Prop Blade Wiggles on C182

A local pilot called me with a preflight issue of a propeller blade on
C182 being a bit loose in its socket. Holding the blade tip, he could
wiggle it front to back and twist it slightly, changing its pitch.
Some mechanics told him it was safe to fly home.

Anyone disagree?

Greg Esres wrote:
A local pilot called me with a preflight issue of a propeller blade on
C182 being a bit loose in its socket. Holding the blade tip, he could
wiggle it front to back and twist it slightly, changing its pitch.
Some mechanics told him it was safe to fly home.

Anyone disagree?

This is normal (to a degree). McCauley calls it "Blade Shake", and is a
result of the fit of the blade root in to the hub bearing. Statically,
there will be some "slop" (up to 1/8" at the tip is acceptable), but
under rotational loads, this "slop" will disappear.

Happy Flying!
Scott Skylane
N92054

On Fri, 21 Apr 2006 22:25:07 -0800, Scott Skylane wrote:

This is normal (to a degree). McCauley calls it "Blade Shake", and is a
result of the fit of the blade root in to the hub bearing. Statically,
there will be some "slop" (up to 1/8" at the tip is acceptable), but
under rotational loads, this "slop" will disappear.

This is ONLY normal for variable pitch propellers.

And even then, we are talking measurements that are barely perceptible to
the human eye. I personally would not have flown that plane without it
being further checked into.

Having been through replacing the front bulkhead (cracked due to unbalanced
prop) and overhauling the spinner due to an unbalance prop, I learned that
balancing is down to a .10 of a gram so there is some serious precision in
the art of the propeller. Prop only has 2400 hours on it (total airframe
time is the same).

Having seen what it took to get my bird back into specs, blade shake would
make me question whether there was a problem more then just the propeller
since we are only talking .125 of an inch.

See http://www.mccauley.textron.com/svcl.../sl1989-2C.pdf for
specific details regarding blade shake.

Allen

In article ,
A Lieberman wrote:
Having seen what it took to get my bird back into specs, blade shake would
make me question whether there was a problem more then just the propeller
since we are only talking .125 of an inch.

See http://www.mccauley.textron.com/svcl.../sl1989-2C.pdf for
specific details regarding blade shake.


The original poster didn't quantify the movements of the propeller, but
based on the document quoted, I don't see any cause for concern unless
the propeller movements were far in excess of the recommendation. The
bottom line is that some shake and twist are normal, but a propeller
blade that is excessively "loose" in the hub is not normal.

Balance is an entirely different issue.



JKG

My Aviat Husky' Lycoming 0-360 with a Hartzell constant speed prop
always has 1/8"-1/4" play front to back coming from the crankshaft I
think. It always seem a little excessive, compared to others, but never
was a problem. Engine and prop is beyond TBO and still going strong....

Fore and aft crankshaft play is the engine's thrust bearing clearance and
play is normal. It may seem like 1/4 inch but actually is less.

Kent Felkins
Tulsa



"Doug" wrote in message
ups.com...
My Aviat Husky' Lycoming 0-360 with a Hartzell constant speed prop
always has 1/8"-1/4" play front to back coming from the crankshaft I
think. It always seem a little excessive, compared to others, but never
was a problem. Engine and prop is beyond TBO and still going strong....



*** Posted via a free Usenet account from http://www.teranews.com ***

A Lieberman wrote:

This is ONLY normal for variable pitch propellers.

Uhh, yeah...I'd think so. **Fixed-pitch** props are solid pieces of
aluminum, tip to tip. NOT GOOD if one of those shows some "play".

This is normal (to a degree). McCauley calls it "Blade Shake",

Thanks for the info. The pilot in question was always in the habit of
tugging on the prop during his preflight, so this wiggle was new. I
don't know how much movement it displayed.

About an 1/8" fore and aft, and a degree or two of twist is what my has
had for
about 20 years. Due to centrifical force, the blade seats against its
retention collar when
it is spinning...

Due to centrifical force, the blade seats against its
retention collar when it is spinning...

Thanks; I'll feed this to the pilot for what normal is.