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Diagnosing A Plane Power Bearing Failure

DanH

Legacy Member
Mentor
Symptom: Post-flight, engine still hot, moved the prop and heard a faint scraping noise. The noise was much diminished, almost non-existent when the engine was cold. Put another way, it wasn't notable if/when the prop was moved during a preflight.

Here's the interesting part. Removed cowl, removed the belt from the alternator pulley, spun the alternator by hand without any noise. Pushing and pulling the shaft axially made no difference. Otherwise wiggling the pulley detected no abnormality.

Hmmm.

Removed the alternator from the engine. Padded the jaws on my big shop vice with some soft aluminum, and clamped the pulley in the vice so the shaft pointed straight up, brush end on top. Now the problem was evident. With the pulley firmly fixed, the brush end of the alternator case could be moved roughly a millimeter total in any axis.

The problem was an enlarged bearing bore in the aluminum rear cover. The point here is that simply spinning the rotor isn't an inspection which will detect the problem. The bearing itself had not failed, so it rotated smoothly. The lever ratio (distance from the front bearing to the rear bearing/distance from the pulley centerline to the front bearing) is so large that hand-manipulating the pulley won't generate enough force to detect the problem. The weight of the rotor when horizontal also plays a role.

Scraping when hot, but not cold? I assume thermal expansion of the big Lycoming ring gear carrier, which would significantly tighten the belt in operation, apparently providing enough force to pull the rear end of the rotor into fleeting contact with the stator.

There is one other clue worth noting. This alternator had a bit more black dust in the vicinity of the rear cover. I assume it was brush dust. With the rear bearing floating around in an enlarged bearing bore, the brushes would have been subjected to more than normal movement in their holders.

Plane Power knows there is a problem. Their service rep cheerfully admits to it, but says the cause is too much belt tension. Some of us think that's unlikely, but I'm not going there with this thread. Nothing we say will fix the issue; that's up to Hartzell now. Until it is fixed, best if users learn how to safely live with it, i.e. catch during maintenance. And yes, we already ran a poll; B&C units appear to be far more reliable. In fairness, this tip would apply to any alternator, including B&C, and perhaps I'm just the last guy to have learned it the hard way.
 
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Years ago I went scrounging at a local car junk yard & gathered up 6 Nippon Denso style alternators off various makes of cars. Took them all apart to see what I could see. I would assume that they all had at least 100K miles on each of them. I was suprised to note that the front bearing was noisy on only one of them, brushes were nearly worn down to the holder on all of them, and 2/3 of them had the rear bearing knocked out of them. I would assume results would have been the same if I chose different manufacturers to look at.

Alternators ARE a maintenance item after all! No wonder there are so many rebuild/reman auto alternator sources out there! So how many 'miles' are on your alternators & do they need looking at for normal wear & tear?
 
... Until it is fixed, best if users learn how to safely live with it, i.e. catch during maintenance. ...
Thanks for flagging this, Dan. Were there any other indicators, like aluminum dust? Otherwise, short of removing the alternator, I guess move the prop a bit when the engine is hot and listen?
 
Were there any other indicators, like aluminum dust?

Not that I noticed externally. I did not personally dismantle this particular alternator, as it was subject to warranty, and most vendors buck when you hand 'em a component which looks like it has been opened. The service rep showed me the removed rear cover w/enlarged bearing bore the following day. The service center is local to me, so I was visiting in person.

Otherwise, short of removing the alternator, I guess move the prop a bit when the engine is hot and listen?

Yes, that's what tipped me to go looking. I think the longer term answer will be to add alternator removal to the annual condition inspection checklist. This particular problem was very evident with the alternator vertical and the pulley in a vice.
 
Good info. I'll add the listening to the alternator to my preflight inspection. Never know what else might be rubbing or clanking around...
 
