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04-11-2010, 09:52 PM
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Join Date: Jan 2005
Location: SoCal
Posts: 2,061
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To clarify just how low this torque is, I did mine with a torque screwdriver. It's a pretty good twist with only one hand, but nowhere near enough to snap a bolt. I suspect you've mistakenly used a foot pound wrench, thus cranking on 12 times the proper torque. If that is the case, you'll need to replace the other bolts since they are now stretched.
__________________
Steve Zicree
Fullerton, Ca. w/beautiful 2.5 year old son 
RV-4 99% built  and sold 
Rag and tube project well under way
paid =VAF= dues through June 2013
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04-12-2010, 05:34 AM
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Join Date: Jun 2005
Location: Locust, NC
Posts: 440
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less than expected
The first time I used my new inch-pound torque wrench, it lightly clicked as soon as I moved it on the nut. I kept turning and realized something was wrong. I set up a fixture and tested my wrench and found it to be extremely accurate full scale. Problem was my being used to foot-pounds. With the AN3 bolts, if you only snug them down a little before reaching for the torque wrench they are probably too tight.
Alex brought up a good point concerning locknuts. If they take 10 inch-pounds to turn by themselves and you want 25 inch-pounds, set your wrench to 35 inch-pounds.
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Dave
M20C
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04-12-2010, 09:41 AM
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Join Date: Jan 2006
Location: Vonore, TN
Posts: 369
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Broke Mine Also - Lesson Learned
I snapped off a couple of AN3 bolts on the same fixture until I realized that my Craftsman "click-type" torque wrench really doesn't click at low torque, the head just kind of leans over and touches the barrel. At 20-25 inch pounds I can deflect the head of the wrench with my thumb pressed against the side of the ratchet mechanism.
__________________
John Tierney
Vonore, TN
RV-7A - N777JT Flying
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04-12-2010, 02:37 PM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by John Tierney
I snapped off a couple of AN3 bolts on the same fixture until I realized that my Craftsman "click-type" torque wrench really doesn't click at low torque, the head just kind of leans over and touches the barrel. At 20-25 inch pounds I can deflect the head of the wrench with my thumb pressed against the side of the ratchet mechanism.
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I have several sizes of Craftsman click wrenches. The smaller unit clicks with "certainty". 25 inch pounds would be about 1/3rd of it's range.
L.Adamson
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04-12-2010, 03:43 PM
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Join Date: Feb 2010
Location: GTA, Ontario
Posts: 826
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Thanks for all of the responses, much appreciated. There are several things I will be looking at:
Removing the other 3 bolts and having the torque wrench checked for proper calibration. The torque wrench is brand new, of good quality, and was recently calibrated. I?d be surprise if it was that, but hoping it is that.
The bolts will be replaced. The settings were at exactly 23 in/lbs. Plans call for 20-25 in/lbs.
The one bolt may very well of had a fault in it. Not a whole lot of force was even applied to it. I?m going to send Van?s a picture of it as it was a clean snap.
Of interest, I had a direct reply by way of email from a forum member, which wasn?t posted here. I don't know if it was to offer some insight or other. I'm not quite convinced that purchasing a torque wrench to correctly set torque settings as recommended by the manufacturer is a "waste of money", even for an AN3 bolt...going by "feel" doesn't do it for me, especially when aircraft have lost tail sections in flight. Plus there are other bolts that require proper torque settings later in the build, which for me justifies the expense.
As far as the bolt being counterfeit, I don?t believe that Van?s would send such items in their kits?My father is a NDT technician and from time to time, the most well built parts at times do contain flaws, cracks, hairline fractures, etc, and until some stress or force is applied, it looks good. I hope I just had a defective one. In any event, Van?s will be made aware of it and I will post back on the conclusion from the torque wrench.
Much thanks folks!
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04-13-2010, 07:20 AM
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Join Date: Sep 2006
Location: Roma, Italy
Posts: 510
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I had problems in the very few stages of my RV building experience.
When I received my QB wings, I had to unscrew and retorque 4 bolts on the aileron bracket. Those bolts which go on hidden platenuts riveted on the blind side of the longeron.
I noticed that bolts were factory-torqed at approx. 75 inch./lbs.
So, I had the terrible idea to retorque them at that level and one of them got stripped. I had to disassemble all the 100 or so screws and bolts on the fuel tank to get to that platenuts, remove them and the stripped bolt, reinstall new ones.
What I would like to underline is that it took 75/80 inch./lbs. to strip that bolt.
At 23 inch./lbs. I guess it is not possible that the bolt was faulty. At 23 inch./lbs. one can tighten the nut almost with fingers. I guess your torque wrench had something wrong.
__________________
RV4 IO-320, Catto 3-blade, Christen, I-BILT
Flight time: 1 hour
Status: test flights
www.rv4.it
ROME, Italy
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RV9A O-320 D1A, Hartzell C/S prop, slider, I-PRCA
Flight time: 350 hours
Status: SOLD
http://nuke.rv9.it
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04-13-2010, 09:24 AM
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Join Date: Jan 2005
Location: Near Scipio, in Southern Indiana
Posts: 1,779
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In thirty plus years of building/wrench turning, I have seen a total of one AN bolt snap with less than recommended torque. It was a tensioning bolt on a throttle control and had very minimal torque. The head had a crack that was obviously there when it was installed. The aircraft owner looked the situation over and spilled his groceries. He spent days going over the whole ship, as well he should. Was it counterfeit? No idea, but it was 20 years ago. It can happen...
Bob Kelly
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Bob Kelly, Scipio, Indiana
Tech Counselor
Founder, Eagle's Nest Projects
President, AviationNation, Inc
RV-9A N908BL, Flying
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04-13-2010, 10:03 AM
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Join Date: Jan 2005
Location: The Beautiful NJ Shore
Posts: 409
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You Need This
You need to go to a bicycle shop or online to get one of these:
http://www.parktool.com/products/det...t=13&item=TW-1
This will do all your AN3's and most AN4's.
__________________
Greg Piney
RV-8 2547
Empennage Done!
Beginning Fuselage Final Assembly!
(Tub finished, on to Landing Gear).
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04-13-2010, 12:58 PM
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Chief Obfuscation Officer
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Join Date: May 2005
Location: Livermore, CA
Posts: 1,110
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Quote:
Originally Posted by John Tierney
I snapped off a couple of AN3 bolts on the same fixture until I realized that my Craftsman "click-type" torque wrench really doesn't click at low torque, the head just kind of leans over and touches the barrel. At 20-25 inch pounds I can deflect the head of the wrench with my thumb pressed against the side of the ratchet mechanism.
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Funny that you mention this... I had a friend return 2 Craftsman wrenches because he kept breaking AN3 bolts. He brought the third wrench over to my house and when I showed him the how the wrench lightly clicks and "leans" when the torque setting is acheived all he said was, "Ooooohhhhhhhh, I was waiting for the wrench to go click-click-click, so I kept tightening."
Yes, I applied the requisite Dope Slap to the back of his head. 
Last edited by RV7Factory : 04-14-2010 at 04:37 PM.
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