Thoughts on a replacement Master/Battery solenoid

J0nathan225 · July 6, 2018

It comes in 3's I've always been told. The spark plug issue has been resolved and I have spares now too, but when I went to fly today I got no power after flipping the master switch to on for start.

On preflight the switch worked as I checked the stall horn and lights, but on subsequent flips I could hear the solenoid drop/engage, but the connection wasn't being made (I confirmed with a voltmeter). I cleaned the area and then tried rapid fire with 3-4 up down toggles and got a good connection after that. I switched it on 3-4 more times before heading home and it worked each time there after.

I seem to have the original Cutler-Hammer 6041H34B, though it looks pretty "gunked" up.

MB65E · July 8, 2018

Eaton is the current MFG. They make good stuff. You can upgrade to the higher current relay.

tail of caution, the battery relay failures can look exactly like partial battery failures. If the relay is working it could be the battery itself. I would spend money on load testing the battery If questionable. If the battery test is good then it’s the relay.

-Matt

J0nathan225 · July 9, 2018

Battery load tested ok and was replaced in February. Relay is original it seems, I think I'm heading to ACspruce's GA location tomorrow to grab a new skytec relay.

Yetti · July 9, 2018

I have replaced lots of metal can solenoids after they failed on high load situations. I think there has already been one of the Skytec that has gone south. Might be a good temp solution till you can get a good replacement. Would guess with the silicone that one has been apart once or twice. They look like they made it easy to take apart and clean.

Edited July 9, 2018 by Yetti

Ross Taylor · June 2, 2020

Hi fellow MSers. I'm reviving this thread, instead of starting anew, because it seems the most relevant. The master solenoid (power relay) on our '66 E is a bit flaky...sometimes it takes a bit to actuate, even though the master switch wiring is good and the battery is recent (and always maintained on a charger). In the applicable parts manual, it shows a 800128 part number for that power relay. I'm not finding that, but I did see a cross-reference chart indicating that either an Eaton 6041H105 or a 6041H231 were the current replacements. But that wasn't on any official Mooney document and seemed pretty generic. Neither of those numbers match the OPs part number, above. So, what's the right one for me? Thanks in advance!

Ross

J0nathan225 · June 2, 2020

16 minutes ago, Ross Taylor said:

Hi fellow MSers. I'm reviving this thread, instead of starting anew, because it seems the most relevant. The master solenoid (power relay) on our '66 E is a bit flaky...sometimes it takes a bit to actuate, even though the master switch wiring is good and the battery is recent (and always maintained on a charger). In the applicable parts manual, it shows a 800128 part number for that power relay. I'm not finding that, but I did see a cross-reference chart indicating that either an Eaton 6041H105 or a 6041H231 were the current replacements. But that wasn't on any official Mooney document and seemed pretty generic. Neither of those numbers match the OPs part number, above. So, what's the right one for me? Thanks in advance!

Ross

IDK the answer, but I didn't end up replacing it and still have the part. I'll get the P/N when I go to the hanger tomorrow.

MB65E · June 2, 2020

The original one is no longer available. I upgraded to a new Eaton one with increased amperage. $$$! It later failed miserably, so installed the original one. You can take it apart and clean contacts. I would not buy a new one.

-Matt

Ross Taylor · June 2, 2020

Just now, MB65E said:

The original one is no longer available. I upgraded to a new Eaton one with increased amperage. $$$! It later failed miserably, so installed the original one. You can take it apart and clean contacts. I would not buy a new one.

-Matt

Good call on the disassembly...I just noticed that it's not riveted together.

Andy95W · June 2, 2020

This one is FAA-PMA for every Mooney model except the M20A or B.

https://www.aircraftspruce.com/catalog/eppages/sts-12a24a.php

http://www.lamartech.com/files/128975167.pdf

Ross Taylor · June 2, 2020

Thanks @Andy95W - if I need a replacement that certainly looks like a much more affordable option. Great info...thank you.

EDIT to update the item number: Again, thanks for the links. MS is the most helpful place!

In reading the Lamar docs, it looks like the one I need for the master solenoid is this one - the STS-M12 (there are different versions, but this part number is the one listed as the replacement in the PMA doc Andy linked to): https://www.aircraftspruce.com/catalog/eppages/skytec07-03565.php

**carusoam** · June 2, 2020

They must get pretty dirty in the inside...