Years ago I went scrounging at a local car junk yard & gathered up 6 Nippon Denso style alternators off various makes of cars. Took them all apart to see what I could see. I would assume that they all had at least 100K miles on each of them. I was suprised to note that the front bearing was noisy on only one of them, brushes were nearly worn down to the holder on all of them, and 2/3 of them had the rear bearing knocked out of them. I would assume results would have been the same if I chose different manufacturers to look at.

Alternators ARE a maintenance item after all! No wonder there are so many rebuild/reman auto alternator sources out there! So how many 'miles' are on your alternators & do they need looking at for normal wear & tear?

My 540/Bosch went 157k and was still quiet, M5/Bosch 155k still running, Volvo/Bosch still ran, rotated quiet at 140k, Sable/Motorcraft 100k had dry bearings, making noise and brushes nearly out. I am assuming the still running really would need overhaul.

Having a PP with less than 200 hrs (7500 mi at 37 MPH) and wallowed bearing housing does not compete with automotive.

The SRE/rear bearings are problematic. Good ball bearing design has to allow one race to float for differential expansion of housing and rotating element. Some designs use a needle bearing aft for this reason. Kind hard to assemble a pressed inner and outer race for both bearings.

At one time PP/Unipoint/XYZ had the issue addressed with a clever "expansion control ring". See photo for earlier PP bearing selection. Cheap and cheerful market?
IMG_4761.jpg
 
How many hours ??

Dan, nice catch !!!


How many hours on the alternator ??
That could give a clue to the inspection intervals.
 
Symptom: Post-flight, engine still hot, moved the prop and heard a faint scraping noise. The noise was much diminished, almost non-existent when the engine was cold. Put another way, it wasn't notable if/when the prop was moved during a preflight.

Here's the interesting part. Removed cowl, removed the belt from the alternator pulley, spun the alternator by hand without any noise. Pushing and pulling the shaft axially made no difference. Otherwise wiggling the pulley detected no abnormality.

Hmmm.

Removed the alternator from the engine. Padded the jaws on my big shop vice with some soft aluminum, and clamped the pulley in the vice so the shaft pointed straight up, brush end on top. Now the problem was evident. With the pulley firmly fixed, the brush end of the alternator case could be moved roughly a millimeter total in any axis.

The problem was an enlarged bearing bore in the aluminum rear cover. The point here is that simply spinning the rotor isn't an inspection which will detect the problem. The bearing itself had not failed, so it rotated smoothly. The lever ratio (distance from the front bearing to the rear bearing/distance from the pulley centerline to the front bearing) is so large that hand-manipulating the pulley won't generate enough force to detect the problem. The weight of the rotor when horizontal also plays a role.

Scraping when hot, but not cold? I assume thermal expansion of the big Lycoming ring gear carrier, which would significantly tighten the belt in operation, apparently providing enough force to pull the rear end of the rotor into fleeting contact with the stator.

There is one other clue worth noting. This alternator had a bit more black dust in the vicinity of the rear cover. I assume it was brush dust. With the rear bearing floating around in an enlarged bearing bore, the brushes would have been subjected to more than normal movement in their holders.

Plane Power knows there is a problem. Their service rep cheerfully admits to it, but says the cause is too much belt tension. Some of us think that's unlikely, but I'm not going there with this thread. Nothing we say will fix the issue; that's up to Hartzell now. Until it is fixed, best if users learn how to safely live with it, i.e. catch during maintenance. And yes, we already ran a poll; B&C units appear to be far more reliable. In fairness, this tip would apply to any alternator, including B&C, and perhaps I'm just the last guy to have learned it the hard way.

My first PP purchased in 2006 or 2007 (when they were pretty new to market) failed in this manner with about 350 hours on it. I took off for a flight and the field breaker tripped and wouldn't reset. I landed and it reset on the ground, so I tried again and it tripped off again very early in the takeoff roll. When I took the alternator off and disassembled it, I found evidence of the rotor rubbing the stator and it was clear that the rear bearing was very loose in the housing. The explanation that improper belt tension causes this is BS. This would impact the pulley end bearing more than the brush end. This is most likely caused by the bearing bore being machined too loose.

