"Corky Scott" wrote in message
...
On Wed, 20 Jul 2005 09:05:52 -0400, Corky Scott
wrote:

Rich, if it isn't, how do you fix that? I've heard this a lot and it
makes sense that you want the prop tracking properly, but how do you
do it?

Nevermind Rich, jls answered the question.

Corky Scott


To find the prop's track, I stand a stool or small ladder as close to the
tip as possible, first fore, then aft of the prop's circumference. You
pull the prop through with all wheels tightly chocked and the top plugs
removed. When the prop is tracked properly, both tips will track the same
cat's hair -- in the direction of the longitudinal axis of the aircraft--
from the edge of the stool, or whatever makeshift pointer you may erect for
the purpose, like for example a screwdriver tip or ice pick c-clamped to a
small stepladder. You can also find if the prop blades are same length
too.* Do it in the hangar, not outside in the wind.

Sometimes a crankshaft flange out of limits will throw you when the prop may
be OK. I've seen it and done a lot of head-scratching until we did a runout
on the steel flange. There are prop-struck flanges out there with big
double-digit runouts on them, which of course you find with a good dial
indicator. 36 or so inches out to the tip and that flange slop is
magnified.


*We had an aircraft which had a pre-buy done, and the owner was upset to
hear his aluminum blades were unequal by a quarter inch. We set up a
pointer and showed him they were in fact dead nuts equal. Measuring helps
too, of course.

Pointers or dial indicators are also great for meticulous installation of a
spinner. There's nothing more obnoxious than a spinner wobbling like hell
while the engine idles.

Yesterday at KFQD I saw the world's most beautiful 1946 Globe Swift. That
thing was a joy to behold and when the 6-cylinder IO-360 Continental engine
sprang into motion, the polished aluminum spinner tracked to the naked eye
like it had been put on using a dial indicator. It is said you can buy that
aircraft for something in excess of 100k. See Van Van der Ploeg in
Greenville, SC.