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Something is bothering me about Rob Logan's hinge wear problem. The
enlarged hole indicates that the bolt has been rotating in the aluminum
hinge bracket. The hinge bracket should not be moving relative to the
bolt.
The stabilizer side of the hinge has a pressed-in bearing that consists
of a sleeve and a barrel-shaped insert (I don't know the proper name for
this). Both of these are hard steel, which is supposed to provide a
durable bearing surface.
When you tighten the nut and bolt, the tabs of the hinge bracket should
flex inward to provide clamping pressure against the ears of the
barrel-shaped insert. When the elevator moves, the hinge, nut, bolt, and
barrel should all rotate together. The only relative motion is between
the barrel and the steel sleeve.
Was the bolt under-torqued?
Are the hinge bracket tabs too stiff to flex inwards?
Hinge wear is a particularly troubling issue, since this type of bearing
is used all over our planes, especially in the control system. Am I
right to worry about this?
Adam Molny
Legacy #151
From: Rob Logan <Rob.Logan@Philips.com>
also note the bolt is harder than then Al "hoop". I noticed
black Al oxide from the outside "hoops" after 30hrs of legacy
flight.. One could wiggle the elevator inside the expanding "hoops".
I made a fatter "hoop" and hard coated it..
http://rob.com/lancair/2003.05/thumb/new.jpg
http://rob.com/lancair/2003.05/thumb/old.jpg
--
Utopian Maturity: Eternity, Liberty, Equality now Fraternity & Altruism.
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