Skylor
 
My experiences mirror Bill's in automotive use. Seen multiple Denso, Bosch and Hitachi alternators go 5000-7500 hours with the bearings still fine. Brushes worn down to nubs in something like 4000 hours on the Denso and Bosch units in high revving applications, 7500 hours on the Hitachi brushes in one of my old cars before they finally hit the springs.

Never seen spun bearings in the housing on any auto alternators while I had my auto repair business or to date.

Not enough press fit would seem to be the cause, which is a lack of QC in the machining process or a wide OD variation on bearings (crappy bearing QC).

Doesn't seem to happen in the auto world any more in my experience with a lot of cars owned and worked on over 4 decades- mostly Japanese and German stuff.

Last time I replaced alternator bearings was back in the '80s on some ancient Delco Corvair units which had the small needle bearings at the rear.
 
Were you able to identify any process which enlarged the bearing bore in the housing? Did it become enlarged from some kind of deformation of the housing? Was it machined too big to start with? Given the high number of mass-produced alternator housings, that would seem to be a design/set-up problem at the manufacturer. As Bill points out, this bearing may be intended to have some end float? I would think a better design would be to have the bearing tight in the case, and let the steel shaft float in the inner race.

I wonder if the bearing is set in some kind of retention compound that failed? Loctite makes a liquid that is intended to set bearing races.

My PP alternator may provide a useful test case - I run with the belt looser than most would. 670 hrs and still OK - I think.
 
How many hours on the alternator ??
That could give a clue to the inspection intervals.

151 hours.

Regarding belt tension, it's 11~13 ft lbs with a new belt, and something like 7~9 with a used belt, per Lycoming.

All current automotive applications have gone to serpentine belts with spring-loaded idler tensioners. It guarantees near constant belt tension hot or cold, which may contribute to the very long bearing life of most auto alternators. Constant tension is definitely not the case with the Lycoming, as the big drive pulley expands a LOT when hot.

Still, if users are routinely over-tensioning belts, as Plane Power seems to think, the same problem would be showing up with B&C installations.
 
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Dan,

I have seen the same rear bearing race wear on a 70A Plane Power alternator. As in your case, the unit turned smoothly and had no externally obvious play.

If your unit has the 118mm OD stator, the replacement rear case listed here may fit it, but I haven't tried it myself:
https://www.maniacelectricmotors.com/75909204.html

It appears the 70A Plane Power is very similar to this alternator:
https://www.maniacelectricmotors.com/new-alternator-1994-1995-honda-civic.html
A fairly full list of repair parts is given there.

Hope that helps.
 
Just curious, is the service center open for anyone to visit/get help or are you on the bouncer's VIP list at the door? :rolleyes:

I imagine anyone can call the warranty line and tell them you wish to drop off your failed unit in person. That said (and I'm being PC here), I did not find my visit very useful, informationally speaking.
 
Dan,

I have seen the same rear bearing race wear on a 70A Plane Power alternator. As in your case, the unit turned smoothly and had no externally obvious play.

If your unit has the 118mm OD stator, the replacement rear case listed here may fit it, but I haven't tried it myself:
https://www.maniacelectricmotors.com/75909204.html

It appears the 70A Plane Power is very similar to this alternator:
https://www.maniacelectricmotors.com/new-alternator-1994-1995-honda-civic.html
A fairly full list of repair parts is given there.

Hope that helps.

FYI - The 60A unit has a 100 mm OD stator. Measured.
 
