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New SB issued May 6 (not so lucky)

agirard7a

agirard7a

Well Known Member
mkubyv.jpg


I checked my RV-3 today (circa 1985 or A wing)
1010 hrs AF. I sent the photo to Vans. Seems I may
Be "on my own" with a fix due to the age of the wing.
I came up with a plan or a fix with the assumption of the crack
accuring from a point load issue from the aileron attach point.
A fellow RVer/accomplished engineer, assures me this crack is not a point load issue but due to flex of the wing. Thus my point load fix is out the window.

Hopefully Vans will give a suggested fix.
 
Are you sure it's a crack and not a cobweb? (I am referring to what looks like a long crack on the right side of the picture running vertically about half way up)
 
Last edited:
Crack

Sorry, forgot to point out, I am referring to the horizontal (ish)
Crack under the right nut plate.
 
Albit-

Is the shop head missing on the rib/rear spar flange middle rivet??? Get Billy at KPYM to fix this for ya:D
 
Missing rivet.

Hi Mike. Yes appears to be the case. The least of my
Concerns compared to the apparent crack below the
Nut plate. Hopefully see you at KOSH provided I can fix this in time!
 
agirard7a said:
I checked my RV-3 today (circa 1985 or A wing)
1010 hrs AF. I sent the photo to Vans. Seems I may
Be "on my own" with a fix due to the age of the wing.
I came up with a plan or a fix with the assumption of the crack
accuring from a point load issue from the aileron attach point.
A fellow RVer/accomplished engineer, assures me this crack is not a point load issue but due to flex of the wing. Thus my point load fix is out the window.

Hopefully Vans will give a suggested fix.
Click to expand...

You and the engineer should rethink this conclusion. Cracks typically will begin and propagate 90 deg to the major stress direction. That would be parallel to the bottom flange of the spar. This looks like flexure aggravated by the sharp steel edge of the nut plate. Regardless, a discussion with Vans is in order.

Yes, stress guys, I know there are other failure modes in complex stress fields for complex materials, but that truly does not seem to be the case here.
 
Last edited:
BillL said:
You and the engineer should rethink this conclusion.
Click to expand...

I agree.

The crack is likely caused by the same loads that are in play, and the reason for, the SB.

It is the vertical loads (up, and down) being applied and released in many cycles, to the hinge bracket when the aileron deflects up and down.
 
Albit, Mitch spotted something up with the flange center rivet. Is that shop head snapped off or is the rivet missing entirely?

:( CJ
 
Crack

Crack visualized from bottom flange to aileron cut out....very little structure remaining. ****! 86 RV4 I built. just shy of 1200 hours. lots of 3-4g aerobatics...and stopped doing snaps probably 15 years ago except as slow speed spin entries...always used gust locks. Very sad just now.

Thank you DR for this forum. I found this condition because of the SB notice here. Happy to find it with a flashlight instead of a folding wing....J
 
My Rv-4 with 906 hrs was crack free.. If I had found cracks, I would be real tempted to just cut a circular or square access panels in front of the spar on the bottom skin to allow easy access to put in the doubters.
 
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