How many people lost an Alternator/Voltage Regulator in flight?

[Bartman]

4 hours ago, N201MKTurbo said:

When I rebuilt my engine, I replaced the starter wire, the alternator wire and the field wires. And the P-leads.

If nothing else, it looks way nicer than those old ratty, greasy wires.

I had to borrow the hydraulic crimper from my electrician friend.

I didn’t do all of that, but we did replace the field wire and allowed for a loop of extra wire. In addition to regular inspection, every 5 years I install a new connector on the field wire. This is 2025 and even though it looked good, it got replaced this year on a fresh cut of wire. 

[Thedude]

On 12/3/2025 at 10:27 AM, PT20J said:

It seems from various posts here that the most common failure mode is a broken field wire. I have reinforced the wiring to the alternator to reduce vibration stress and I inspect it every time the cowling is off. 

Second most common problem seems to be voltage regulators. Mooney used different regulators over the years. I have a suspicion that the newer regulators may be more reliable, but I don’t know for sure. My 1994 MSE has a small Mooney brand. No idea who made it for Mooney, but it’s about the size of a Zeftronics. 

Can you share a photo of what you did to reinforce it?

[PT20J]

26 minutes ago, Thedude said:

Can you share a photo of what you did to reinforce it?

I don’t have a photo, but the 6 AWG output wire is well supported with clamps and I cable tied the other wires securely to that. I also eliminated the fuse holder connected to the AUX terminal for a tachometer option that was never installed on my airplane. 

[N201MKTurbo]

2 minutes ago, PT20J said:

I don’t have a photo, but the 6 AWG output wire is well supported with clamps and I cable tied the other wires securely to that. I also eliminated the fuse holder connected to the AUX terminal for a tachometer option that was never installed on my airplane. 

That’s what I’ve been doing. No trouble since tying the field wire to the output wire.

[Slick Nick]

44 minutes ago, PT20J said:

I don’t have a photo, but the 6 AWG output wire is well supported with clamps and I cable tied the other wires securely to that. I also eliminated the fuse holder connected to the AUX terminal for a tachometer option that was never installed on my airplane. 

I always wondered what the hell that fuse holder was for! Mechanical tach MSE here. 

[Yetti]

1 hour ago, PT20J said:

I don’t have a photo, but the 6 AWG output wire is well supported with clamps and I cable tied the other wires securely to that. I also eliminated the fuse holder connected to the AUX terminal for a tachometer option that was never installed on my airplane. 

Fun fact the Ford Lehman tractor engines that were used in lots of boats in the 1980s had a RPM take off from the alternator that looks really similar to the Alternators used in Mooney airplanes.

[McMooney]

lost the field wire once,  everything in birdy is now LED so probably the heaviest thing running , gns480 and a kx170b.

dropped the gear as soon as i noticed, landed about 45 mins later,  uneventful.  oh yeah, pulled out the handheld just in case.

if it were an option, i'd probably install an earthx battery as backup just to guarantee more electrons than fuel

Edited Friday at 04:48 PM by McMooney

[PT20J]

My panel draws about 6A @ 28V. My G3 LED landing and taxI lights (2 ea.) draw 6A if all are turned on. LED bulbs draw less current than incandescents, but they still can drain reserve from the battery and they would be the first load I’d shed. (Like many, I leave them on all the time to increase my visibility to other airplanes. I think it works because opposing traffic frequently reports me in sight before I see them).

[gabez]

I lost my alternator while flying with my daughter in my J35 and lost the voltage regulator on the ground in my mooney m20K. 

[Mooney in Oz]

On 12/4/2025 at 4:29 AM, LANCECASPER said:

If you end up doing your avionics upgrade you also might have another option - there's a small B&C alternator that can go where your vacuum pump is now. It provides 20 amp continuous and 30 amps max for essential things.

I had one fitted to my J and it is great. It helped a lot when my alternator belt let go. It automatically comes on line when a failure is detected.

[Mooney in Oz]

On 12/4/2025 at 5:18 AM, varlajo said:

I looked into that one, but it seems like it is designed specifically for Continental engines. Does anyone have experience matching it with IO-360? 

 

On 12/4/2025 at 9:00 AM, 201Mooniac said:

Presuming I can get it done, you are more than welcome to see it.  My IA is checking for clearances in the next couple of days and then I will attempt to get the DER to do the paperwork.  I'll let you know how it goes.

Mine was approved based on the STC PMA for the PA32, which has the Lycoming IO540 engine that we know has similarities to the IO360, despite 2 extra cylinders.

