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The recent
discussion of elevator hinge play reminded me of a related issue on the MKII
elevator. The root cause of the wear issues in hinges for this particular
location are the loads induced by the torsional input from the
engine. The spherical bearings in the MKII tail are not immune from this
abuse. The original bearings are of the low end COM series. After
some 7 years I noticed that slight vertical movement outboard on the
elevator was now possible. The clunk-clunk sound of metal on
metal was quite distinct. I ended up replacing these bearing
with Aurora Precision Series bearings (LHA 4). The static load rating
is more than double the COM series. Not that we ever expect to
be pulling on the bearing with 10,000 lb, for us this translates into
greater resistance to the development of play due to the higher strength
materials used. Shortly after this switch-out Lancair began offering
replacement bearings with a PTFE liner.
I also switched out
the rod end bearings in the main gear over center link in about '98 @ 200
hours for similar reasons. The original bearings had a bronze
race, the replacement is alloy steel - again with twice the load rating
(Aurora AM series).
Chris Zavatson
N91CZ
360std
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