[R-390] R390/URR and R390A/URR clamp screw torque

[jkharvie]

 thanks Jim,Very informative
John


    On Friday, July 24, 2026 at 05:04:06 PM EDT, Jim Whartenby via R-390 <r-390 at mailman.qth.net> wrote:   

 NASA torque spec covering different thread materials from aluminum to stainless steel.  Several hundred pages which should hopefully satisfy everyone!

https://ntrs.nasa.gov/api/citations/20170003491/downloads/20170003491.pdf

Jim


Logic is a systematic method of coming to the wrong conclusion with confidence.  Murphy 

    On Friday, July 24, 2026 at 02:58:04 PM CDT, Perry Sandeen via R-390 <r-390 at mailman.qth.net> wrote:  

 List,
I was trained on the R390A in USAF tech school in 1963. There was no training or information given about clamp torque.
However list member Glen Scott who has done total remand (including complete panel restoration) of the R390A for years as a living, posted on this list his experience.  It involved using a torque screwdriver and the value he found optimum for no slippage or clamp  breakage.
I don't remember when it was posted so if someone would re-posit it, it should provide the necessary information needed.
73,
Perry KM6FQV


______________________________________________________________
R-390 mailing list
Home: http://mailman.qth.net/mailman/listinfo/r-390
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:R-390 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html  
______________________________________________________________
R-390 mailing list
Home: http://mailman.qth.net/mailman/listinfo/r-390
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:R-390 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html