Vibrations

[Mark Keneston]

Sensenich doesn't make a metal ground adjustable prop, but I understand what your trying to say

Glenn

That's right its composite. So as I was saying..... see this previous post. Bolts???? Did it have one previously?

I am going to throw this out there for feedback

I have the Sensenich Composite Ground adjustable prop on my Sport Cub. I have around 900 hrs on this prop. I absolutely love the enhanced performance and the immediate thrust this prop provides especially in STOL situations.

I discovered a broken prop hub bolt at around 450 hrs m/l of use and just recently discovered another broken bolt at around 900 hrs m/l of use. It is actually the same hole.

In the beginning I gradually picked up a vibration, after the bolt broke and Sensenich rebuilt the hubs when the vibration started to develop again I had the prop balanced successfully, however after awhile the vibration started again.When I had 7AK down to catch up on all the CC bulletins last Summer I sent the prop and hub back to Sensenich and they graciously rebuilt the prop and hubs at no charge! No vibration for the first 50 hrs after the rebuild but now I have a vibration along with finding a broken hub bolt again. I had the bolt extracted by a machine shop and re-installed the hub and prop; test flew it and still have a vibration.

During the time between 450 hrs of use and 700 hrs I had multiple mag issues i.e. broken shaft, spring broken, parts coming loose etc. There was some rumor of the vibration from this prop on other sport cubs possibly causing mag problems.

I also have had some apparent cartridge wear, don't know yet if that has effected performance or not.

Sensenich have very responsive to my issues and supportive. They are working on the issues.

What I am looking for is information to provide them and me to see if any of you other comp prop users have had similar or any other issues?

[chipallen]

Mark,

I've owned a couple of Sport Cubs with Sensenich composite, ground-adjustable props and Bendix mags. Several years ago, at Oshkosh, a few of us met with Sensenich and Continental (TCM) to discuss the ongoing problems; broken mag shafts, prop vibration, etc. Both of my Sport Cubs had several instances of broken prop bolts, broken mag drive shafts, etc. Originally, we thought the vibrations were simply propeller related, but after the prop bolts began breaking, Sensenich rebuilt the hub (no charge), and things returned to normal. At the time, Continental claimed that the Sensenich composite prop (and it's inherent lack of mass) in conjunction with the Bendix mags were setting up a harmonic vibration than eventually took out the magneto. Based on a lot of telephone conversations with Sensenich and TCM engineering, it was determined that there are two solutions to this problem. First, get rid of the composite, ground-adjustable prop and install a metal prop, or get rid of the Bendix mags and go to Slicks. I changed the mags out on my second Sport Cub and the mag issues went away as did the vibration. Flew it about 250 hours, sold it, and the current owner has had no problems at all. See the attached bulletin from Sensenich.
Sensenich Harmonics.pdf

[Mark Keneston]

Mark,

I've owned a couple of Sport Cubs with Sensenich composite, ground-adjustable props and Bendix mags. Several years ago, at Oshkosh, a few of us met with Sensenich and Continental (TCM) to discuss the ongoing problems; broken mag shafts, prop vibration, etc. Both of my Sport Cubs had several instances of broken prop bolts, broken mag drive shafts, etc. Originally, we thought the vibrations were simply propeller related, but after the prop bolts began breaking, Sensenich rebuilt the hub (no charge), and things returned to normal. At the time, Continental claimed that the Sensenich composite prop (and it's inherent lack of mass) in conjunction with the Bendix mags were setting up a harmonic vibration than eventually took out the magneto. Based on a lot of telephone conversations with Sensenich and TCM engineering, it was determined that there are two solutions to this problem. First, get rid of the composite, ground-adjustable prop and install a metal prop, or get rid of the Bendix mags and go to Slicks. I changed the mags out on my second Sport Cub and the mag issues went away as did the vibration. Flew it about 250 hours, sold it, and the current owner has had no problems at all. See the attached bulletin from Sensenich.
Sensenich Harmonics.pdf

Chip

LBlack here will appreciate that info for sure. Maybe he had the composite on prior and damaged the mags??? MK

[chipallen]

Chip

LBlack here will appreciate that info for sure. Maybe he had the composite on prior and damaged the mags??? MK

From several years ago, I'm not aware of any magneto failures on Sport Cubs that were running aluminum props. I think they all had the "infamous" Sensenich composite / Bendix mag combination.

[LBlack]

From several years ago, I'm not aware of any magneto failures on Sport Cubs that were running aluminum props. I think they all had the "infamous" Sensenich composite / Bendix mag combination.

Thanks for all your helpful comments. Our 2007 Sport Cub was delivered to the original owner with the Sensenich wood prop. At 104 hrs, I was replaced with the Sensenich ground adjustable composite prop. Then at 234 hrs, the wood one was reinstalled. The plane has Bendix mags.

We plan to inspect the mags as the result of your comments.

Thanks again.

[Cubdriver2]

I bought my Sensenich GA prop used off of a Legend Cub and put it on my EX 0200 Cub with slick mags. Before I bought it I did some research and couldn't find any Slick 0200 problems with the prop. Now have 300+ hrs on it and love it. I carry a torque wrench and do 5 minute pitch changes in the field on long trips to go from cruise to climb.

Glenn

[cityrancher]

I have been running the Sensenich ground adjustable composite on an XP mod Sportcub for 350 hours now with no problems. I do have Slick mags.

[chipallen]

All confirms what I have learned over the years. Slick mags don't have the mag drive / vibration issues of the Bendix / TCM mags.

[LBlack]

Still working on the subject vibration issue on a 2007 Sport Cub swinging the original equipment Sensenich wood prop. Have done some maintenance over the past few weeks - replaced motor mounts, checked prop indexing, inspected and timed the Bendix mags for internal damage (Sensenich GA composite was on plane for about 4 years or 130 hrs). Wood prop storage conditions for the 4 years it was not used unknown.

Vibration remains.

Any thoughts or ideas on this issue and the Sensenich wood prop experience would be very helpful.

[Mark Keneston]

Still working on the subject vibration issue on a 2007 Sport Cub swinging the original equipment Sensenich wood prop. Have done some maintenance over the past few weeks - replaced motor mounts, checked prop indexing, inspected and timed the Bendix mags for internal damage (Sensenich GA composite was on plane for about 4 years or 130 hrs). Wood prop storage conditions for the 4 years it was not used unknown.

Vibration remains.

Any thoughts or ideas on this issue and the Sensenich wood prop experience would be very helpful.

Same from me. See if you can borrow a set from an A/P or a friends plane and just test before you invest. You might smile. MK