Each time the switch is thrown, a tiny, powerful spark leaps across the gap, and knocks off a dust particle sized piece on the other side...

Open the old one up, just to get a look inside...

PP thoughts only...

Best regards,

-a-

**jetdriven** · June 4, 2020

On 6/1/2020 at 9:20 PM, Ross Taylor said:

Thanks @Andy95W - if I need a replacement that certainly looks like a much more affordable option. Great info...thank you.

EDIT to update the item number: Again, thanks for the links. MS is the most helpful place!

In reading the Lamar docs, it looks like the one I need for the master solenoid is this one - the STS-M12 (there are different versions, but this part number is the one listed as the replacement in the PMA doc Andy linked to): https://www.aircraftspruce.com/catalog/eppages/skytec07-03565.php

The Iink is the STS-A12 But I bought the M12 last year at annual Works good Last long time. Add the diode too

MB65E · June 6, 2020

I took my expensive Eaton relay apart today.

In the metal tin can there is a steel sleeve where the barrel retracts into the magnet portion itself. My guess is that the housing was miss-aligned and wearing between the housing and the barrel. The contacts were clean and I don’t think that was the issue.
I lubed the barrel and sleeve and put it all back together.
Who Knows,

-Matt

**carusoam** · June 6, 2020

There must be a select Saint in charge of weary mechanical devices that we can pray to... for support...

Best regards,

-a-

**0TreeLemur** · February 20, 2021

On 6/5/2020 at 9:38 PM, MB65E said:

I took my expensive Eaton relay apart today.

In the metal tin can there is a steel sleeve where the barrel retracts into the magnet portion itself. My guess is that the housing was miss-aligned and wearing between the housing and the barrel. The contacts were clean and I don’t think that was the issue.
I lubed the barrel and sleeve and put it all back together.
Who Knows,

-Matt

Hi Matt,

I'm having the same problem. Master relay solenoid is sticky. If I tap on it with a rubber mallet it activates. How did your lube & clean work out? Still working? If so, what did you use to lubricate it?

Thanks,

Fred

Edited February 20, 2021 by 0TreeLemur
asked question about lubricant.

**carusoam** · February 20, 2021

Chances are...

The solenoid isn’t serviceable...

Which is odd...

Because it creates its own dirt with every internal spark it generates during normal operations...

To clean it probably requires taking it apart and proper reassembly...

Its a magnetic switch with a coil... the coil probably didn’t wear out...

PP thoughts only... not a mechanic...

Best regards,

-a-

Jim Peace · February 20, 2021

I carry a brand new spare with me....1964c. I had my friend redo the jumper cable for my application so I dont have to think about it if I need to replace..should be a 10 minute job to swap out and an hour to remove and replace the cowling.....

MB65E · February 20, 2021

I still have the original back in the airplane. It’s been working great. A few years ago The reason installed the new one is that I thought it was loosing current. Turned out to just be a bad battery, and a diode that blew in the Alternator. New Alt, Battery and relay were installed. Turned out the relay was probably fine.
I never did re-install the one I took apart.
Getting out of the left seat with a PAx already strapped in just to run out and tap the relay was getting old.

-Matt

**carusoam** · February 20, 2021

Jim,

What’s the big empty space...?

Looks like you filled the map in...

There should be an MS award to go with that!

The been there award!

Best regards,

-a-

Jim Peace · February 20, 2021

12 hours ago, carusoam said:

Jim,

What’s the big empty space...?

Looks like you filled the map in...

There should be an MS award to go with that!

The been there award!

Best regards,

-a-

I dont see that on my end....is that on all my posts?

**carusoam** · February 20, 2021

3 hours ago, Jim Peace said:

I dont see that on my end....is that on all my posts?

It’s cleared up today...

-a-

**0TreeLemur** · February 21, 2021

Ordered Sky-Tec master solenoid. A certified airplane part for less than 0.1 AMU is a treasure, especially one as essential as this one.

**carusoam** · February 21, 2021

11 hours ago, Jim Peace said:

I dont see that on my end....is that on all my posts?

magically it returned...

Might be iPad viewer related...

-a-

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