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  #1  
Old 02-12-2014, 03:37 PM
dsm8 dsm8 is offline
 
Join Date: Oct 2006
Location: Madison CT
Posts: 68
Default Torquing Bolts

Good evening:

What do people use for a torque wrench. I am using a 1/4" click type and am deathy afraid of under and over torquing. While using the nuts with the nyon inserts it feels like it needs more torque than is reccommended. I read some where that you need to add the torque requried to turn the bolt or nut to the reccommended torque setting. With a click wrench how do yo figure this out. Any advice would be greatly appreciated.

Thanks

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  #2  
Old 02-12-2014, 05:12 PM
TangoBravo TangoBravo is offline
 
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Location: Greenville, SC
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Default Torque wrenches etc

There is an excellent manual available on the FAA.GOV web site. It is the FAA-8083-30 general maintenance technician handbook. Chapter 9 is about tools and how to use them
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  #3  
Old 02-12-2014, 05:15 PM
TangoBravo TangoBravo is offline
 
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Location: Greenville, SC
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Default further on torque

For self locking nuts using the insert the "running" torque must be determined. that is the torque that is required to move the nut after the threads engage in the insert. The above mentioned handbook covers that as well
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  #4  
Old 02-12-2014, 08:16 PM
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Rick_A Rick_A is offline
 
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Location: Highland Village, TX
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Default Determining Run On Torque

I agree that adding Run On torque to the desired torque is the most accurate way to torque a fastener. However, for AN3 and AN4 fasteners the run on torque is usually very low - so low that most of us don't have a torque wrench that reads low enough to measure it. For example, my 1/4 drive CDI torque wrench starts at 20 in lbs.

There is a CDI electronic (click type) torque wrenches that starts at 2 in lbs but this wrench costs almost $400.

ATS carries a nice 1/4" dial torque wrench with a scale of 0 - 75 in lbs. This is probably the best tool to measure run on torque but at $230 it's not cheap. Maybe I'll buy one some day.

For now, I just torque the self-locking nuts to the high end of the range specified in AC 43.13 (i.e. 25 in lb for AN3)
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  #5  
Old 02-12-2014, 09:23 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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Default

I usually torque to the high end of the range with lock nuts reasoning that the running torque is likely less than the spread between max and min.

If the bolt is in shear it shouldn't be as critical since the forces don't tend to loosen the nut. It's the bolts in tension like landing gear and props I am particularly careful with it.
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  #6  
Old 02-13-2014, 07:35 AM
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bhassel bhassel is offline
 
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Posts: 963
Default

For the smaller torque values, like measuring the resistance once the bolt goes into the threads, I bought a torque wrench from a bicycle store. It was a 'Park Tool' Model TW-1 and ran somewhere around $50.



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  #7  
Old 02-13-2014, 08:03 AM
novipilot novipilot is offline
 
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Location: Novi, MI & Venice, FL
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Just remember that the objective is to put the bolt in tension, and torque on the nut is an indirect method of estimating how much tension is on the bolt. Things like a drop of oil on the threads, or a dinged thread, or even the correct thread length protruding through the hole will alter the relationship between bolt tension and torque. If we could see the data from a strain gaged bolt vs. torque, we'd probably throw our torque wrenches away. But the wrench provides the best measure that we have at an economical price.
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  #8  
Old 02-13-2014, 09:20 AM
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Jesse Jesse is offline
 
Join Date: May 2005
Location: X35 - Ocala, FL
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Quote:
Originally Posted by RFSchaller View Post
If the bolt is in shear it shouldn't be as critical since the forces don't tend to loosen the nut. It's the bolts in tension like landing gear and props I am particularly careful with it.
Which model of RV's have the landing gear bolts working in tension? All of them that I have worked on are working in double shear.
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  #9  
Old 02-13-2014, 09:23 AM
aerhed aerhed is offline
 
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Jesse, the RV8 gear tries to Pty the nuts off.
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  #10  
Old 02-13-2014, 09:26 AM
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Jesse Jesse is offline
 
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Quote:
Originally Posted by aerhed View Post
Jesse, the RV8 gear tries to Pty the nuts off.
Thanks. I assumed it was something like that. The 6, 7, 9 and 10 are all in double shear.
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