Hello group,



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

valuable.



Cheers,



Peter



-----Ursprüngliche Nachricht-----

Von: Lancair Mailing List [lml [at] lancaironline.net (mailto:)

] Im Auftrag von Dan

Schaefer

Gesendet: Samstag, 13. Oktober 2012 14:33

An: lml [at] 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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