Seeking advice RV3b annual condition inspection

[Richard RG]

Tragically, another RV3a has recently gone down. Though my RV3 is the B model having the structural upgrades to address past wing failures, seek advice from those that have built and those that know way more than me, where best to inspect with both mirror and boroscope for potential cracking or fail points.
The plane is currently undergoing its annual condition inspection, all of Vans published service bulletins have been complied with and are reviewed prior to each inspection. Any advice regarding enhancing the thoroughness of my inspections would be much appreciated, thanks in advance!

 

[Ironflight]

Since the “B” wing is completely different from the original (and the original that was modified to “A” status…), you dont’ really have to worry about an “A” wing failure occurring in the “B” wing spar. The “B” wing is really a miniature version of wings designed for the -7 and -8.

The thing most folks don’t think about is that inflight breakups (of all aircraft, not just RV’s) usually start when the tail fails or comes off. The loss of the tail leads to an immediate pitch down, causing wings to fail in the negative-G direction (this is the classic “pulled the wings off in a thunderstorm mishap). If you have a “B” wing, I woulnd’t worry about the wing suddenly and unexpectedly failing on you all by itself - I’d look at how well your tail is designed and built - but more importantly, how it is attached. The original RV-4 horizontal stab forward spar looks really wimpy to those of us used to the later designs - even the RV-3 has been upgraded to the newer structure. But the attachment depends on those two forward spar attach bolts being drilled perfectly to the longerons, the rear bolts properly drilled, and the forward spar-to-root ribs being free of cracks (or being re-inforced).

So if I were worried about structural failure, and what you can inspect for, I’d concentrate on the tail…and that is exactly what I do when performing condition inspections on our birds and when I do DAR inspections on others.

 

[rmarshall234]

This^^^

Sadly, the ballsy guys and gals at the Reno Air Races have proven Ironflight’s point. Time and time again.

 

[ronrapp]

The thing most folks don’t think about is that inflight breakups (of all aircraft, not just RV’s) usually start when the tail fails or comes off. The loss of the tail leads to an immediate pitch down, causing wings to fail in the negative-G direction (this is the classic “pulled the wings off in a thunderstorm mishap). If you have a “B” wing, I woulnd’t worry about the wing suddenly and unexpectedly failing on you all by itself - I’d look at how well your tail is designed and built - but more importantly, how it is attached. The original RV-4 horizontal stab forward spar looks really wimpy to those of us used to the later designs - even the RV-3 has been upgraded to the newer structure. But the attachment depends on those two forward spar attach bolts being drilled perfectly to the longerons, the rear bolts properly drilled, and the forward spar-to-root ribs being free of cracks (or being re-inforced).

So if I were worried about structural failure, and what you can inspect for, I’d concentrate on the tail…and that is exactly what I do when performing condition inspections on our birds and when I do DAR inspections on others.

I believe this to be the most useful piece of information I have yet read on this site. Thank you.

--Ron