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Richard Swain <rlbks@almatel.net> wrote:

>>>>>
Hello, I'm Richard Swain and am in the process of building
a Lancair IV.  Presently working on the elevators.
It has been suggested to me that instead of riveting the
piano hinge that I may want to bolt it on.
Sounds like a good idea to me,. for future replacemnet if necessary.

Any sugestions as to what size bolts?
<<<<<

If you're really intent on using screws to mount your trim tab hinges you'd
probably do best with MS24693C26 (SS 6-32x3/8, I _think_ 3/8 will do the
job ) and MK1000-06 mini-nutplates.  You should have adequate skin
thickness once you build up the interior to make the hinge knuckles flush
with the outside surface to get decent countersinks, and using SS screws
will keep things looking good after being out in the elements for awhile.

I used the rivet method to install my trim tab hinges and it worked out
just fine.  Considering the relatively small movement of the trim tab I
can't imagine that the hinges will wear out any time soon, so for my way of
thinking worrying about having to replace them doesn't enter into the picture.

The neatest method I've seen (and intend to use on my other trim tabs) for
installing those hinges is to bond them in, a process which I believe is
outlined in some detail in the L-IV Fast Packs.  No fasteners to fiddle
with, and a very clean and solid installation when done properly.
Basically, a series of varied sized holes are drilled along each hinge
blade to allow the potting material to flow through and provide additional
mechanical fastening strength, (Hysol/flox works best) and then the entire
blade is covered with a standard 2-BID layup, overlapping the hinge blades
right up to the knuckles and onto the inner skins by an inch.  If I've left
anything out I'm sure one of our other L-IV builders can fill in the
blanks.  I hope this helps you out.

   <Marv>