Mailing List lml@lancaironline.net Message #63150
From: PAUL HERSHORIN <paulhershorin@bellsouth.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Torque
Date: Sun, 14 Oct 2012 17:47:43 -0400
To: <lml@lancaironline.net>
Thanks--I will look into the tork for that bolt, pull the bolts and replace them with new one's.
Paul

--- On Sat, 10/13/12, Dan Schaefer <dfs155@roadrunner.com> wrote:

> From: Dan Schaefer <dfs155@roadrunner.com>
> Subject: [LML] Re: Torque
> To: lml@lancaironline.net
> Date: Saturday, October 13, 2012, 8:32 AM
> 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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