Van's Air Force
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New SB issued 6 May 2016 (SB16-03-28)
- Thread starter Bernie RV7
- Start date
Auburntsts
Well Known Member
2015 RV10, 112hrs, no cracks. More importantly I was able to use a borescope to check the section of the aileron bracket that is covered by the gap seal in lieu of removing the ailerons per the SB. The borescope is a huge time saver if you can get your hands on one-- expensive off the shelf or cheap DIY model, doesn't matter.
gerrychuck
Well Known Member
2003 RV6A, 424 hrs.
No cracks, but a LOT of scratches and tool marks (very different than the workmanship seen on most the airframe) that required a fair amount of high resolution study. Definitely no areas of concern around the uppermost and lowermost rivets that Vans identifies as the problem areas. I'm going to watch a couple of those marks carefully, though (I'll inspect again at my annual in August) just to be sure.
No cracks, but a LOT of scratches and tool marks (very different than the workmanship seen on most the airframe) that required a fair amount of high resolution study. Definitely no areas of concern around the uppermost and lowermost rivets that Vans identifies as the problem areas. I'm going to watch a couple of those marks carefully, though (I'll inspect again at my annual in August) just to be sure.
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Seems as though a reason not to do it would be keeping the ability to inspect this area. Installing the doublers will hide both sides of the spar. This seems to be a relatively rare cracking issue without a fully understood (by me, at least) cause. I haven't had time to analyze it, but I'm wondering if a better enhancement for those of us still under construction might be a partial rib that would put the aileron bracket loads into the skin.
Where is the load coming from that causes the cracking? Stick input forces being reacted against the aileron stops, maybe?
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Mattmountain
I'm New Here
RV7a
350hrs, good mix of aero and cross country time. No cracks ! Took a total of 15 min to open, inspect, photo and close back up
350hrs, good mix of aero and cross country time. No cracks ! Took a total of 15 min to open, inspect, photo and close back up
f14av8r
Well Known Member
RV-4 No Cracks
Inspected my 1993 start 2000 completion RV-4 with 1050 airframe hours - NO CRACKS. I've flown a lot of aerobatics during the last 150 hours but I don't think the previous owner flew aerobatics often.
The first photo is a cell phone photo and was adequate to the task but the borescope provided a little closer look.
Cell Photo
Borescope
Inspected my 1993 start 2000 completion RV-4 with 1050 airframe hours - NO CRACKS. I've flown a lot of aerobatics during the last 150 hours but I don't think the previous owner flew aerobatics often.
The first photo is a cell phone photo and was adequate to the task but the borescope provided a little closer look.
Cell Photo
Borescope
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?).
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?).
ArVeeNiner
Well Known Member
210 hours, no cracks. RV9A.
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
rmartingt
Well Known Member
I'm kind of torn on this one. My bottom skins are on, but I haven't riveted the flaps on yet. My wings are in the cradle and easier to work on. I'm wondering if it's worth it to go ahead with the mod while the wings are still somewhat easy to work on. I'm even willing to drill out and re-rivet a rib bay or so (bottom skin) if it'll lessen the chances of boogering up the spar. The hard part would be drilling out the hinge bracket rivets--IIRC I put the manufactured head on the inside.
Then again, it seems the odds of a crack are low, and the airplane could go its whole life without an issue.
Then again, it seems the odds of a crack are low, and the airplane could go its whole life without an issue.
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.
People here are just trying to find a correlation between (ab)using their airplanes in a certain manner and cracks resulting... 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 reality is that there are *lots* of places in an RV that you can't see once it's built. You have a -6, you know this. I just pulled a fuel tank off for the first time to fix a leaking inboard access cover. I've never before looked at the front of my spar from the fuselage to the end of the fuel tank bay. I don't see anything untoward, but I wouldn't expect to either... Just like I wouldn't expect to see cracks forming in the middle of my rear spar, and wouldn't think to go looking for them.
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?
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.
It's not surprising *where* they occur, but that they are occurring at all is possibly indicative of a *design* error, is it not?
