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Old 03-07-2017, 03:14 PM
gonzaviador gonzaviador is offline
Join Date: Jun 2015
Location: Santiago, Chile
Posts: 6
Default Wrong countersink

Hi guys. Once again I'm looking for your wisdom because I made a mistake.

The mistake I made was while fitting the right side skin to the center section of the fuselage in preparation for riveting. I didnít recall that the F-704H was flat on the inside and by mistake countersunk the holes of the rivets (the -3 ones) of the vertical "legs" of the F-704C and D of the right side.

Is acceptable to carry on or should I replace both F-704C and D?

Maybe I could use -4 rivets (Ups rivets) instead the original -3... Or add a strip of aluminum behind the whole structure... or both...

Please advice...

Thanks a lot!
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Old 03-08-2017, 10:08 AM
jmjula's Avatar
jmjula jmjula is offline
Join Date: Oct 2005
Location: Portland, OR
Posts: 173

Without a picture I can't really tell where your mistake is, been too long, but that structure will have some of the highest stresses in the entire airplane so you don't want to compromise strength in any way. You definitely should ask Van's on this one...
James Jula - CFI/II/MEI - N713JL RV-7A First Flight 10/12/15 - "What is chiefly needed is skill rather than machinery." Wilbur Wright, 1902
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Old 03-08-2017, 10:32 AM
nilberg nilberg is offline
Join Date: Dec 2012
Location: Katy, TX
Posts: 134

I think I know what you mean. You countersunk the "golden legs" (F-704C and F-705D) instead of the center section side plate (F-704H) that goes between the 705 and skin.

I agree with jmjula, this is a case for Vans support. There is lot's of load transfer going on in that area from wings to fuselage.

The F-704C and F-705D are match drilled to the spar and have high tolerance bolts going through them. It could be that it is acceptable to replace them, but drilling out rivets from that section is risky.

Another Option:
You definitely need to fill the countersinks and the F-704H is too thick (0.063) to dimple. Ask Vans if you can replace F-704H with 0.040 + 0.025, match drill and dimple both. 4 layers of dimples might not be OK in that area either. Riveting also get difficult as there is too much flexibility (the conical bend has a few 4-layers and those were a PITA to get right).

Vans support knows best, I wouldn't do anything before getting their approval in this case.
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