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11-03-2016, 11:06 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Tank attachment to the fuse
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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11-03-2016, 11:41 AM
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Join Date: Jun 2005
Posts: 846
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Bolts
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
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11-03-2016, 11:46 AM
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Join Date: Aug 2009
Location: Southern California
Posts: 882
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Quote:
Originally Posted by Bavafa
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
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Did you follow the installation instructions for that fastener? It does not get fully torqued so that the tank brackets can easily separate without rupturing the tank in a wing-shear event such as an off-field landing. A standard lock-nut is not appropriate for this and a drilled-head bolt must be used and safety wired. A nutplate is probably specified because it would be somewhat difficult to install a cotter pint with a castle nut in that location.
Skylor
Last edited by skylor : 11-03-2016 at 11:50 AM.
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11-03-2016, 11:58 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Quote:
Originally Posted by skylor
Did you follow the installation instructions for that fastener? It does not get fully torqued so that the tank brackets can easily separate without rupturing the tank in a wing-shear event such as an off-field landing. A standard lock-nut is not appropriate for this and a drilled-head bolt must be used and safety wired. A nutplate is probably specified because it would be somewhat difficult to install a cotter pint with a castle nut in that location.
Skylor
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I did follow the instructions and mine is not torqued for the very reason that you have mentioned. But still it does not make it any more clear as why a nut plate and not a standard locknut. If there is one bolt/nut that you have full unrestricted access to it, it would be this one 
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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11-03-2016, 11:58 AM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by Bavafa
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
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Not singling you out because this happens all the time, but deviating from what the plans specify and then admitting that you don't have any idea why the plans say what they do is not a good idea.
A nut plate is used for a very specific reason.
In some crash situations the wing may deflected aft which causes the fuel tank to move outboard away from the fuselage.
The design of the joint is to allow the bracket on the tank to pull away from the support bracket on the fuselage instead of the root rib being pulled out of the tank. The nutplate is used to help minimize the likelihood of the of the fastener being able to tilt sideways and jamb up instead of allowing the clevis on the fuel tank to freely slide out. So it is also important to orient the nutplate laterally as shown in the drawings and to tighten the bolt as described in the plans/manual.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Last edited by rvbuilder2002 : 11-03-2016 at 02:18 PM.
Reason: replaced auto deleted / illegal word
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11-03-2016, 12:00 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by 6 Gun
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
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My only comment to this is to refer to my comments in my previous post and then ask "do the plans say only tighten the bolt finger tight"?
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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11-03-2016, 12:02 PM
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Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,189
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Quote:
Originally Posted by Bavafa
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
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If you have a flop tube in the tank (mine is in the left), you will likely find that the threaded end of the bolt interferes with the line installation.
__________________
Ray
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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11-03-2016, 01:08 PM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by 6 Gun
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
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Funny Bob -
I think I have contributed to this,...
The fact that there is such a wide array of what is done here, and there has never been an incident, accident, or whatever that I am aware of may tell us something...
Still, Scott is our best resource and I follow whatever he tells me, even if I don't readily see the light. Scott was a hangar mate years ago for a short time, and in his day job, well... this is what he does for a living, and he has done it for a long time, and done it well.
So, the things I learned;
The rear spar can move, at least when heavily g loaded. The fact that some, like mine, show no evidence of it, doesn't mean anything.
Follow the plans.
Whenever anyone I respect like Vic posts a safety concern, I listen. But... I also want to know exactly why. Sometimes this keeps a thread going. I am not sure that is bad thing if we can keep away from the misinformation that many, including myself, might be guilty of spreading. However, any discussion about safety can't be bad.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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11-03-2016, 02:28 PM
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Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,791
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Quote:
Originally Posted by 6 Gun
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
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make sure the grease does not promote corrosion. I have seen some strange corrosion on steel from special high pressure grease.
__________________
Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all
Simplicity is the art in design.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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11-04-2016, 09:42 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Quote:
Originally Posted by rvbuilder2002
Not singling you out because this happens all the time, but deviating from what the plans specify and then admitting that you don't have any idea why the plans say what they do is not a good idea.
A nut plate is used for a very specific reason.
In some crash situations the wing may deflected aft which causes the fuel tank to move outboard away from the fuselage.
The design of the joint is to allow the bracket on the tank to pull away from the support bracket on the fuselage instead of the root rib being pulled out of the tank. The nutplate is used to help minimize the likelihood of the of the fastener being able to tilt sideways and jamb up instead of allowing the clevis on the fuel tank to freely slide out. So it is also important to orient the nutplate laterally as shown in the drawings and to tighten the bolt as described in the plans/manual.
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I don?t mind to be singled out if it is done with good intention and constructive criticism.
I had talked to VANS just to make sure my deviation is not of a great concern and they confirmed that as long as it is properly safety wired/cotter pinned. FWIW, my thoughts on the use of a nut plate was due to the fact that since this is not a properly torqued bolt, it has a greater chance of coming loose, hence both the bolt and nut needs to be fixed. I think it is also important to note that the safety wire ought not to go to the slotted bracket, just for the reason you have stated.
On other notes, if my memory serves me right, Vans suggested normal torque value for the aft bolt and not finger tight.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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