lorne green
Well Known Member
Vans latest SB for 7/8/9's wing attach bolts
SB date 12/08/14
http://www.vansaircraft.com/pdf/sb12-08-14.pdf
SB date 12/08/14
http://www.vansaircraft.com/pdf/sb12-08-14.pdf
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It's quite hard to blame the builders for not putting in bolts that Van's forgot to include in the plans NB the Revision issue of the RV-8 drawing, guess what changed in Revn 1 , and no alert put out to those who were building to Issue 0.I guess some folks were so focused on dealing with the close-tolerance bolts that they forgot the others?
thanks Lorne;
I know its difficult, but for us non-builders, sure would be nice to know what we are looking for;
any chance someone ( or Van's) has a photo, ideally with and without the bolt visible?
..and what exactly does it DO?...if aircraft are flying around without it?
thanks
I looked through my construction photos and had several showing them installed... although I was sure that they were, it was nice to see the shots and it is fun to visit memory lane of the build.
Um, that might be me.I know somebody who had them missing I believe until the first Annual. I counted my 10 bolts in each wing many times before I moved on. Yikes!
Did our 7A inspection. Remove top portion of wing root fairing and find the two nut plates by standing in front of the wing. If you see threads sticking though the nut plate ou are good to go.
Phelps
All four AN4-13 bolts were not installed in my RV9A. I could not align the bolts to the nut plates in the wing spars. I am not the builder and in the previous two condition inspections was unaware of this problem until this service bulletin.
I need some advice here. Any suggestions anyone?
All four AN4-13 bolts were not installed in my RV9A. I could not align the bolts to the nut plates in the wing spars. I am not the builder and in the previous two condition inspections was unaware of this problem until this service bulletin.
I need some advice here. Any suggestions anyone?
Could someone explain the functional purpose for these bolts? I pulled the seat pans out to find my spars did not have the bolts installed. And I was the installer. It is disheartening to think I missed something that was critical. However, I have been flying for 2 years and 190 hours without them. So, what exactly are these bolts doing that I could fly for so long without consequences? As far as I can observe there have been no adverse effects of flying without them in my case. Any comments about their functionality is appreciated.Um, that might be me.
Back in 2007 I posted this thread on the subject.
I'm a bit surprised it took Van's this long to come out with a Service Bulletin.
The good news is, the plane will fly without those bolts. The real question is, how many G?s can you pull before the spar buckles.
Could someone explain the functional purpose for these bolts?
This makes a lot of sense. It also may explain why my non-aerobatic 9 may not have had any issues with not having the bolts in place. I have not put much G loading on the structure in the 190 hours of flight. The closest may have been some flights in turbulence or perhaps a 1.5 pull up or something. I have definitely not put the structure in much of a high stress environment to date.**** Grain O' Salt Advisory: I am not an engineer, though I do a fair handful of mechanical design and even some engineering under supervision. ****
As I understand the structure, those bolts transfer shear out of the wing spar shear webs and into the fuselage bulkhead.
Obviously, the structure seems to work adequately without them in the short term, when operated moderately. The bolts that secure the wing spar stubs to the big aluminum bars that span the cockpit, and also to the bulkheads, seem to transfer enough shear to pretty much do the job.
My guess is that engineering analysis of the structure shows that at high load factors (Gs), and after much cyclical loading, the structure might tend to fatigue and crack at the rivets and bolts that attach the spar stubs and transverse bars near the side of body. The extra bolts help distribute the shear loads more evenly into the fuselage, resulting in a structure with a greater load capacity and longer fatigue life.
Thanks, Bob K.
This makes a lot of sense. It also may explain why my non-aerobatic 9 may not have had any issues with not having the bolts in place. I have not put much G loading on the structure in the 190 hours of flight. The closest may have been some flights in turbulence or perhaps a 1.5 pull up or something. I have definitely not put the structure in much of a high stress environment to date.
Well, not sure why you ask but to answer your question, NO I did not push the positive G envelope. I did push to 2.0 g's during Phase 1. However, since I have no aerobatic training and I am not a certified test pilot I was not going to push the airframe to the documented limits of the airframe. Reason being that this is a non-aerobatic airplane, I am a non-aerobatic pilot. The CG, W&B and all other aspects associated with the airframe construction were built to the kit manufacturer's standard. I have built the plane for travel purposes not for high G maneuvers. And yes, I am falling back on the engineer's documented limits of the airframe without actual testing. I am comfortable with relying on that engineering evaluation. Which, by the way, is why I was asking for the reason the engineers included these bolts in the first place when the airplane functioned without them. As I have heard many times in the past: "Margins belong to the engineer". I believe in that and will trust the engineer's margins. That goes for their margins for G loading of the airframe also. I am not going to go there just to satisfy some particular ideal of testing of a specific individual model of the general engineer's design.If you were the installer, and you've still got the plane, presumably you flew it through Phase I. Did you not explore positive G flying traits of the airplane greater than 1.5G during Phase I?
Could someone explain the functional purpose for these bolts? I pulled the seat pans out to find my spars did not have the bolts installed. And I was the installer. It is disheartening to think I missed something that was critical. However, I have been flying for 2 years and 190 hours without them. So, what exactly are these bolts doing that I could fly for so long without consequences? As far as I can observe there have been no adverse effects of flying without them in my case. Any comments about their functionality is appreciated.