The standby alternator is the BC410. https://bandc.com/product/bc410-standby-alternator-system-for-piper-pa32-cherokee-six-lance-and-saratoga-stc-pma/#controller-regulator

Although there is a different approval process on my side of the world, I hope this helps and yours will be as seamless.

[N201MKTurbo]

1 hour ago, Mooney in Oz said:

 

Mine was approved based on the STC PMA for the PA32, which has the Lycoming IO540 engine that we know has similarities to the IO360, despite 2 extra cylinders.

The standby alternator is the BC410. https://bandc.com/product/bc410-standby-alternator-system-for-piper-pa32-cherokee-six-lance-and-saratoga-stc-pma/#controller-regulator

Although there is a different approval process on my side of the world, I hope this helps and yours will be as seamless.

Wow, your government man likes you….

My experience is if you treat the FAA folks like the overworked folks they are and don’t waste their precious time, they will go out of their way to get er done.

[Mooney in Oz]

10 hours ago, N201MKTurbo said:

Wow, your government man likes you….

Oh no they don’t. Some things are less onerous, but others are more so.

Not CASA, but designated engineers with CASA approval can sign these off and most are reasonable provided the submission has been properly completed. 

[Schllc]

You know, a car alternator runs 10x the average plane engine time and failures are pretty infrequent. They also cost about 300. 
I have never even heard of a voltage regulator in a car failing. Not saying it doesn’t but 45 years of cars and about 100 of them in that time…

one would think that 4000 for an alternator would make it a bit more robust than a 150 one from autozone…. 
I mean what efficacy do all of these onerous and obtuse rules provide?  
 

on average my alternator on cars fail around 200k miles (mostly Toyota). That equates to almost 6000 hours. 
 

they really need to rewrite the rules, they are not serving us well for safety….

[Andy95W]

25 minutes ago, Schllc said:

You know, a car alternator runs 10x the average plane engine time and failures are pretty infrequent. They also cost about 300. 
I have never even heard of a vintage regulator in a car failing. Not saying it doesn’t but 45 years of cars and about 100 of them in that time…

one would think that 4000 for an alternator would make it a bit more robust than a 150 one from autozone…. 
I mean what efficacy do all of these onerous and obtuse rules provide?  
 

on average my alternator on cars fail around 200k miles (mostly Toyota). That equates to almost 6000 hours. 
 

they really need to rewrite the rules, they are not serving us well for safety….

Hmm.  My M20C has the InterAv alternator conversion.  I just had it overhauled for about $800.

It was still working fine when I sent it in, I had assumed it was overhauled in 2005 when the previous owner overhauled the engine, but it wasn’t.  It turns out it was installed in 1995 and hadn’t been overhauled since.  It had about 5500 hours on it.  I did replace the voltage regulator with a PlanePower just because they are digital and far, far superior to the one that came with the original kit.

My advice to anyone with a generator that wants to change to an alternator- get a used InterAv, overhauled it, and install it with a PlanePower regulator.

[Schllc]

Alternator with adapter for an acclaim is north of 4k.  
to be fair, it didn’t fail, but was closing in on 20 years(900 hours) and it was replaced bc of extent of the work I’ve done, I didn’t want any down time when finished. 
but even so 4k?

[kortopates]

Alternator with adapter for an acclaim is north of 4k.  
to be fair, it didn’t fail, but was closing in on 20 years(900 hours) and it was replaced bc of extent of the work I’ve done, I didn’t want any down time when finished. 
but even so 4k?

But can be overhauled at a fraction of new $ including the adapter.
IMO, it makes zero sense to replace with new unless you’re on a trip and can’t wait for the down time in sending yours off.
I have done prophylactic inspections of my gear driven #1 alternator when it’s accessible, replacing worn parts, for the same reason you cited.

Regarding the car argument, i don’t know of anyone driving a car much older than 10 years old but most Mooney’s are many time that older. Years is just as important as hours due to corrosion and age.


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[Hank]

2 hours ago, kortopates said:

Regarding the car argument, i don’t know of anyone driving a car much older than 10 years old but most Mooney’s are many time that older. Years is just as important as hours due to corrosion and age.

My wife won't let me replace her 2011 Altima with > 230K miles, and my 2017 Altima is going strong at 173K. That's what 45-miles-each-way commutes does . . .

[Schllc]

3 hours ago, kortopates said:

But can be overhauled at a fraction of new $ including the adapter.
IMO, it makes zero sense to replace with new unless you’re on a trip and can’t wait for the down time in sending yours off.
I have done prophylactic inspections of my gear driven #1 alternator when it’s accessible, replacing worn parts, for the same reason you cited.