PP FS14-B Alternator

A slight thread drift however still about the Plane Power Alternators - just pulled my engine due Superior (not so) AD & found the alternator bearings are shot. Aircraft has 604 hrs. Why would this happen especially as it’s a vac pump pad mount unit & therefore minimal load on the bearings, unlike belt driven alternators?
This is the second unit that I know of, the other one had the bearing cone turning in the housing. My original belt driven PP unit failed at approx 200 hrs & I swore never to buy another of the PP units again, the failure of the # 2 PP unit just reaffirms my decision.
Ps -just a “heads up” The other PP Alt (gear driven- vac pad mount), not in my aircraft, had a lot of black dust around the housing - mine was clean & as I pulled the engine & had to remove the alt I checked it’s operation. I would not have known it was failing otherwise.
 
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Again, Dan has done a good service for PP alternator owners here on VAF on what to look out for. Hartzell knows about the issue but believes it's excessive belt tension? Bearing races spinning in the housing have nothing to do with belt tension as long as the bearing is still rolling.

Loose bearings may result in internal parts rubbing. Seized bearings will result in a smoked belt and no charging.

My suggestion to Hartzell is to use best quality bearings and other components and establish proper interference fits for those bearings in the housings. Step up the entire validation and QC process.

There are some people who have posted here on VAF with 1500-2000 hours on their OEM Denso alternators with original parts in place showing that belt tension probably isn't the issue. Hartzell should strive to achieve similar performance from their units. They are losing market share to competitors by not licking these issues after several years of bad press. I don't understand. The propeller division has a good reputation for their products and service. Can't this be applied to their alternators?

A couple hundred hours life here would generally be deemed unacceptable by most owners. I know a couple people with "old" PP units with a lot more hours than that on them. Did the product quality suffer after outsourcing offshore sometime back?
 
is Plane Power the same company that makes Sure Fly mags?

It is my understanding that this group of people did create the PP line and sold the company to a Hartzell division. 2016??

This certainly tarnishes the good name of Hartzell. It is hard to understand how/why the top management allows this to continue for years.
 
Posting to give a data point for reference.

I have a 60 amp PP purchased and installed around 2009. I have just over 700 hours with no issues. Perhaps in 2009 they were manufactured differently than the newer models. Of course Murphy’s Law may have it fail the next time I fly but it has been flawless so far. I am concerned considering the stories of all these failures. If I have to replace it, I might choose to replace it with a B&C.
 
Posting to give a data point for reference.

I have a 60 amp PP purchased and installed around 2009. I have just over 700 hours with no issues. Perhaps in 2009 they were manufactured differently than the newer models. Of course Murphy’s Law may have it fail the next time I fly but it has been flawless so far. I am concerned considering the stories of all these failures. If I have to replace it, I might choose to replace it with a B&C.

I does seem that pre 2011 or so units were pretty good, I know one guy with over 1700 hours on his. Not sure of the year parts production was switched offshore.
 
...found the alternator bearings are shot. Aircraft has 604 hrs. Why would this happen especially as it’s a vac pump pad mount unit & therefore minimal load on the bearings, unlike belt driven alternators?

Now that is a very interesting report.
 
Alternator

Here’s an idea- Hartzell should consider stop making alternators and ditch the whole process. Just sign a contract with B&C to provide all your alternators. I had a B&C on my RV-4 for 7 years without a hiccup and changed to a B&C on my -8 about 2 years ago. The -4 had an auto Nippon Denso on it when I got it so I decided to “upgrade” to a PP and had to send it back twice before the light bulb came on. In their defense PP did give me a full refund

I don’t know anyone with a B&C that’s had any issues. There may be some defective B&C alternators out there but you just don’t hear much gripe about them.
 
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Now that is a very interesting report.

I don't find that so interesting since it's fairly certain that high side loading isn't the cause of the other bearing failures either and certainly not the cause of outer bearing races spinning in the housings. If anything, the directly driven alternator eating bearings is simply confirmation of all this.

Crappy bearings with crappy grease or not enough of it is much more likely in my view.
 
Dan made an interesting comment:

"Constant tension is definitely not the case with the Lycoming, as the big drive pulley expands a LOT when hot."

