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Alternator failure M20K 231

tomatl

By tomatl
in Modern Mooney Discussion

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tomatl Contributor

tomatl

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Here are some pictures of the alternator that is installed in the airplane. It is still not clear to me (or the mechanic) where the polymerized coupling is that may start to slip. Maybe I am slow, but could someone please explain. Thanks!


47a3c6d5ed91459f2b2f901e9200be39.jpg

0def99a3e629c4faaee356030b0006af.jpg


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Geoff Proficient

Geoff

Posted
Posted
On 7/22/2020 at 8:51 AM, jlunseth said:

carusoam is right, takeoff with the Master off is definitely not recommended, I should be more clear. In the 231, setting the power on takeoff and then for cruise is too tricky, with the possibility of overboosting or overheating the engine. If you are aloft and in stable, cruise flight, so the engine is set up safely, then switching the Master off to save power for landing operations is a good choice. 

Here is a coupler (no bushing). If the coupler has gotten damaged the replacement is more expensive, there is usually a credit for return of the old part if it can be refurbished:

315674E1-1401-493D-925B-A207337E0955.jpeg

487AA165-A75A-4E77-96B3-59B33AEDC263.jpeg

These are pictures of the polymerized clutch.  It is the black rubber inside the metal housing.  If memory serves, the clutch replacement does not include the gear.  I don't see this part in the picture you posted.  Focus on the small gear in your picture and anything attached that is/was attached to it.

To my knowledge all TSIO 360 GB/LB engines use a gear driven alternator with this clutch arrangement.  Has your engine been modified in any way?  Check the logbooks?

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tomatl Contributor

tomatl

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These are pictures of the polymerized clutch.  It is the black rubber inside the metal housing.  If memory serves, the clutch replacement does not include the gear.  I don't see this part in the picture you posted.  Focus on the small gear in your picture and anything attached that is/was attached to it.
To my knowledge all TSIO 360 GB/LB engines use a gear driven alternator with this clutch arrangement.  Has your engine been modified in any way?  Check the logbooks?

These were all the parts that where on the drive. The small gear, as much as I (or the mechanic) could see, did not have a polymerized part or surface to it.


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carusoam Grand Master

carusoam

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Expect any direct drive alternator to have a rubber drive to separate it from the engine in the event of failure...

The alternator shaft is pretty short... but that is the part that gets the clutch....

If it is not on the alternator’s shaft, check the engine where it is mounted...

I think Clarence has posted pics of where the clutch gets mounted, and what to look for on Continental engines...
 

Since you have everything apart... now would be the time to put a new on on there..? 
 

PP thoughts only, not a mechanic...

Best regards,

-a-

 

tomatl Contributor

tomatl

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Seems to best option is to get all new/refurbished coupling and let the mechanic deal with it. When taking the alternator off, another problem emerged. Some of the safety wires inside the engine appear to be broken and need to be replaced. (The engine itself has no sign of problems.) Anyone an idea of what could have caused that?

70047a0989af9cf85077d6328b572a86.jpg


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Guest

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Posted
Posted
10 hours ago, tomatl said:

Here are some pictures of the alternator that is installed in the airplane. It is still not clear to me (or the mechanic) where the polymerized coupling is that may start to slip. Maybe I am slow, but could someone please explain. Thanks!


47a3c6d5ed91459f2b2f901e9200be39.jpg

0def99a3e629c4faaee356030b0006af.jpg


Sent from my iPhone using Tapatalk

This is the older style drive coupling with 2 rubber drive cushions retained in the metal cup which fits between the tabs on the drive member which is still on the alternator drive shaft.

Clarence

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Guest

Posted
Posted (edited)
6 hours ago, tomatl said:

Seems to best option is to get all new/refurbished coupling and let the mechanic deal with it. When taking the alternator off, another problem emerged. Some of the safety wires inside the engine appear to be broken and need to be replaced. (The engine itself has no sign of problems.) Anyone an idea of what could have caused that?

70047a0989af9cf85077d6328b572a86.jpg


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That gear is attached to the camshaft with four bolts per the IPC.  I have to go the the engine maintenance manual for installation instructions.

