Hello group,

thanks to all who have responded to my question. As always - fast and
valuable.

Cheers,

Peter

-----Ursprüngliche Nachricht-----
Von: Lancair Mailing List [mailto:lml@lancaironline.net] Im Auftrag von Dan
Schaefer
Gesendet: Samstag, 13. Oktober 2012 14:33
An: lml@lancaironline.net
Betreff: [LML] Re: Torque

Paul, over-torquing even the high quality (125,000 - 160,000 psi) AN bolts
can be as bad as under-torquing. With enough torque, the bolt shank can be
stretched to failure. If you don't know how much force with which your main
spar bolts were installed, you could - repeat "could" - be set up for a real
problem. Over-torquing the spar bolts has an additional problem you probably
haven't considered (aside from a catastrophic failure under load i.e.
failure in flight) - should an outboard bolt fail while it's being
installed, I doubt that getting the broken remainder out of the spar without
cutting into the wing-skin is possible. At least on the LNC2's.

Use the published dry-thread torque values for which these fasteners are
designed. A good (calibrated) torque wrench is a small but invaluable
investment for an airplane builder if you really intend to commit aviation
in it.

Regards,

Dan Schaefer


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