If you're comparing auto applications to aviation, that factor in itself seems to be the biggest difference. High pulley ratios and an expanding drive pulley with no constant tension system look like a recipe for failed bearings.

Lycoming may recommend a belt tension, but their concern may really be belt operation (adequate drive force) more than life span of the alternator.

Has anyone tried running a belt "much looser"? Might slip when cold but my guess is that it will tension up when the drive pulley heats up. You surely can't hear a slipping/squealing belt on a Lycoming maybe, and excess slipping might fail your belt, but belts are easy to inspect and a lot cheaper.

... just a new guy and his two cents ...
 
...
Has anyone tried running a belt "much looser"? Might slip when cold but my guess is that it will tension up when the drive pulley heats up. You surely can't hear a slipping/squealing belt on a Lycoming maybe, and excess slipping might fail your belt, but belts are easy to inspect and a lot cheaper.

... just a new guy and his two cents ...
Good idea - I used a larger pulley which does two things I think are good:

1) more contact area for the belt - this should reduce the "tightness" requirement of the belt to get the same friction on the belt
2) slower turning alternator - still provides plenty of power for my requirements

http://www.rv8.ch/alternator-pulley-change/

The negatives are that it might require a cowl bump for spacing, depending on your installation. It did for me, but I needed one anyway for my FM-200.
 
In flight, I think you'll find that the flywheel doesn't get very hot in standard setups. With any kind of spinner gap, the high pressure airflow there flows right over it. The amount of air would be determined by any leaks around the baffling downstream. With low leakage, lower airflow and lower cooling. With felt seals here as some use (I think Dan does), would be far less net cooling of the flywheel area.

Drive ratios on auto alternators are frequently 2.5- 3 to 1. Highway cruise rpm on my manual transmission cars 3000-3500 rpm so alternator rotor speed there is 7500 to 10,500. At redline, over 20,000 rpm, though the engine doesn't spend much time there unless you're tracking it- which I have done a lot of and still no bearing failures in decades, even without spring tensioning setups.
 
Has anyone tried running a belt "much looser"?

Inadvertently I have, as a result of new belt stretch. The belt wasn’t what you’d describe as sloppy and I couldn’t hear it slipping, but the alternator output started coming and going and investigation revealed the groove in the pulley was polished. After correcting the belt tension that 24yo PP alternator soldiers on - fingers crossed. Don’t make ‘em like they used to, it would seam.
 
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Has anyone tried running a belt "much looser"? Might slip when cold but my guess is that it will tension up when the drive pulley heats up. .

I wouldn't say "much" looser, but I do have my belt set a bit looser than most, and enough looser that some hangar visitors have commented on it. Using the torque wrench slippage test, the alternator pulley slips below the specified range, but just barely.

My lower cowl plenum runs at about 85C per recent measurements on a day when OAT was 32C. The conduction path from the 150C cylinders into the crankcase, into the crankshaft, then out to the ring gear holder is long and most of the cross section of the ring gear holder is fairly thin. So I would guess the ring gear holder runs at less than 100C. Assuming it was installed at 20C, the thermal growth would be 0.002" per inch. (oops, switching unit systems here!) I don't know the pulley diameter, but it is surely less than 10" so the pulley circumference increases by less than 0.065".
 
Old PP

Posting to give a data point for reference.

I have a 60 amp PP purchased and installed around 2009. I have just over 700 hours with no issues. Perhaps in 2009 they were manufactured differently than the newer models. Of course Murphy’s Law may have it fail the next time I fly but it has been flawless so far. I am concerned considering the stories of all these failures. If I have to replace it, I might choose to replace it with a B&C.

I too have a 60 AMP Plane Power purchased in the 2009-2010 time frame (before Hartzell). In operation since 2014 and now closing in on 800 hours with no problems whatsoever (even original belt). No blast tube either.

