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Seeking advice RV3 annual condition inspection

Richard RG

Richard RG

Active Member
Patron
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!
 
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.
 
Ironflight said:
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.
Click to expand...

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

--Ron
 
If we're going to use this thread to cover RV-3 wing (spar) modifications could we have the OP change the thread title to something like "Pre-RV-3B condition inspection advice"?

Again there is no "B" modification.
As mentioned earlier, an RV-3B has completely different wing spars compared to the original RV-3 and compared to any modifications ("A") made to the original spars and wings.

I looked at Van's website and there is no mention of the Change Notices (CN-1 and CN-2) that were issued back in the late 90ies. If there is interest I can scan my paper copies of the change notices and post here so that pre-RV-3B owners can inspect their RV-3s to see if/how they were done. (CN-301 TYPE I, CN2-I SPAR CHANGE).

EDIT: There are a lot of printed pages, so I'll only do it if someone wants the whole RV-3 wing (spar) history and the instructions with pictures for performing the CN2-I ("A") modifications.

Finn
 
FinnFlyer said:
If we're going to use this thread to cover RV-3 wing (spar) modifications could we have the OP change the thread title to something like "Pre-RV-3B condition inspection advice"?

Again there is no "B" modification.
As mentioned earlier, an RV-3B has completely different wing spars compared to the original RV-3 and compared to any modifications ("A") made to the original spars and wings.

I looked at Van's website and there is no mention of the Change Notices (CN-1 and CN-2) that were issued back in the late 90ies. If there is interest I can scan my paper copies of the change notices and post here so that pre-RV-3B owners can inspect their RV-3s to see if/how they were done. (CN-301 TYPE I, CN2-I SPAR CHANGE).

EDIT: There are a lot of printed pages, so I'll only do it if someone wants the whole RV-3 wing (spar) history and the instructions with pictures for performing the CN2-I ("A") modifications.

Finn
Click to expand...
This would be appreciated. Out of prudence I belive this is the responsible way forward. I would like to inspect my -3A before next flight.
 
WillG said:
In addition to what Paul has mentioned about tail attach points.
Confirm that the rear spar bolt hole does not have less than the min. edge margin distance.
Click to expand...
Regarding the tail attach points, can you show the build diagram or reference the page number? This would be for the 3B, the latest plans.
 
- Poindexter - said:
Regarding the tail attach points, can you show the build diagram or reference the page number? This would be for the 3B, the latest plans.
Click to expand...

The RV-3B primarily had a redesigned wing, the rest, fuselage, tail etc. was mostly not changed it seems from the mid 1980 up.
Try page 26. assembly tail drawing
this will show attachment fasteners, location Al. angle and doubler plate callout.
Also check Van's SB for the RV-3, tail group.

mg
 
MoonDog1 said:
I would appreciate this tremendously!
Click to expand...
Looks like David Paule beat me to it:

CN-1 and CN-2, Documents for the RV-3A

These were from Van's website some time ago. Since I'm building an RV-3B, to which these don't apply, I was interested in them and downloaded them. Don't ask me questions about these - I'm not familiar with them at this time. I just scrounged anything I could about RV-3s. Since there seems to...
vansairforce.net
 
Ironflight said:
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.
Click to expand...
Man I really appreciate your input and knowledge of these matters. Thanks and I wonder if there is any kind of list of shops that really know there stuff about these aircraft. Somewhere you could call and schedule a real detail inspection of your airplane that you purchased.

Thanks again!
 
J29racer said:
Any chance of posting pictures of where to look and more detail on “edge margin distance” what ever that means!
Click to expand...
Isn't that covered in Section 5 of the builder manual?

For any hole, but especially for the bolt attaching the wing rear spar to the fuselage, you need at least 2 times the bolt diameter to the nearest material edge.
For a 5/16" bolt that's 5/8" from center of bolt hole to the nearest material edge. In attempts to make wing leading edges square and aligned, a builder may have been tempted to move wings out more than allowed before drilling that critical hole. Or in attempts to set wing incidence, move rear spar up or down more than allowed for the edge distance, before drilling that hole. Or simply drilled the hole closer to material edges than 2 x bolt diameter.

Of course where plenty of material were available we would choose hole center location that were furthest from edges of both materials to be bolted together, thus increasing the margin.
 
Ironflight said:
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.
Click to expand...
I am going through my first conditional inspection on my -4. Thanks for posting. I have printed this and will keep in my conditional inspection checklist.
 
Ironflight said:
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).
Click to expand...

Hello Paul.
Please clarify the ‘original RV-4’. Based on year of kit, specific spar or parts or something else ?

Thanks !
 
Thank you all for the feedback regarding my request for annual condition inspection advice for the RV3b. I've edited my thread title to a more generic request for advice pertaining to inspection of RV3's in general.
Thank you Paul, for highlighting the importance of a detailed inspection of the tail assembly and during my inspection will note edge distance margins of spar bolts.
Hopefully others can add to this thread with specific inspection advice for the pre RV3b wing.
 
jull_under said:
Hello Paul.
Please clarify the ‘original RV-4’. Based on year of kit, specific spar or parts or something else ?

Thanks !
Click to expand...
I have never had or built a -4, but have looked at them now and again. The original Harmon Rocket II used the -4 tail, and I have seen them there as well. If you have a -4 (or any RV), you should have the drawings - if you don;t you can register on Van’s web store and then you’ll have direct access to all teh drawings for your model. I never look at the paper plans for my RV’s anymore - I just grab what I need on the web.

I can’t tell you when (in years) changes have come along, but the original design basically had the forward spar webs continuing inboard of the root ribs to the centrlien of the aircraft. Then there is a splice plate that joins the two of them and the front sppar of the vertical stab. All these parts were sheet metal. In later RV’s, aluminum angles (two of them, one tp, one bottom) were added, with “fingers” that extend outboard of the root rib to actually transfer loads from the stabilizer surfaces into the center section and then to the fuselage longerons. the original design just has one angle riveted to the bottom of the center section (no extension outboard of the root ribs) and bolted to the longerons. One look at a modern RV will tell you instantly how much beefier it is.

Get the drawings for your ship if you don’t have them! For those over you interesetd in the edge distance/longeron drilling, the drawings show that detail as well. If you’re not familiar with it (because you bought the plane), you should definitely study up on how the tail is attached if you’re going to be inspecting it (with your LSRM or A&P license).

Paul
 
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