Honestly, I don't think so...I think you just have a lot of airplanes out there and some small percentage will have oddball failure modes which can never be traced to a definitive root cause.
But it's worth asking, I think: main wing rear spar, horizontal forward spar, elevator spar...
Rob,
I see these two points to be direct contradictions.
In one you imply that people wouldn't need to inspect something that is clearly inspectable, but in the other you say that if the cracks were there you think they would have seen them.......
Because this location is clearly visible it should be inspected by everyone at each condition inspection even without the issuance of a SB, but you suggest that you don't think the lack of reports previously isn't likely because people weren't looking? But then you suggest that with more information people wouldn't have to bother?
That may be true. Maybe the cracks are only now becoming large enough to be visible, but your implication that people might not have to inspect if we knew the root cause is exactly why I have said that the information is of no value.
There are no absolutes.
Even with a detailed poll of customers of all of the factors you and others have mentioned (big engine, aerobatics, rough handling, poor workmanship.... how do you really quantify what many of these really mean?), and as many other possible factors that we could think of, it would be impossible to say one way or the other for certain if a specific airplane might have a high probability for cracks.
You have just proven what I have said from the beginning.... that the information you seek would likely just make people apathetic about doing the inspection. 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.
I am not meaning to be critical... it is not necessarily their fault.
The fact is that the skills developed while building an airplane do not develop all the knowledge and skills you need to do a detailed inspection on one. Especially the skills need to look for some of the problems that begin to show up as an aircraft ages.
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.....
PerfTech
Well Known Member
....By nature and design, airplanes need to be as light as possible if one is expecting optimal performance. This is why Caterpillar doesn't build aircraft, and if they did, you wouldn't want one. I seriously doubt there were any workmanship issues with Vans demonstrator that contributed to the cracking. More likely just one of those thing that comes with age. As stated before, these types of issues do crop up with age, and are to be expected. We are all very lucky that we have a conscientious company like Vans, and a vary vast network for support to show us and help us when these thing show up. I have a friend who purchased a very well built, experimental small plane, designed by a very well established company. This particular model of plane didn't sell, as it was just far too expensive for the existing market. It is a beautiful, well built, nicely designed, extremely fast and efficient airplane. But, due to the fact that only a very few exist (perhapps six or seven), I am scared and concerned for him and what may occur with no support or warning of issues. He is out there virtually all alone, with very limited mechanical knowledge or experience. He and his aircraft are truly an experiment! Comparatively speaking, our Vans aircraft border on being certified, without all the nightmare and hassle that accompanies owning one. We as a group are truly blessed. Thanks, Allan..
Suggestion if I may ...
Add a section to your manuals for ongoing inspection and maintenance? Yes all the aircraft vary, but for a given kit you sell, that maintenance should be well defined. So for the airframe, here's what you should do. You bought our FFW kit? There's a maintenance section in there too ... filters, adjustments, inspections, etc. and so on. Sometimes maybe you just refer to the manual for given piece of kit of course, but still, there's a central place.
If I build everything 100% per Van's using all your kits, I end up with a good complication of maintenance instructions. Provides added value too ... if I do much more custom work, determining the proper maintenance activities can be a lot more work ... and expensive (when you learn things the hard way).
Plummit
Well Known Member
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
Q: if this is caused by air loads (the cracks on the rear main wing spar), what about the *outboard* brackets? I don't normally remove the wingtips during an inspection, because there's really nothing to inspect there, but now...?
All my comments in this thread are generalized.
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. Hense the inspection recommendation. You can argue what ever you want ( it kind of sounds like you want to), but all I said was that people should be inspecting places that are visible.
As for vans providing guidance on inspecting? I am not sure what you are looking for. Vans doesn't teach how to build the airplanes via a text manual so not sure how to step into teaching how to inspect them via a text manual.
As of today it looks like we firmed up a plan for an OSH forum on the subject so stay tuned for more info.
Until then, here is some food for thought.......
One of the biggest differences between a builder and an A&P doing a condition inspection is that the mental tendency of a builder is that they don't expect to find anything wrong (we believe we did everything perfectly), where as the A&P does expect to find something wrong.