I am planning to take it at least partially apart for brush inspection during my annual next month. Had even considered further disassembly just to get a really clear picture of condition. However, the old saw "If it ain't broke, don't fix it" does come to mind . . . . .
 
Odd Failure Mode

I have 20+ years of electric motor design experience. This is not a failure mode that would typically happen on a belt loaded bearing system. The belt provides good radial loading in a single direction. This failure mode is very common on fan/pump type loads. On that type of a load the opposite drive end bearing can be allowed to roll around the housing unless there is something in place to prevent rotation. I never like to see a bearing race in an aluminum housing unless it is mechanically held from rotating. If you care for a few rules of thumb keep reading. Press fit the OD or the ID, never both - it eliminates the internal bearing clearances. Always provide some axial pre-load, it keeps the balls rolling instead of sliding. If you ever hear a motor that sounds like there is sand in the bearings, it very likely doesn’t have any axial pre-load. If the bearing will see light radial loading you need to lock the outer race to prevent rotation (avoid press fit OD and ID per above). One of the four races (inner or outer) needs to be allowed to float axially to compensate for thermal expansion. Right at the top of what is needed for a quite, long lasting motor is good bearing fits, with extraordinary quality control. Motor bearings today are designed for 40k hour life, with 80k possible, and 120k desired. This is a topic careers are made of, hard to hash out via a couple of lines of text. I have not even touched on grease, cleanliness, and thermal conditions…. Not sure if any of this is useful to the conversation, thanks for reading - Jason
 
Denso has figured all this out years ago in the automotive world with obviously good design and materials. They are one of the if not the largest suppliers of alternators in the world for good reason. Their products last a very long time in my experience.

Bearing failures at less than 200 hours points to something being done very wrong at PP. Denso can design or select a bearing that will have proper ball to race clearance when pressed into the housing and onto the shaft. This is exactly what is needed to make it as reliable as they are.
 
Here is a photo of the replacement 70A housing I mentioned above.

It's interesting that it has a separate steel part that holds the rear bearing rather than using a simple recess machined into the aluminum. Perhaps they're on to something...
 

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I have 20+ years of electric motor design experience. This is not a failure mode that would typically happen on a belt loaded bearing system. The belt provides good radial loading in a single direction. This failure mode is very common on fan/pump type loads. On that type of a load the opposite drive end bearing can be allowed to roll around the housing unless there is something in place to prevent rotation. I never like to see a bearing race in an aluminum housing unless it is mechanically held from rotating. If you care for a few rules of thumb keep reading. Press fit the OD or the ID, never both - it eliminates the internal bearing clearances. Always provide some axial pre-load, it keeps the balls rolling instead of sliding. If you ever hear a motor that sounds like there is sand in the bearings, it very likely doesn’t have any axial pre-load. If the bearing will see light radial loading you need to lock the outer race to prevent rotation (avoid press fit OD and ID per above). One of the four races (inner or outer) needs to be allowed to float axially to compensate for thermal expansion. Right at the top of what is needed for a quite, long lasting motor is good bearing fits, with extraordinary quality control. Motor bearings today are designed for 40k hour life, with 80k possible, and 120k desired. This is a topic careers are made of, hard to hash out via a couple of lines of text. I have not even touched on grease, cleanliness, and thermal conditions…. Not sure if any of this is useful to the conversation, thanks for reading - Jason

Very useful, and thank you for contributing.

Experience question please. In this case the OD of the brush end bearing and the ID of the aluminum case appear to be dimensioned the same (32mm). Elevated temperature thus results in a clearance. The outer race is assumed to rotate, and the clearance grows. Is there a quick 'n dirty fix you think might work?
 
What is the design function, precisely?

Here is a photo of the replacement 70A housing I mentioned above.

It's interesting that it has a separate steel part that holds the rear bearing rather than using a simple recess machined into the aluminum. Perhaps they're on to something...

