It could be possible for wear or manuf= acturing process to allow one blade to have more play in pitch operation tha= n the others.

Blue Skies,

Craig Schulze

On Jul 27, 2013, at 5:36 PM, vtailjeff@aol.com wrote:

How is that mechanically possible? All blades are attached to the same pi= tch change mechanism.

J

Sent from my iPad

On Jul 27, 2013, at 12:34 PM, Steve Colwell <mcmess1919@yahoo.com> wrote:

That is a possibility I had not considered, I will ask Hartzell about it= . Another possibility is the movable crankshaft counter weights failin= g to position correctly.

Steve Colwell

= From: Craig Schulze <crai= g@skybolt.net>
To: Steve Colwell <mcmess1919@yaho= o.com>
Cc: "lml@lancaironline.net" <lml@lancaironline.net>
Sent: Friday, July 26, 2013 7:42 AM
Sub= ject: Re: Potential Problem-Engine Vibration

<= div class=3D"y_msg_container">
It sounds to me that you may have an issue= with your prop hub not changing the pitch exactly the same on all the= blades. The vibration you are feeling is one blade taking a larger bi= te of air and then causing everything to wobble. It settles in sometim= es but when you change the power setting the pitch on the prop is adjusted b= y the hub unevenly.

Blue Skies,
Craig Schulze
Lancair N7= 3S

On Jul 25, 2013, at 1:22 PM, "Steve Colwell" <mcmess191= 9@yahoo.com> wrote:

In the first 40 hours I had vibration so s= evere it caused stick shake. This
has continued intermittently more= or less for almost 400 hours.

First I found and fixed several Cowl Interference locations, then adjusted
and notched the hat s= ection of the nose gear door.

At about 50 hours I paid Barrett to tea= r down the engine to replace the
Performance pistons (prematurely worn to= p rings) with stock ECI pistons.
Also found a cracked case.

We had= the Kelly Alternator balanced and rebuilt at a shop recommended by
Bill B= ainbridge of B & C. Sorry I can't remember the name, the Legacy fi= le
is in Texas.

I rounded the leading edges of the elevator count= er weights when building so
I temporarily squared them off to go back to t= he stock shape for testing.

All gear doors were checked in flight wit= h video camera.

The pitch trim hinge pin had play, I replaced it per= Chris Zavatson's web
page.

Along the way the prop was balanced tw= ice.

I could not get more that the usual vibration (which always seem= ed to be too
much) on test flights. Then, unpredictably, vibration magnitude would
increase with power reduction o= n some later flight. I say unpredictably
because I could not get in= creased vibration by attempting to duplicate
previous conditions. L= et's hope a solution surfaces at Airventure.

Steve Colwell Lega= cy RG IO550-N with Hartzell 3 Blade

-----Original Message----= -
From: Lancair Mailing List [mailto:lml@lancaironline.net] On B= ehalf Of Paul
Miller
Sent: Thursday, July 25, 2013 7:22 AM
To: lml@lancaironline.net
Subject: [LML] Re: Potential Problem-Engine V= ibration

Ed Martin's legacy is smooth. Mine has had a lot of an= noying vibes as you
describe but virtually all have been removed with lot= s of cowling
interference fixes and plug change. Many pilots forget the alternator can
be a wicked source of vibration and it i= s almost in the same plane as the
prop.

The problems I had origina= lly were in that freq range and visible at the
wingtip also.

Paul<= br>