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  #21  
Old 06-25-2021, 06:02 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by RVbySDI View Post
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.
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  #22  
Old 06-25-2021, 07:05 AM
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DanH DanH is online now
 
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Quote:
Originally Posted by jakej View Post
...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.
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  #23  
Old 06-25-2021, 07:05 AM
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olyolson olyolson is offline
 
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Location: St Louis, MO
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Default 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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Last edited by olyolson : 06-25-2021 at 07:16 AM.
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  #24  
Old 06-25-2021, 07:40 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by DanH View Post
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.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ


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  #25  
Old 06-25-2021, 08:12 AM
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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 ...
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  #26  
Old 06-25-2021, 08:34 AM
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rv8ch rv8ch is offline
 
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Quote:
Originally Posted by wcalvert View Post
...
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.
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  #27  
Old 06-25-2021, 08:54 AM
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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.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ


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  #28  
Old 06-25-2021, 10:41 AM
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Malndi Malndi is offline
 
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Quote:
Originally Posted by wcalvert View Post

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.

Last edited by Malndi : 06-25-2021 at 10:51 AM.
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  #29  
Old 06-25-2021, 10:57 AM
scsmith scsmith is offline
 
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Quote:
Originally Posted by wcalvert View Post
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".
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  #30  
Old 06-25-2021, 12:34 PM
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Dan Langhout Dan Langhout is offline
 
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Default Old PP

Quote:
Originally Posted by RVbySDI View Post
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 . . . . .
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