M20K Alternator Coupling

[Jack Russell]

4 hours ago, takair said:

There are lots of discussions on this on the various forums (here and Beechtalk). One concern is the particles plugging the oil passages and not getting oil to the right spots.  I don’t know how to prove or disprove this.  The alignment of the gears is critical.  Not easy, but you can check the gear mesh pattern by looking at the gears.  Did you get 500 hours out of the first one or did it start after  a recent overhaul?  

Yes, it went well over 500 hours with no problems, until it became a bit slow to start charging after start up. The second one destroyed itself and potentially did serious engine damage after about 10 hours. Waddington Effect? 
In fairness, the component did need replacing but whether the act of maintaining or the materials used was the cause is yet to be determined. However, whatever happened to the manufacturers failure mode and effects analysis in approving such a vulnerable design?

[LANCECASPER]

3 hours ago, GeeBee said:

I am not an A&P but I did stay at a Holiday Inn Express last night.

As long as you didn't eat the breakfast you should be ok . .lol

[GeeBee]

54 minutes ago, Jack Russell said:

Yes, it went well over 500 hours with no problems, until it became a bit slow to start charging after start up. The second one destroyed itself and potentially did serious engine damage after about 10 hours. Waddington Effect? 
In fairness, the component did need replacing but whether the act of maintaining or the materials used was the cause is yet to be determined. However, whatever happened to the manufacturers failure mode and effects analysis in approving such a vulnerable design?

As far a Continental couplers and installation go here is my rules.

I never use rebuilt couplers, only new. Had too many failures of rebuilt units. Why, I don't know but never had good luck there. New is twice the cost but infinitely more reliability IMHO.

I always observe the installation of both the coupler and the alternator with the SB's in hand. It seems like an easy task, but it can messed up really easily especially by the inexperienced.

Finally, if you encounter a charging problem with a direct drive alternator, land immediately and check it out. Too much can go wrong a bad coupling (as you now know). 

[Steve Dawson]

After just one year and approximately 70 hours the coupling from my 231 just stopped working again. I don't want to get another rebuilt one from Spruce and have this happen again. Does anyone know where is the best source to get a new one quickly and how to check for quality? 

[jetdriven]

If it comes from Kelly Aerospace or Hartzell, it ain’t gonna be quality.. that’s one thing to think about. 

[shawnd]

On 11/19/2023 at 11:37 AM, GeeBee said:

As far a Continental couplers and installation go here is my rules.

I never use rebuilt couplers, only new. Had too many failures of rebuilt units. Why, I don't know but never had good luck there. New is twice the cost but infinitely more reliability IMHO.

I will second this. Had 2 alternator failures on rebuilt units within a span of 6 months - third time went with new. Agree with cost, but peace of mind is priceless. 

[shawnd]

On 8/26/2024 at 6:16 AM, jetdriven said:

If it comes from Kelly Aerospace or Hartzell, it ain’t gonna be quality.. that’s one thing to think about. 

Who else manufactures these now? PlanePower is now owned by Hartzell.

[GeeBee]

I have a friend that runs a well known aviation electrical and avionics shop. He tells me he gets rebuilt couplers that fail the torque test, right out of the box.