Hi Rowland,
Having just done the same task a few weeks ago, I'll attempt an explanation.
Forgive
me if some of my explanation is something you already know and understand.
The rudder pedals are secured to a little plywood floor bonded into each
foot-well.
Underneath this floor is a "blind" void which has a flat vertical wall as
part of each foot-well on the inboard side. It is these walls to which my
captive
nuts are attached and consequently it's impossible to secure captive nuts
in the normal way, unless the captive nuts were to be installed before the floor
got bonded in.
Therefore once it has been decided where to position each captive nut, they
should
only be secured as described in the XS engine installation manual. Hopefully
the walls of the duct will fit snugly in contact with the nuts, but mine didn't.
There was a small gap of 3 or so millimetres on each side. Because I didn't
want my duct walls to be tensioned outwards with the AN3-5A bolts and therefore
constantly straining to pull out the captive nuts which are only held by
their little rivets into the foot-well vertical sides, I riveted a penny washer
to each side of the duct to act as spacers.
The captive nuts should be installed as described in the manual for another
reason,
which is to cope better with shear loads at least until the bolts fastening
the duct to its brackets can take the strain off the captive nuts. If you found
that there was enough of a gap on each side of the duct to allow orienting
the captive nuts so that they weren't embedded in the foot-well sides, then
they would probably cope poorly with shear loads and would quite easily tear out
their rivets.
Or so it seems to me.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=466601#466601
|