need to pick a 'fix' technique

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tmbg
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need to pick a 'fix' technique

Post by tmbg »

On my right elevator skin, I had a couple stiffener rivets that didn't want to set well down near the TE, and I drilled them out a couple times before deciding to use pop-rivets.

Unfortunately, they're oversized holes now... the TE is already bent, and I tried bucking oops rivets in there, but there's not enough space and I creased the skin a bit with a slipped bar. I don't have any blind rivets that are countersunk -42. I have some countersunk -44, but they're WAY too long, and would interfere with the rivet heads on the other side of the skin.

I have two options as I see it: wait until I can get ahold of some short-grip -4 flush blind rivets, or make some little squares of 0.025 or so alclad with #40 dimpled holes and back up the #30 holes and pull CCC-32's through the assembly.

if I choose option A, is there any reason why I couldn't go ahead and finish the elevator, then pull those last couple rivets after the fact?

if I choose option B, is there any issue with the fact that the holes in the skin and stiffener are oversized? Seems like the loads on those couple rivets probably aren't excessive, and any loads there are will be in tension rather than in shear. There's three adjacent stiffeners with the very aft hole that need filling, and one of them also has the second to aft hole that needs filling.
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
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cjensen
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Post by cjensen »

I'd choose option A and move on. I wouldn't add weight to the TE of the elevator with .025 doublers. You can pull the blinds anytime down the road, just make note so you don't forget about it.
Chad Jensen
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tmbg
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Post by tmbg »

sounds reasonable.

The only other thing that bugs me is the grip length... I'm not in front of the s tuff, but I believe the skins are 0.020 and the stiffeners are 0.025 or 0.032. So I'm dealing with 0.045 or 0.052 of material.

That tells me that I'd want to use a -41 rivet, which is 1/8" shank, 0.062" grip length.

I dunno how to go about picking rivet material, other than strength, but I guess the ideal would be something like a BSC-41 (aluminum, steel mandrel, flush, 1/8 x 0.062)

Unfortunately, spruce doesn't have any kind of flush -41 listed. The smallest flush rivet they have is a -42. They have xxP-41 protruding head rivets though! However, I have those already! (AD-41). I don't really want protruding head rivets on the top surface of my elevator!

I guess I'll get the BSC-42 and/or CCC-42. Hopefully they'll pull up tight without any interference below.

I have run out of the MK319BS rivets that came with my empennage kit, and I bought some CCC-32 rivets from spruce to replace them. They're reasonably close... the MK319s I think are slightly oversize, and I always had to use some force to insert them into the holes, whereas the CCC-32s seem to fit a bit closer without pressure.

Unfortunately,
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!

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TomNativeNewYorker
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Post by TomNativeNewYorker »

CR3242-4-2 is an oversized countersunk cherrymax rivet. I use them often here at work. Want some, I'm in Marietta, maybe we can work something out. I work evening shift on the Naval Air Station.

tmbg
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Post by tmbg »

that'd be fantastic... I need about six. I live in kennesaw, and I could probably meet you somewheres sometime, although I'm home in the evenings when you're likely to be at work. What works for you?
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!

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TomNativeNewYorker
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Post by TomNativeNewYorker »

Probaby this weekend will work. I should be off, and can buzz up towards the mall on Barrett Pky. Give me a call (I''ll IM my cell#) and we can figure something out. Any other rivets, let me know, and I can see what I can scrounge up at work, and may possibly have a grab bag as well.

tmbg
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Post by tmbg »

sounds good... I really appreciate it!

I don't know what else I might need going forward, but a grab bag sounds mighty handy!
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!

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TomNativeNewYorker
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Post by TomNativeNewYorker »

If you want that stuff I collected for you this weekend, let me know. I am going out of town Monday for a week. When I get back, will only be around for a short and busy week getting ready to go out of the country for an extended period.

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