Starter and Alternator Adapter Mx?

[Ragsf15e]

I haven’t dug into this with my mechanic yet because my engine only has 200 hours, but what are the maintenance requirements for the adapters on the starter and the alternator? I have the dual alternators, so one is belt driven, but I think the other one has an adapter into the engine. I would think there are maintenance requirements so those don’t come apart and cycle pieces through the engine? And the same with the starter?

[Falcon Man]

Hey Rags,

Here is the TCM Maintenance Manual for sparked engines:

https://pceonline.com/wp-content/uploads/2017/04/M-0standardpractice2017-01-15.pdf

I have assisted in annuals over the years and the only thing that ever was noted was an oil leak at the accessory case.

Jeff

 

[kortopates]

No, these are both entirely on condition although TCM does have recommendations for scheduled alternator maintenance. But every time I have my #1 alternator off I get it bench tested and maybe the brushes replaced depending on hours just because its a real pita to R&R it on the plane.  

Edited April 7 by kortopates

[Falcon Man]

On the advice of my IA - if your aircraft is fortunate to have dual alternators - operate primarily on the number 2 belt driven one as it is much simpler to R&R than number 1. Since operating in this manner the only failure issue I have had with number 1 is the shock drive wearing out.

[Bolter]

56 minutes ago, Falcon Man said:

On the advice of my IA - if your aircraft is fortunate to have dual alternators - operate primarily on the number 2 belt driven one as it is much simpler to R&R than number 1. Since operating in this manner the only failure issue I have had with number 1 is the shock drive wearing out.

Are the 2 alternators equal size in the TIO-360 engines in the M20K's?

[Falcon Man]

They are both 70 amp and different manufacturers as far as I know. 

[Fix]

My direct driven alternator just came back from an 500h inspection and both brushes was worn 6mm left on them.

Also drive coupling was worn, so it was out of spec.

 

This on ~600h

[kortopates]

They are both 70 amp TCM Alternators with different part #’s simply because one is gear driven and the other belt driven.

Because the belt driven alternator is always turning faster, do to the way it’s set up, it naturally already takes 80%+ of the load. Which is good because it’s easier to access and maintain.

Because of the load difference the #1 should go a long time. I have just about 2000 hrs on my #1 alternator drive coupling and no issues ever so far. I change the brushes out when ever i have it off for almost any reason to avoid ever having to remove it for brush change - which i have never has to do. TCM recommends changing them out at 500 hrs but i personally think that’s excessive plus we really don’t see dual alternator failures.


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[Will.iam]

On 4/6/2025 at 6:14 PM, Ragsf15e said:

I haven’t dug into this with my mechanic yet because my engine only has 200 hours, but what are the maintenance requirements for the adapters on the starter and the alternator? I have the dual alternators, so one is belt driven, but I think the other one has an adapter into the engine. I would think there are maintenance requirements so those don’t come apart and cycle pieces through the engine? And the same with the starter?

I think the starter adapter and starter give indications before complete failure at least that was my experience. I had my plane for 6 months when i got the first starter adapter slip on starting. I was worried as i had mechanics tell me anything from replace it asap to wait until next annual. I chose the later and only had it slip 2 other times in the last 5 months to annual. 3 years later i started my plane flew it 30 mins to grandberry and when i went to start it again it would not start. This time it was the starter as i couldn’t hear the starter spin like i did with the worn starter adapter previously. A local mechanic took a rubber mallet and banged on the starter housing and that allowed me to start and fly home. As a precaution i took the upper cowl off and tapped the starter with a rubber mallet so that when i went to fly it next to my mechanic they could replace it which they are doing now as we speak. So even though both have stopped working reliably in the past they gave me enough warning to not be stuck AOG at an off station. Maybe i was lucky but i don’t lose sleep over when the new ones will start failing in the future.