|
|
Blue
On Jul 28, 2013, at 3:29 PM, Paul Miller wrote: Agreed, I wouldn't have the nerve to pitch that to hartzell and mr brown. They are not fly by nights at hartzell. The issue is whether a common problem exists. I think Hartzell system wide manufacturing defect can be safely moved to low priority. Hartzell does a thorough vibration analysis on engine prop combinations so I don't see how something new cropped up there.
Lyc had the crankshaft issue on the Malibu, I don't recall it being related to prop at all.
I think it is a mistake to look for hartzell 550 combination as being a factor in vibration since the sample is largely hartzell and 550. You need some other way to differentiate between vibrating and non vibrating installations. I can safely say that if I found 20 contact points in the legacy over the last four years I would be cataloging those points first and confirming they are not in play. Once those are ruled out then you have something to work with. A database of 550s with and without problems may not go very far to getting a resolution. Of course not. But it will establish a couple basic facts and identify a group of people interested in drilling deeper. In the meantime, do you want to publish your list of 20 contact points?
Paul
WHAT? That makes no sense at all. Where did you ever get such an idea? Danny LNC2-360 Mk-II Nothing is foolproof to the sufficiently talented fool. It could be possible for wear or manufacturing process to allow one blade to have more play in pitch operation than the others.
Blue Skies, How is that mechanically possible? All blades are attached to the same pitch change mechanisms Elton That is a possibility I had not considered, I will ask Hartzell about it. Another possibility is the movable crankshaft counter weights failing to position correctly.
Steve Colwell
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 bite of air and then causing everything to wobble. It settles in sometimes but when you change the power setting the pitch on the prop is adjusted by the hub unevenly.
Blue Skies,
Craig Schulze
Lancair N73S
On Jul 25, 2013, at 1:22 PM, "Steve Colwell" <mcmess1919@yahoo.com> wrote:
In the first 40 hours I had vibration so severe 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 section of the nose gear door.
At about 50 hours I paid Barrett to tear down the engine to replace the
Performance pistons (prematurely worn top rings) with stock ECI pistons.
Also found a cracked case.
We had the Kelly Alternator balanced and rebuilt at a shop recommended by
Bill Bainbridge of B & C. Sorry I can't remember the name, the Legacy file
is in Texas.
I rounded the leading edges of the elevator counter weights when building so
I temporarily squared them off to go back to the stock shape for testing.
All gear doors were checked in flight with 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 twice.
I could not get more that the usual vibration (which always seemed to be too
much) on test flights. Then, unpredictably, vibration magnitude would
increase with power reduction on some later flight. I say unpredictably
because I could not get increased vibration by attempting to duplicate
previous conditions. Let's hope a solution surfaces at Airventure.
Steve Colwell Legacy RG IO550-N with Hartzell 3 Blade
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Paul
Miller
Sent: Thursday, July 25, 2013 7:22 AM
To: lml@lancaironline.net
Subject: [LML] Re: Potential Problem-Engine Vibration
Ed Martin's legacy is smooth. Mine has had a lot of annoying vibes as you
describe but virtually all have been removed with lots of cowling
interference fixes and plug change. Many pilots forget the alternator can
be a wicked source of vibration and it is almost in the same plane as the
prop.
The problems I had originally were in that freq range and visible at the
wingtip also.
Paul
|
|