 54 holes were over.
On the left side HS-603PP - 25 of 54 holes were over. :eek:

Most of the 'overs' were around 0.136" - 0.138". A couple were as large as 0.144" :(

For now, I think I'll have a carbonated adult beverage and call it a night... ugh.
 
No need to sweat... lots of options to fix this guy.

One serving suggestion:
1. Shoot -4 rivets into all holes <= .135" diameter
2. Drill all other holes up to .143-.146" (#27)
3. Install correct grip CherryMax CR3243 -4 oversize rivets into remaining holes

The CR3243 (available at Spruce) is a 1/8" oversize blind rivet that is usually accepted in certified applications as a direct replacement for a -4 solid rivet. The maximum allowable hole diameter is .146". You can probably set them with your hand puller, but the $39 pneumatic rivet puller for Harbor Freight is so much easier with these larger rivets.

Take care,
David
 
Cherrys are a great suggestion. Its also possible to pre-squeeze a rivet to make it slightly fatter to take up the slack. If you have to there is always the option of going to a -5 rivet (use a 3X gun and large bar with two people).

Pete
 
Solid oversize

I personally aviod cherrys. Here is the P.N for oversize solid, think the other "oops" rivet, NAS1242AD universal head and NAS1241AD countersunk.
http://www.gen-aircraft-hardware.com/images/pdf/solid_rivets_Oversize.pdf
It's hard to see without a rivet in the hole, but I might be inclined to see if a standard rivet, maybe a half size longer, would go. Just get it to fill up the hole once it's set.
Cherrys are "riskier" to remove if you have problems, and most any DER will tell you to avoid mixing up the type of fasteners in a line because how they flex (or not) differently.
 
Andrew M said:
I personally aviod cherrys. Here is the P.N for oversize solid, think the other "oops" rivet, NAS1242AD universal head and NAS1241AD countersunk.
http://www.gen-aircraft-hardware.com/images/pdf/solid_rivets_Oversize.pdf
It's hard to see without a rivet in the hole, but I might be inclined to see if a standard rivet, maybe a half size longer, would go. Just get it to fill up the hole once it's set.
Cherrys are "riskier" to remove if you have problems, and most any DER will tell you to avoid mixing up the type of fasteners in a line because how they flex (or not) differently.
Click to expand...

Agree with Andrew, fill the ones that are in limits with -4's, step up the rest to either the OS rivet or -5's.
 
obong holes

I would buy a new rear spar for $22 and make sure the spar doubler is fully rounded to nest into the bend all the way.
 
Taildrgr said:
I would buy a new rear spar for $22 and make sure the spar doubler is fully rounded to nest into the bend all the way.
Click to expand...

Good thought!

I had rounded the HS-609PPs thoroughly before match-drilling, but when I clecoed them on to match-drill, I accidentally swapped the top and bottom HS-609PP. So, the rounded edges weren't where they were supposed to be. That definitely couldn't have helped.

I'd need to replace both HS-609PPs and both HS-603PPs, so the part bill would be closer to $200. I might just get them to throw the parts in with my wing kit...
 
oblong holes

Don't think I'd use cherrymax rivets on a spar...imho...having been an a&p for 34 years i've seen these fastners loosen over time. We used them only as temporary repairs until permanent repairs could be made. Blind installations required cherrymax rivets or huck bolts . If I were building spars in your situation I'd use a piloted reamer to clear up the holes,especially on a spar. Start with a 1st over and see where you end up. If the new part is cheap just replace it and match ream,not drill the holes.
 
Andrew M said:
I personally aviod cherrys. Here is the P.N for oversize solid, think the other "oops" rivet, NAS1242AD universal head and NAS1241AD countersunk.
http://www.gen-aircraft-hardware.com/images/pdf/solid_rivets_Oversize.pdf
It's hard to see without a rivet in the hole, but I might be inclined to see if a standard rivet, maybe a half size longer, would go. Just get it to fill up the hole once it's set.
Cherrys are "riskier" to remove if you have problems, and most any DER will tell you to avoid mixing up the type of fasteners in a line because how they flex (or not) differently.
Click to expand...

Walt said:
Agree with Andrew, fill the ones that are in limits with -4's, step up the rest to either the OS rivet or -5's.
Click to expand...

Guys,

Do you have a suggestion on where to source the NAS1242AD4 rivets? I can't find them on the Van's site or at Aircraft Spruce. :confused:

Thanks.
 
oblong holes

Just for my 2 cents, I don't know how you used your reamer, but I have found that you get better results when pulling the reamer through the hole rather than trying to force it through like a drill bit.

Ed Booth
 
Update...

Thanks everyone for your input and suggestions thus far.

I spoke with Van's... They aren't very keen on me using NAS1242AD rivets as a fix based on the number of NAS rivets that would be required, and the corresponding number of under-sized heads.

They are suggesting either stepping up to AD5 rivets or replacing the parts. At this point I'm leaning towards at least giving it a go with the AD5 rivets, and seeing how things work out. I'd probably end up re-drilling and using AD5s in most of the 603pp to 609pp attach holes. If it all goes sideways, I can always order the new parts.

Of course, I'll need to buy a 5/32" cup set as I don't already have one. I'm thinking a 5/32" cup set and the 12" back-riveting set from Cleaveland would let me set these rivets using my 3x rivet gun and c-frame with hopefully excellent results. Anybody have experience with using this setup to shoot AD5 rivets?
 
Last edited:
Golf Echo said:
Of course, I'll need to buy a 5/16" cup set as I don't already have one. I'm thinking a 5/16" cup set and the 12" back-riveting set from Cleaveland would let me set these rivets using my 3x rivet gun and c-frame with hopefully excellent results. Anybody have experience with using this setup to shoot AD5 rivets?
Click to expand...

I think/hope you mean 5/32". No reason to get too carried away.
 
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