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Date: Sat, 05 Nov 2005 00:08:18 -0500
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From: "Robert R Pastusek" <rpastusek@htii.com>
Subject: RE: [LML] Re: LNC2 Hydraulic lines/fittings
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Angier Ames wrote:

In the real world, when you can't get a torque wrench into a tight
space to deal with hydraulic lines, what is an acceptable
alternative? Install the nut hand tight and then tighten using a
wrench one or two flats more? How about when installing steel hose
fittings onto aluminum bulkhead fittings?

---
I must admit that this is a trick I used under a large shade tree in Texas,
and is definitely not approved in any aviation repair manual, but it works
for me: Put the assembly you need to tighten in a vice, or if that's not
possible, make up a similar assembly and use that as a demo/test rig.
Tighten it with a torque wrench to the proper value, then use whatever tool
you intend to use in the "real installation" to tighten it just a bit more.
This will give you a feel for how much force is needed. If the wrench is
short, and particularly if your're pulling at an angle less than 90 degrees
to the plane of rotation, you may be surprised at how much force it
takes--but while it's fresh in your memory, do the real job. I tested this
process years ago to see how accurate it was, and was able to consistently
reproduce the correct torque within about 5%. (As an aside, the accuracy
decreased rapidly with time if I didn't apply the lesson right away. On
large parts, my tendancy was to under-tighten; on small parts--particularly
the common 3/16' bolts used in our aircraft, the tendancy was to
overtighten-significantly after a day or two had elapsed from the practice.

Hope this helps,

Bob Pastusek