Clarence

F90F18BC-4FD6-4F7D-8D3F-9E15E1DB0CF9.jpeg

Edited by M20Doc
carusoam Grand Master

carusoam

Posted
Posted

I got it partially right, partially described the newer version that IO550s use... :)
 

Try to visualize the bits and pieces...

Essentially it is (sometimes) a break-away design. Used to keep expensive things from self destructing...

When it is a breakaway design, it may be called a clutch...

Rubber drive dogs are typical for this type of function...

The rubber dogs get held, captured Between more durable parts...

Using color codes, I pointed at things that may help with the visualization...

Blue arrows... rubber drive dogs....vibration absorbers...

Red arrows... the solid metal that does the driving....

Yellow arrows... the solid channel that the drive assembly fits in...

Green arrow... the cover that houses the dogs and drive...

All of this stuff goes on the shaft in order... it gets held in place by a nut on the end of the shaft... follow the procedures/drawings outlined by M20Doc...

And... by the look of it... (of a casual observer)... I don’t see the break-away nature of this particular device... :)

It may have been used for keeping vibrations from transferring from the engine to the alternator...(?)

MS is a bunch of team work...

Great pics...

Great support documents...

Great discussion...

PP thoughts only, I am not a mechanic....  :)
 

Best regards,

-a-

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Warren Rising Star

Warren

Posted
Posted

Helping a friend troubleshoot a similar issue in a 231.  Recent engine rebuild and alternator rebuild.  We found the cooling line was not reinstalled and are hoping the  intermittent issues are heat related.  Next step is to reinstall cooling line.

tomatl Contributor

tomatl

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Helping a friend troubleshoot a similar issue in a 231.  Recent engine rebuild and alternator rebuild.  We found the cooling line was not reinstalled and are hoping the  intermittent issues are heat related.  Next step is to reinstall cooling line.

Can you elaborate which "cooling line" you are referring to.


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Warren Rising Star

Warren

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12 hours ago, tomatl said:

Can you elaborate which "cooling line" you are referring to.

There should be a scat hose from the rear baffle to a plastic cover on the alternator that directs fresh air from the upper plenum to the alternator.  My 1985 M20k has this line, his 1979 M20K has the fitting on the baffle and the plastic cover on the alternator but no line connected.

Hope that helps.  If you Still have questions, PM me and I will take a picture tomorrow.

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tomatl Contributor

tomatl

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There should be a scat hose from the rear baffle to a plastic cover on the alternator that directs fresh air from the upper plenum to the alternator.  My 1985 M20k has this line, his 1979 M20K has the fitting on the baffle and the plastic cover on the alternator but no line connected.
Hope that helps.  If you Still have questions, PM me and I will take a picture tomorrow.

Thanks, I‘ll check with the shop. A picture would be great.


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Warren Rising Star

Warren

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Sorry. I took pictures and completely forgot to post them.

First picture is the cooling line from the baffle to the alternator.

Second picture is the inlet for the hose from the front side.

Third picture is the hose connection to the cooling shroud on the air inlet for the alternator.

 

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38845125-1267-4BA1-B2AE-743B894CE9F0.jpeg

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tomatl Contributor

tomatl

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Sorry. I took pictures and completely forgot to post them.
First picture is the cooling line from the baffle to the alternator.
Second picture is the inlet for the hose from the front side.
Third picture is the hose connection to the cooling shroud on the air inlet for the alternator.
 
B168AAA9-A7CF-42E1-B461-E75890AE8D9A.jpeg.dad2dec42a4333912dfd072e9f0a6e5b.jpeg
2BF4C32A-BE2B-43F3-83E4-20011219FA89.jpeg.5e74d1d4c310f7c5d8331b6de3aad92f.jpeg
38845125-1267-4BA1-B2AE-743B894CE9F0.jpeg.469e66970ed2812f39be23bd4fc820be.jpeg

Thanks,
I'll share it with the mechanics. Mine does currently not have any cooling line like this going to the alternator.
Best,
Tom


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Warren Rising Star

Warren

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6 hours ago, tomatl said:


Thanks,
I'll share it with the mechanics. Mine does currently not have any cooling line like this going to the alternator.
Best,
Tom


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Good luck. Maybe you will be lucky enough to just need a piece of SCAT tubing. 

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