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  #21  
Old 08-17-2017, 06:39 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by Bill.Peyton View Post
This is scary. I have the same plane power alternator with 500 plus hours on it. I just had the cowl off a couple of days ago. I think I will take a better look tomorrow.
If I had one, I'd pull it, dismantle, and install Time-Serts or similar in those threads. Time-Serts work very well.

http://www.timesert.com/
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  #22  
Old 08-17-2017, 07:04 AM
BillL BillL is offline
 
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Quote:
Originally Posted by DanH View Post
If I had one, I'd pull it, dismantle, and install Time-Serts or similar in those threads. Time-Serts work very well.

http://www.timesert.com/
+1 Those are the best design of an insert I have ever seen!

Inserts, or at least put in a fastener with proper thread length engaged for aluminum. The one picture appeared to be about half enough threads engaged. ~ 2D is good for this situation.
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Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
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  #23  
Old 08-17-2017, 07:13 AM
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Bill.Peyton Bill.Peyton is offline
 
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I'll look today. Need to determine if there is enough meat to increase dia. Of hole. I noticed that the new alternators do not use fasteners and now use a solid casting. It would be nice to obtain the new casting and just replace the two piece config.
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  #24  
Old 08-17-2017, 02:19 PM
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Bill.Peyton Bill.Peyton is offline
 
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I spoke with Hartzell who claims that this is a rare issue, maybe just 2 or 3. I also confirmed that the newer version is the same as the older version.

I inspected my FS-14B alternator and did not see anything suspicious. The two casting are held together with 4 #10 screws, the heads are easily visible through the front casting without disassembly. All four of the screws appeared to be flush and appeared tight. The two castings were tight against each respective surface.

I chose not to remove it yet since I have a trip coming up. This unit has over 500 hours on it. If it were going to come apart, it probably would have. In my application, the field is not energized except to test it periodically, so there is no torque on the shaft or housing resulting from current draw.

I just wonder if a few of the units were assembled with the incorrect length screws?
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  #25  
Old 08-17-2017, 05:24 PM
BillL BillL is offline
 
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Quote:
Originally Posted by Bill.Peyton View Post
I just wonder if a few of the units were assembled with the incorrect length screws?
It could just be an assembly issue, then it would be under warranty, no matter the hours.

Torque is irrelevant to this housing. Anytime accessories are bolted in line with the axis (in particular) of an engine they are subject to resonant vibrations. Diesel engines with rear drives and multiple hydraulic pumps will resonate like the prongs of a tuning fork. Aircraft engines don't have the high energy of a diesel, but far more than a typical terrestrial gasoline engine. This alternator does not look particularly stiff in a wagging direction. Looks can be deceiving, though. Only results count.
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Lord Kelvin:
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and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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  #26  
Old 08-17-2017, 09:24 PM
Jackm Jackm is offline
 
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I decided to buy and install same model as I needed to keep flying at time. My concern is, it looked all normal 15 hrs earlier during condition inspection. I do run mine in flight as part of test to ensure I do have reliable back up if needed but out of 500 hours maybe only 25 hrs under load. Even the new one installed, the flange doesn't seem to have a precise fit but only way of telling is to disassemble. I feel another 10 hrs flying that way would have wore a hole in oil filter and turn into bad day. Also between ours and friends airplane ( new) we have gone through four of main alternators. Maybe we just hard on Plane power
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  #27  
Old 08-18-2017, 03:42 PM
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Bill.Peyton Bill.Peyton is offline
 
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Well I decided to disassemble mine and take a look. Like Jack, my unit probably had less than 1 hour of total run time with the field powered up.

The good news was no issue was found with the hardware attaching the front case halves. The brushes looked fine and had .38", well over the require .25" remaining called out in the ICA.

What I did find is that the rear protective shield was cracked all the way through in a couple of areas.

I also found that the rear support bearing has been spinning in the rear case to the point of wearing an approximate .020 delta between the OD of the bearing and the ID of the rear housing. The actual sealed bearing itself was fine, rotated smoothly, and wasn't leaking grease. I was surprised that the rotor had not yet contacted the stator assembly with that much play in the shaft/bearing.

After a long discussion with the Hartzell tech rep., he informed me that the front case was being redesigned into a single piece housing, similar to the B&C products, and the older style case was being assembled in a different manner with different fasteners. Also, found out that these units are not overhaulable nor do any parts exist for field repair other than replacement brushes.

Bottom line, this one is also toast, and failure was imminent. A new B&C is on the way!

Below are some photos of the disassembled unit.


[IMG]IMG_1226 by Bill Peyton, on Flickr[/IMG]

[IMG]IMG_1224 by Bill Peyton, on Flickr[/IMG]
[IMG]IMG_1229 by Bill Peyton, on Flickr[/IMG]
[IMG]IMG_1234 by Bill Peyton, on Flickr[/IMG]


[IMG]IMG_1240 by Bill Peyton, on Flickr[/IMG]
[IMG]IMG_1236 by Bill Peyton, on Flickr[/IMG]
[IMG]IMG_1241 by Bill Peyton, on Flickr[/IMG]

You can see the wear in the casting bearing seat where the bearing has been spinning, along with all the metal dust that has accumulated on the housing
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Last edited by Bill.Peyton : 08-18-2017 at 03:44 PM.
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  #28  
Old 08-18-2017, 08:34 PM
jakej jakej is offline
 
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"I spoke with Hartzell who claims that this is a rare issue, maybe just 2 or 3. I also confirmed that the newer version is the same as the older version."

That's interesting, maybe they just haven't heard about the 5 x PP 60amp units I am replacing (I have the serial numbers as I installed 4 of them) as a result of failures.
2 are due to the Volt Regulator (earlier models had them externally attached) falling off the back plates at 200-300 hours, the other 2 had max amp ouput (50-60) with 1 found with 4 diodes failed & mine has to be tested yet to determine the cause. As the fault happened outback Oz I flew back home on # 2 Alt (PP FS-14B) I am now really concerned about it too.

Denial by any manufacturer is something I can not tolerate especially when customers ask my opinion about a particular product, needless to say I have subsequently bought 5 x B&C units.

IMO we should be advising anyone we know of the reported proven problems with critical to flight/engine products.

Be careful out there.

Last edited by jakej : 08-18-2017 at 08:43 PM.
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