Identifying the Source of a Vibration

[Marauder]

I'll get some better pictures this week of what the clearance looks like.






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[smwash02]

Yeah, it looks pretty low from here. Get 'em ordered!

[carusoam]

For a quick comparison...

see the distance from the top cowl to the starter ring of a nearby Mooney C,D,E,F,G variety...  

it appears that the engine has moved a bit south for the winter?

It would have been a great opportunity to do one of those cowl projects.  Might be a great opportunity to collect some data for David's F project..?

Thinking out loud, spending M's Money, working on some multi-tasking skills, and forwarding David's cowl project at the same time

Best regards,

-a-

Edited January 24, 2017 by carusoam

[Marauder]

For a quick comparison...
see the distance from the top cowl to the starter ring of a nearby Mooney C,D,E,F,G variety...  
it appears that the engine has moved a bit south for the winter?
It would have been a great opportunity to do one of those cowl projects.  Might be a great opportunity to collect some data for David's F project..?
Thinking out loud, spending M's Money, working on some multi-tasking skills, and forwarding David's cowl project at the same time
Best regards,
-a-

You really know how to hurt a guy Anthony! I would love to do David's cowl mod.


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[N6758N]

9 hours ago, Marauder said:

I have no where near that clearance. I can't even see the starter Bendix. Thanks for posting these.

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The clearance also has much to do with who installed your cowl mod...No two will be the same. Mine is much more similar to Marauders because that is how I wanted it to be when I installed it. 

[Marauder]

The clearance also has much to do with who installed your cowl mod...No two will be the same. Mine is much more similar to Marauders because that is how I wanted it to be when I installed it. 

Matheison installed mine.


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[bonal]

5 hours ago, N6758N said:

The clearance also has much to do with who installed your cowl mod...No two will be the same. Mine is much more similar to Marauders because that is how I wanted it to be when I installed it. 

And so Mr. 26 the only pics that will matter is of your F before and current. 

[rbridges]

21 hours ago, Marauder said:

 

Rich -- that is one thing I am concerned with. The nick on the lower cowl enclosure is fairly recent. So it may be very well an engine mount. Can you tell by looking at a mount that something is amiss?


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When I changed my Lord mounts, I couldn't tell anything was wrong until they were removed.  One had a good sized tear.  Honestly couldn't say I felt any difference in the way the plane flew/felt or saw any changes in the prop height.

Have you given any more thoughts to the prop balancing?  How do your blades look?  How does it feel if you do a high run up on the ground?

[N6758N]

27 minutes ago, bonal said:

And so Mr. 26 the only pics that will matter is of your F before and current. 

Yup!

 

[N6758N]

5 hours ago, Marauder said:

 

Matheison installed mine.


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Chris,

If you go out to the hangar after work and pull the cheek cowls on the sides you should be able to get a decent look at the mounts and check them out. Feel free to send some pics to my cell if you want. Or upload them on here and get everyone else opinion... 

[Marauder]

Chris,
If you go out to the hangar after work and pull the cheek cowls on the sides you should be able to get a decent look at the mounts and check them out. Feel free to send some pics to my cell if you want. Or upload them on here and get everyone else opinion... 

I'm headed there now. Inquiring minds want to know. I will snap some pics of everything. Including your wiring job LOL!


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[N6758N]

Here are the only two pics I have of your bird, doesn't help much here...Always loved our matching paint 

 

[Marauder]

When I changed my Lord mounts, I couldn't tell anything was wrong until they were removed.  One had a good sized tear.  Honestly couldn't say I felt any difference in the way the plane flew/felt or saw any changes in the prop height.
Have you given any more thoughts to the prop balancing?  How do your blades look?  How does it feel if you do a high run up on the ground?

The blades are fine. No noticeable chunks missing although my new hangar location has me cross some areas with fine stones and I am seeing some pitting on the back of the blades.

The prop was balanced years ago. It was a very smooth running 4 banger until recently. Something changed.

On the ground I don't feel anything different during the runups. I noticed it for the first time doing a climb out. There was a seat vibration I never noticed before. One of my safety pilots also made a comment about the seat vibration on a missed. So I know it wasn't just my seat.

At cruise, it just feels different.


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[Browncbr1]

when is the last time you soaked your injectors in hobbs?

[N6758N]

15 minutes ago, Browncbr1 said:

when is the last time you soaked your injectors in hobbs?

Did you mean Hoppe's #9? If he had dirty injectors he would be seeing irregular CHTs and EGTs. 