How does this work? Does it press onto the outer race then get assembled? It appears to have an internal screw? Is the SRE inner race pressed onto the rotor?
 
By using a steel bearing capture, they can keep the thermal expansion rate the same as the steel bearing. Could get away with a lighter press fit than in an aluminum housing.
 
How does this work? Does it press onto the outer race then get assembled? It appears to have an internal screw? Is the SRE inner race pressed onto the rotor?

Bill,

The steel part is permanently attached to the aluminum SRE frame, and I don't think the screw is intended to be removed.

I haven't tried installing this housing, but the rear bearing appears to be a press fit on the rotor shaft. I think the steel part is intended to press/slide? over the bearing OD when the housing is installed.
 
I have 20+ years of electric motor design experience. This is not a failure mode that would typically happen on a belt loaded bearing system. The belt provides good radial loading in a single direction. This failure mode is very common on fan/pump type loads. On that type of a load the opposite drive end bearing can be allowed to roll around the housing unless there is something in place to prevent rotation. I never like to see a bearing race in an aluminum housing unless it is mechanically held from rotating. If you care for a few rules of thumb keep reading. Press fit the OD or the ID, never both - it eliminates the internal bearing clearances. Always provide some axial pre-load, it keeps the balls rolling instead of sliding. If you ever hear a motor that sounds like there is sand in the bearings, it very likely doesn’t have any axial pre-load. If the bearing will see light radial loading you need to lock the outer race to prevent rotation (avoid press fit OD and ID per above). One of the four races (inner or outer) needs to be allowed to float axially to compensate for thermal expansion. Right at the top of what is needed for a quite, long lasting motor is good bearing fits, with extraordinary quality control. Motor bearings today are designed for 40k hour life, with 80k possible, and 120k desired. This is a topic careers are made of, hard to hash out via a couple of lines of text. I have not even touched on grease, cleanliness, and thermal conditions…. Not sure if any of this is useful to the conversation, thanks for reading - Jason

Thanks for this! Always learning. Imparo Ancora.
 
Check this - then

Very useful, and thank you for contributing.

Experience question please. In this case the OD of the brush end bearing and the ID of the aluminum case appear to be dimensioned the same (32mm). Elevated temperature thus results in a clearance. The outer race is assumed to rotate, and the clearance grows. Is there a quick 'n dirty fix you think might work?

Since this failure mode is not typical for this loading I would first try to find out what the cause is. So, to me step one would be to sweep the speed range of the alternator to look for a resonance, off hand I think this is a potential cause. The bandage to apply is something called a tolerance ring. You would of course need to open up the housing to make room, but they work. I experimented extensively with them, but they only made production a few times due to cost. Be careful when installing the bearing because you can not press on the balls, said another way you may not transfer any pressing loads from the inner race to the outer race via the balls. Much like men, these are very fragile components and while they may appear ok at first you HAVE damaged them and shortened the life of the bearing by pressing on them. - Jason
 
You could also use a bolted bearing capture for the outer race as some alternators use and thread the center shaft to capture the inner race with a small bolt and washer. I used this method on my belt idler. Nothing has spun on the aluminum shaft or housing. I did replace a crappy offshore bearing at around 50 hours with a German one which has gone around 400 more with no issues now.
 

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Just had my PP 60A alternator seize on my RV8. 171 hours. I do the required inspection at annual and loosen the belt to check for bearing noise. I just shipped it to PP overnight and they said they would see what happened and replace it.

I had flow the plane on 3 trips the last 3 weeks and was working on a fuel flow indicator problem. I had flown a test flight of about 20 min. and noticed a slight burning smell on shut down. I pulled the cowl and did a run up the next day of about 2 minutes. Loud squealing and smoke from the alternator pulley. We shot a temp probe on the alternator it was not that hot 94 F. the pulley was 167 F. If I was flying I am sure the belt would have failed quickly.

