Jim, et al,

The torque values in the link provided looked to be very low for the bolt strength quoted (125 to 145 ksi).  There was no source stated in the table.  After some searching, I found these values to be nearly identical to a table found in AC43.13-1B.  The only rub is that this particular table loaded the bolt to only 40,000 psi for the tension application and only 24,000 psi for the shear applications.  Utilizing full bolt strength requires quite a bit more torque.

For example the required torque for a 3/8" fine thread bolt in tension goes from 160-190 inlbs to 390 inlb to reach 90 ksi.

 

The story does not end there however.  There exist applications that should not be torqued to the rated value of the bolt.  The materials being clamped may not be able to support the full clamping load of the bolt.  For example, the 3/8" Hartzell propeller hub bolts, that also hold the spinner backplate, should not be torqued to 390 inlb.  Hartzell limits the hub bolt torque to 264 inlb.

 

Chris Zavatson

N91CZ

http://www.n91cz.net/ 

From: Jim Nordin <panelmaker@earthlink.net>
To: lml@lancaironline.net
Sent: Wednesday, October 10, 2012 1:04 PM
Subject: [LML] Torque

http://www.hangtowneaa512.org/techdocs/torqueval.pdf

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of peter
Sokolowski
Sent: Wednesday, October 10, 2012 2:46 PM
To: lml@lancaironline.net
Subject: [LML] Torque

Hi,

I am just mounting the wings of my 360 MKII (finally) and want to use the
right torque for the screws. I did not find a number in the manual and could
not locate it in the LML too.

Can someone please help me out ?

Thanks in advance,

Peter
D-EPSO 360 MKII (hope to fly in December / January 2013.....)


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