Looking at a J model with saggy motor mounts?

[EricJ]

I'm looking at purchasing a J model that has a saggy motor very similar to this one (but not this one, which was discussed in another thread):

https://www.aso.com/listings/spec/ViewAd.aspx?id=163471

The symptom being the spinner not lining up with the cowling very well.   In the previous thread there was opinion expressed that this was due to the motor mounts sagging or just needing to be replaced.

On the particular aircraft that I'm looking at the motor mounts were replaced coincident with a prop-strike-related tear down about thirty hours ago, but the spinner doesn't line up with the cowl just like in the pics in the link above. Is this likely due to just a crappy installation, poor quality mounts, or is it possible that the motor mount frame itself was tweaked during the prop strike?    The prop strike was the result of porpoising during a bad landing.

 

 

 

 

[rbridges]

it could be the motor mounts, but 30 hours isn't very long depending on when it was done.  I'm guessing it needs to be shimmed.  

 

http://www.donmaxwell.com/publications/MAPA_TEXT/Alining Engine Using Shims/ALIGNING_YOUR_ENGINE.HTM

[Hank]

My thoughts, too, Rob.

[mooniac15u]

The fiberglass cowls on J's also tend to ride up out of alignment.  As the edges of the cowl and the fastener holes wear the air pressure tends to push up on the cowl.  @jetdriven came up with a solution to help prevent this issue.

[KSMooniac]

If I were serious about that plane, I'd R&R the cowl, then check the alignment. Very likely due to missing shims as outlined in Don's article above. My '77 cowl is worn and rides up after reinstallation. It just takes some effort to fix it, which I haven't done yet.

 

 

Hopefully the mount was inspected after the prop strike, so verify. Likely you're just looking at missing shims and a worn cowl, though.

Sent from my LG-LS997 using Tapatalk

 

 

 

 

[EricJ]

That's all very helpful.    The IA had indicated he wasn't a fan of reshimming mounts, but sounds like it's SOP with a Mooney.

Thanks everybody for the input.

[Joe Larussa]

2 hours ago, mooniac15u said:

The fiberglass cowls on J's also tend to ride up out of alignment.  As the edges of the cowl and the fastener holes wear the air pressure tends to push up on the cowl.  @jetdriven came up with a solution to help prevent this issue.

He has a solution for this? Do tell!

[mooniac15u]

13 minutes ago, Joe Larussa said:

He has a solution for this? Do tell!

 

[jetdriven]

that guy has way too much time on his hands

here is the finished product. Its been painted a year now.

 

Edited March 1, 2017 by jetdriven

[Bob_Belville]

7 hours ago, EricJ said:

That's all very helpful.    The IA had indicated he wasn't a fan of reshimming mounts, but sounds like it's SOP with a Mooney.

Thanks everybody for the input.

We've moved shims more than once to improve spinner/cowl alignment. No big deal. Should take less than one hour.  

[Loogie]

Most M20Js came out of the factory with shims.  That is how they got a perfect alignment with the cowl.  Lots of IAs that don't have mooney experience think that way.  A little proper research will show them that in most cases shims will be required.  There is tech data that says how wide and how much is allowed etc.  After the MOH on my engine shims were required to make it align perfectly and that was with new mount discs.  An IA that says he is "not a fan" about a procedure is not properly informed, I would challenge his thought process and find out factual data about why shims are not good.  I venture to say there is none...

[carusoam]

Eric,

I think something got lost in translation...

1) Good engine mounts (rubber donuts) get shimmed to begin with...

2) Bad/worn engine mounts often get tossed during engine work... 

3) Adding shims to beef up worn engine mounts could be a bad idea if the mounts should have been replaced instead...

The new or shimmed donuts will be clearly indicated in the Log Books.  Read them for your own piece of mind.

While you are in there read the logs to see what was done to repair the prop strike.  Lycoming has posted some new rules regarding what a strike is and what should be done afterwards, in the last five years or so...

If the log book only says ground the blades and repainted them... ask for more details about the event...?

the second picture on the link provided shows the prop appearing to hang low and the door doesn't seem to close properly either...  well aligned J spinners really are smooth with the cowl.

Got any HD pictures of the plane you are looking at? Compare to the ones posted around here...

PP thoughts only, not a mechanic.

Best regards,

-a-

Edited March 5, 2017 by carusoam

[EricJ]

To clarify, the mounts were replaced coincident with an engine tear-down after the prop strike.   The mounts themselves look fine to me, i.e., they look like new rubber, no cracking, etc., so I suspect that the shop that did it just didn't bother to shim it for cowl alignment (they did some other funky stuff, too, that is being taken care of, so not getting that right isn't actually surprising).   The alignment is really the only issue, but I'd like it to be right for obvious reasons.    As mentioned, I think the IA is just not a fan of shimming bad or old mounts when they should be replaced instead, which doesn't seem to be the case here.

Should be able to post some pics later once the final status on the annual becomes clearer.   I'm waiting for some other issues with it to get resolved but it is taking some time.

[carusoam]

See if you can find the maintenance manual that explains how to shim the mounts/engine.

I suspect the shimming is done with the plane leveled on the ground.  It would be a bad idea to align it with the cowl that might not be currently in the right place...

I'm really stretching my tech skills here.  But I'm sure the maintenance manual has the procedure, and that procedure should have been followed.  Next question, who did the work?  Ordinary mechanic or MSC or equivalent...?  The log book will reference 'in accordance with' phrases that indicate a known procedure was followed...

Best regards,

-a-

Edited March 5, 2017 by carusoam

[EricJ]

The installation work was done at a (non-MSC) shop at the field where the prop strike took place, which was in a different state than the airplane was based.  Motor got sent out for tear down.  

[carusoam]

Does Scottsdale have an MSC?

might be a good idea to run this by them...

Pretty much a good PPI is in order to make sure these kind of things get covered...

Best regards,

-a-