It was just luck that made me catch it before the next flight.

I will report on what PP comes up with.
 
Update.
Plane Power said my alternator seize was NOT a Bearing , but a stater issue. Something about heating up and binding during cool down. This actually makes sense since I had not problems in flight and only started to burn the belt during the ground run up with the cowl off the second day.

They treated me fine ans I now have a new one.
 
Maybe dumb idea....

I think I have the same rear bearing "failure." The pulley spins smooth with no noise. Had the radio on in the hangar and almost missed it. Moved one side of the pulley fore and the other aft and got a nice, low, clunk out of it. Had to do it multiple times, but, yup, sounds just like what Dan has. (Had the issue before seeing his post.)

Has anybody thought of a ND Suzuki alternator (from your local big box auto parts store) and swap out the back end with the Hartzell 11-1043 regulator brush assembly as a low cost alternative? Or is this silliness?
 
Chris,

Can you measure the OD of the stator (dark steel) as shown in the attached image? It would help narrow down the parts that might fit...

I'm guessing the OD will be 100mm or 110mm (with a slight chance for 102mm).
 

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Chris,

Can you measure the OD of the stator (dark steel) as shown in the attached image? It would help narrow down the parts that might fit...

I'm guessing the OD will be 100mm or 110mm (with a slight chance for 102mm).

We shall wait for conformation, but it should be 100mm for the 60 A.
 
I think I have the same rear bearing "failure." The pulley spins smooth with no noise. Had the radio on in the hangar and almost missed it. Moved one side of the pulley fore and the other aft and got a nice, low, clunk out of it. Had to do it multiple times, but, yup, sounds just like what Dan has. (Had the issue before seeing his post.)

Has anybody thought of a ND Suzuki alternator (from your local big box auto parts store) and swap out the back end with the Hartzell 11-1043 regulator brush assembly as a low cost alternative? Or is this silliness?

I have confirmed an OTS regulator will fit right in. You would have to ensure the wiring to the connector is correct. I have one unused if you are interested.

I bought a bunch of parts as part of an investigation that did not get used except to fit dimensionally. EI60A only.

Do let us know what you find. The unit has the pulley end bearing clamped in the housing. The PP EI60 I inspected/repaired had one of the retainer screws not seated from the factory.
 
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I had to re-read what I posted. It was a bit ambiguous.... I was just thinking about putting the Hartzell regulator/brushes into an existing auto/Samurai alternator to get whatever goodies the Hartzell set has in it, not necessarily swapping out the case itself. Although, that's not a bad idea, but won't be my first thing to try.

I've been extremely sidetracked with other things, so it could be a while before I to try anything. But, I'll post what I do. And the results, even if disappointing.

If I had a dollar for everything I thought was a good idea, tried, and scrapped after getting elbow deep into it......
 
Fantastic Idea !!!

I had to re-read what I posted. It was a bit ambiguous.... I was just thinking about putting the Hartzell regulator/brushes into an existing auto/Samurai alternator to get whatever goodies the Hartzell set has in it, not necessarily swapping out the case itself. Although, that's not a bad idea, but won't be my first thing to try.

I've been extremely sidetracked with other things, so it could be a while before I to try anything. But, I'll post what I do. And the results, even if disappointing.

If I had a dollar for everything I thought was a good idea, tried, and scrapped after getting elbow deep into it......

Actually this is a great idea! The most significant difference is the regulator and modified brush holder! I gave myself a dope slap for not thinking of this simple thing - the regulator is available. but nothing else. The nothing else are all the failures!!

Now we just need to identify some good specific alternators and sources that are ND remanufactured and test the idea!!. Do let me know what you find. I will do the same.

We likely will get a mounting that looks like the B&C as the PP60A has no mount lug on the SRE housing. I can not find an automotive equal for that SRE housing and I am not sure that we need to. The weight does increase, or it can be cut off - against the prime intent of the direction.
 
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