Regarding the car argument, i don’t know of anyone driving a car much older than 10 years old but most Mooney’s are many time that older. Years is just as important as hours due to corrosion and age.


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I drive my cars until they are done. Never did less than 250k in any, had three that went over 500k and one to 700k. All Toyotas, mostly work vehicles.  But my two land cruisers are at 300k and 200k, my old one that I gave to my daughter and mine which is a 2009 and about to hit 200k. 
I have never changed the alternator in either.

i agree that age makes a difference, but most planes are kept in hangars. 
and there is no real functional difference in an automobile alternator vs an airplane. 
in fact, didn’t someone bolt one on in a post here a while back. Apparently it had the exact same part number as the airplane version, but since he didn’t pay 10x the price it wasn’t legal. 
point was if it wasn’t so difficult to certify something for part 91, or it was possible to take a certified aircraft to experimental, we could see some actual innovation. 
imagine the efficiency and reliability of a Mooney with a 2025 computer controlled engine. It would be one tiny step from autonomous flight. 

[kortopates]

I drive my cars until they are done. Never did less than 250k in any, had three that went over 500k and one to 700k. All Toyotas, mostly work vehicles.  But my two land cruisers are at 300k and 200k, my old one that I gave to my daughter and mine which is a 2009 and about to hit 200k. 
I have never changed the alternator in either.
i agree that age makes a difference, but most planes are kept in hangars. 
and there is no real functional difference in an automobile alternator vs an airplane. 
in fact, didn’t someone bolt one on in a post here a while back. Apparently it had the exact same part number as the airplane version, but since he didn’t pay 10x the price it wasn’t legal. 
point was if it wasn’t so difficult to certify something for part 91, or it was possible to take a certified aircraft to experimental, we could see some actual innovation. 
imagine the efficiency and reliability of a Mooney with a 2025 computer controlled engine. It would be one tiny step from autonomous flight. 

Good for you but you and @Hank are not typical. For every long term car owner i can also point to folks that lease and get a new car every couple years.

You are right, most if not all aviation alternators came from the automotive world. But i believe they have supposedly heavier duty bearings/seals and brushes. Continental apparently uses Ford alternators. An aircraft is more hostile environment with all the vibration and i assume heavier loads on average.


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[Schllc]

31 minutes ago, kortopates said:

Good for you but you and @Hank are not typical. For every long term car owner i can also point to folks that lease and get a new car every couple years.

You are right, most if not all aviation alternators came from the automotive world. But i believe they have supposedly heavier duty bearings/seals and brushes. Continental apparently uses Ford alternators. An aircraft is more hostile environment with all the vibration and i assume heavier loads on average.


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I assume there is a standard that must be met to crossover which is a justifiable expense. But other than regulatory impediments, there is no other influence within its given market.  I’m sure some of the VC that has gone hard into aviation want payouts. 
but there is a cheaper way to do this for part 91.  
no rules doesn’t sound very wise, but there is no reason in this day and age and technology that things couldn’t be approved 1000x faster, easier and cheaper. 

[Will.iam]

I have a toyota with 120k but it was the first year hybrid camry in 2007 so going on 18 years the only thing i had to replace hybrid battery pack 2 years ago (16 years old) at the time we bought the car everyone screamed battery pack would be 10k to replace but by the time i needed one i got an aftermarket refurbished guaranteed for life of original owner for 2k.   Also have a toyota truck that is 2005 so so 20 years old with only 84k on it so it’s has sat more than it’s been run many a year. 
i think mooney cb creeps over to other things compared to regular people. 

[DC_Brasil]

On 12/3/2025 at 3:27 PM, PT20J said:

It seems from various posts here that the most common failure mode is a broken field wire.

Second most common problem seems to be voltage regulators. 

I've experienced both.

First it was a VR (I have the old electrodelta VR802). Luckily it failed on the ground. It was removed and repaired. The technician that worked on it said it was a bad resistor (or something like that) very easy and cheap to repair.

E few months ago I had the alternator go out right after takeoff returning home from an airport about 250nm away. After takeoff it went offline. I tried the checklist items without success. 

I was taking off an airport with absolutely no resources for a repair so I elected to continue flight on battery power to a larger field 20mins away. I informed ATC I could lose radio contact any minute and pushed on.

It was a national holiday, so I had to find an FBO to park, find and A&P to see the plane next morning and get on an airline flight back home :-(

It wasn't before a whole week I could go back to get the plane. It turned out to be broken field wire. We ended up redoing all connections to make them firmer.