[Guitarmaster]

Chris,

Does the vibration change with RPM?  It sounds like it was a sudden onset?  Try pulling the prop back to 1900 RPM while in cruise; see what kind of difference there is.  I have run mine at 24"/1900 per Mike Busch and found it odd, but nice.  The plane sounds like a turboprop.  Try to notice if there is any RPM where the vibration is less.  At 1900RPM I experienced a low frequency, low intensity vibration.  I asked Mike about this and he seemed to think it because the harmonic balancer is set up for higher RPM.  

It does sound like the engine is touching something hard.  I would definitely be looking for evidence of that.  

[Marauder]

Here are the only two pics I have of your bird, doesn't help much here...Always loved our matching paint 
 

Ah yes, I remember those photos. It was where I left another large chunk of money on someone's night stand.




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[Marauder]

when is the last time you soaked your injectors in hobbs?

I used to clean them every 100 hours until someone told me to stop. The SavvyAnalysis report came back (thanks Paul) and confirmed that my engine is performing consistently with the way it did before the vibration started.


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[Marauder]

Chris,

Does the vibration change with RPM?  It sounds like it was a sudden onset?  Try pulling the prop back to 1900 RPM while in cruise; see what kind of difference there is.  I have run mine at 24"/1900 per Mike Busch and found it odd, but nice.  The plane sounds like a turboprop.  Try to notice if there is any RPM where the vibration is less.  At 1900RPM I experienced a low frequency, low intensity vibration.  I asked Mike about this and he seemed to think it because the harmonic balancer is set up for higher RPM.  

It does sound like the engine is touching something hard.  I would definitely be looking for evidence of that.  

I usually fly in between the top of the red arc (2350 RPM) and 2500. It is noticeable at those RPMs. I will try the lower RPM.

I just snapped a lot of pictures. Will post them when I get to my laptop. I really now think my mounts have something to do with it. The sign for me was the ram air boot. Looks like it is stretched. I just had it replaced at the last annual.


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[bonal]

Marauder, I'm suprised that with all that fancy glass and monitors you have installed there isnt a setting on your screen that says your new vibration is being caused by (fill in the blank) you might check there might be just such a read out.  Once after an annual on my 150 I noticed a different feel and sound and it turned out the air intake was just a little off alignment and was touching the cowl. I noticed it right away. trust your senses there is something not right.

[Marauder]

Ok, some pictures for the collective group to do what you do best. 

Cowl pictures:

You can see a tight clearance and even signs of some rubbing.

A nick:

Full cowl picture

Pictures of the mounts. Anyone see something obvious?

Pilot side upper:

Pilot side lower mount

Copilot upper mount:

Copilot lower mount:

Now for the troubling photo. I do not remember the angle of the ram air boot being this sharp. I look at the boot often since I have purchased 3 or 4 over the 26 years of ownership. I had the boot replaced this past June for tears starting. If the engine was sagging I would have expected the opposite.

[N6758N]

At first glance it doesn't look like you mounts are that out of shape, interesting. I do find the sharp angle of your intake boot out of place though. 

[Guitarmaster]

1 hour ago, Marauder said:

Ok, some pictures for the collective group to do what you do best. 

Cowl pictures:

You can see a tight clearance and even signs of some rubbing.

A nick:

Full cowl picture

Pictures of the mounts. Anyone see something obvious?

Pilot side upper:

Pilot side lower mount

Copilot upper mount:

Copilot lower mount:

Now for the troubling photo. I do not remember the angle of the ram air boot being this sharp. I look at the boot often since I have purchased 3 or 4 over the 26 years of ownership. I had the boot replaced this past June for tears starting. If the engine was sagging I would have expected the opposite.

Since we have sister ships, I will get some pictures of mine tomorrow for you to compare.

I don't think my boot sits at such a sharp angle.  Could be wrong though.

Edited January 25, 2017 by Guitarmaster

[cctsurf]

15 minutes ago, Guitarmaster said:

 

15 minutes ago, Guitarmaster said:

I would say that it is definitely the engine drooping on the mounts.  You will either need to shim it up (according to LASAR's specifications) or replace the motor mounts or both.  BTW, getting your engine square with the world is a great speed mod, it adds a couple of mph and no STC required.  Right now your engine is pulling you down, not a good thing for an airplane that is supposed to be going up.

[Andy95W]

It's just strange that it happened rather quickly over a relatively short period of time.  

Is the new vibration more of a low-pitch, or high-pitch variety?  If it was low pitch, I would assume engine mounts had grown old and hard.  If more of a high pitch, I would assume they were sagging and your engine was now contacting something it didn't used to contact.

But none of that explains the odd angle for your intake boot.

Good luck, Chris.