Point is, doing a good job on an inspection is as much attitude and frame of mind as it is anything.
More later.....
david.perl
Well Known Member
33 hours, no cracks, phew
The RV-10 (potential) cracking I was talking about was talking about in my post was on the bracket flange bends. Not the rivet holes in the spar web (though I am pretty confident the post that you linked to is not a crack.... I posted that in that thread).
MrMoisture
Active Member
A friend & I performed the SB inspection on both my -8A & -10. I purchased this $23.00 USB Borescope from Amazon and was able to reach all forward spar areas by just removing the inspection covers. We did tape the camera to a telescoping magnetic extension wand to stiffen the scope which allowed much greater control & rotation. We inspected the aft areas by sliding the scope into review position for both aircraft.
Not sure why Vans wouldn't suggest this as a possible inspection solution as it avoids removing & reinstalling control surfaces when it's not needed.
Good luck all!
Not sure why Vans wouldn't suggest this as a possible inspection solution as it avoids removing & reinstalling control surfaces when it's not needed.
Good luck all!
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
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https://drive.google.com/open?id=0B5khQo5AKuPZWmw2SlNfbVlVOFk
AMOC for RV-10 Aileron Bracket inspection
Attached is a photo of my RV-10's right aileron bracket (top side, the portion behind the gap seal) taken with a borescope (ViVida AbleScope VA-400, $150 from Amazon). I've not trimmed the gap fairing yet, because the borescope approach seems to provide adequate inspection of the bracket, and takes only a few minutes.
I sent message to Van's: "Based on my photo, does the borescope approach seem adequate to you?"
Reply from Gus was "The photo is clear enough to see there’s no cracks. The only reason for the trimming is because we assume most builders will not have a borescope. Also, if you do have cracks, it will need to be trimmed for access to the rivets."
Attached is a photo of my RV-10's right aileron bracket (top side, the portion behind the gap seal) taken with a borescope (ViVida AbleScope VA-400, $150 from Amazon). I've not trimmed the gap fairing yet, because the borescope approach seems to provide adequate inspection of the bracket, and takes only a few minutes.
I sent message to Van's: "Based on my photo, does the borescope approach seem adequate to you?"
Reply from Gus was "The photo is clear enough to see there’s no cracks. The only reason for the trimming is because we assume most builders will not have a borescope. Also, if you do have cracks, it will need to be trimmed for access to the rivets."
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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
Looks good, but it does look like the push/pull tube in each wing is rubbing on the spar opening though (and recover the loose washer).
Thanks Scott. I took out the washer when I took the picture. I also noticed a plastic tube in the left wing; I'll take it out also. 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.
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.
If it were continuing to rub on an ongoing basis i'd expect to see more residue in the bottom of the wing cavity, and/or some witness marks around the opening showing where it's hitting. Maybe a photo from a slightly different angle can capture that.
The easiest cure depends on how much clearance there is at the extremes of control travel.
This type of rub typically happens only at the very extreme of control travel. Since we rarely (if at all) use the extremes, the rubbing may not be very evident in day to day operations.
The push/pull rod changes position within the opening when the aileron moves through its travel range, but if there is good clearance for the push/pull rod with the aileron at the opposite extreme of travel, then using different hardware positioning to adjust the mounting position of the rod end would be a good way to resolve it.
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.
If making an adjustment with one or both of these wont resolve any rubbing, then enlarging the opening slightly is the only remaining option.
Mountain Time
Active Member
SB 16-03-28
RV-6, 478 hr, no cracks.
I need to fly more
RV-6, 478 hr, no cracks.
I need to fly more
What makes you believe that is not a crack? I know it is unlikely to crack at the second rivet from the top but the "mark" goes through the rivet.
rightrudder
Well Known Member
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.
Why not just open the hole up a bit more in all these cases? Seems like that's the easiest solution...and it's not the only place you're likely to have to open a hole some (elevator pushrod through the rear spar, stick-to-aileron pushrods through the fuselage and wing lightening holes, etc.
