A quick note for those with wings under construction:
I emailed Van's, told them I was just starting on the rear spar, and asked for advice. They answered "new kits will have the fix included. You can do it, too."
So I ordered the SB kit for a whopping $10. For those of us under construction, it's just a matter of putting two doublers on the forward side of the rear spar, opposite the aileron bracket. No reason not to do it.
I think what's more important than the "what" here is the "why".
Is there an explanation as to what is causing the (few, apparently) cracks in these locations? For the wings, for example, could it be unsecured ailerons being smacked around by high winds and torqueing the brackets? Ham-handed pilots during aerobatics slamming the controls to the side? Or, worse, "normal" forces which are being transferred to the location and then fractures arising at improperly deburred holes, e.g.?
Random responses from a small sample of RVs about presence or absence of cracks doesn't tell us much (and as pointed out, what would you do, NOT inspect them anyway at each annual?).
Sorry, that was poorly worded. What I was getting at is that we've got a long thread here with people commenting "no cracks" or "found a crack, drat!" but there's no context for the results. Aerobatics? No aerobatics? Big engine with lots of vibration? We wont' know. But if anyone calls Van's and reports a crack, I suspect the factory will ask for all these details. In that respect, you'll end up with better data than the survey here, but that data won't be shared.I don't know why you think Van's would do this. What would be the point?
These two previous posts are a generalization of what is going on. I say that because there are many different variables that can come in to play.
http://www.vansairforce.com/community/showpost.php?p=1077420&postcount=56
http://www.vansairforce.com/community/showpost.php?p=1078491&postcount=7
but...is it merely coincidence that these SBs are all coming out regarding spars?
If you consider the fact that by nature a "Spar" is a device for transferring and distributing major loads through portions of an airframe, and that because of that, it has localized point loads..... points where things such as ailerons attach (especially if that thing that attaches is a device where the load is constantly cycling as in when an aileron moves up and down), it is no surprise at all.
If we can figure out what activity causes it, and if we're not doing that, then we don't need to do this SB every year.
The fact that owners haven't seen these cracks before isn't a suggestion that we're doing poor annual inspections, it's an acknowledgement that we can't look at everything and we can't know what the weak points are that we should be highlighting.
Those are interesting, but don't really tell us much...it would be interesting to see the FEA, for example, but I'm sure Van's would never release that sort of data.
I'm wondering if some of these overall structures might not be just a bit too optimized in terms of weight/strength. I'm NOT a structures or mechanical guy (I'm in Systems Engineering), but we now have SBs on cracks: on the forward spar of the elevator; on the forward spar of the horizontal stabilizer; on the rear spar of the main wing. All of those have fixes that involve doublers or additional material in some fashion. Might it be that the material in the original parts is undersized?
I doubt very much this is the case, given the very large number of aircraft and the very few (apparently) instances of cracks (many of which can probably be attributed to poor workmanship and/or hard use/abuse of the airframe), but...is it merely coincidence that these SBs are all coming out regarding spars?
Don't get me wrong. I hold in high value the right of builders to be able to do their own condition inspections, I just think we need to do more to educate them on how they should be accomplishing that.
I recently did a safety seminar on this subject and am looking at other ways to expand the distribution of the info.... possibly magazine article series, etc.....
Rob,
That, on top of the fact that this location should be inspected at each condition inspection, regardless of whether a SB was issued or not.
On the other subject of inspections and whether people do a good job......?
I think many do, but I also think many don't.
Gosh, the SB has us RV-10 owners/builders trimming the aileron gap fairing in order to inspect the hinge bracket sides. It could be argued that prior to this SB, no one did a good inspection if they didn't trim the fairing....
Don't get me wrong, I think that Vans does a fantastic job, but I also feel that more guidance on performing inspections is a good thing!
As a non-builder, I sure want to be able to inspect my aircraft for airworthiness, even if I can't sign it off.
regards
-Marc
The RV-10 is a special case with the bracket inspection. None have ever been found cracked but in the process of doing the FEA it was found to be possible.
The RV-10 is a special case with the bracket inspection. None have ever been found cracked but in the process of doing the FEA it was found to be possible.
There appears to be at least one RV-10
think I'm good to go, right wing no marks, left wing mark likely not a crack; RV-9A, 229 hours
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https://drive.google.com/open?id=0B5khQo5AKuPZWmw2SlNfbVlVOFk
You could first have someone move the aileron back and forth to its limits while you watch inside, and see if it's *still* rubbing. It's possible it rubbed once or twice during or after first assembly (or maybe maintenance), removing the paint, and after that the hole was enlarged to just clear it. The builder may not have bothered to re-paint the control linkage.I noticed the rubbing too. Should I get in there some how to enlarge the opening? I guess I'd remove the control rod at the aileron and file it down some? Or maybe I can use some washers to align it away from the current opening? I haven't done this before and I'm not the builder.
Should I get in there some how to enlarge the opening? I guess I'd remove the control rod at the aileron and file it down some? Or maybe I can use some washers to align it away from the current opening? I haven't done this before and I'm not the builder.
think I'm good to go, right wing no marks, left wing mark likely not a crack;
https://drive.google.com/open?id=0B5khQo5AKuPZWmw2SlNfbVlVOFk
I had a slight rub on final assembly, but all it took to eliminate contact was installing a thin washer at each hinge point for a tiny bit more lateral offset of the aileron. Just make sure that your aileron-to-wingtip and aileron-to-flap gaps are still within spec.It is also possible that during aileron removal at some point (airplane getting painted, etc) that the ailerons got installed in a slightly different lateral position. This could also have an influence on push/pull rod clearance.