The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!
I hadn't considered the dynamic-dynamics of the tire -vs- stable-constant mass distribution within a rotor. Good point.
I think that would be difficult to do and still be nice and civil. The question alone should be screaming at our community on which product they should not be purchasing.
A better question still is why vans has continued to sell them for so long. The uninformed builder would count that as an endorsement of suitability, reliability and (perhaps) value for money.
Humans seem to have an innate resistance to change. My guess is that vans always assumed this was a quality product and likely has not received much feedback that this assumption may be incorrect. If you share some of your frustration with replacing $1600 Alternators every 200 hours, I suspect they may respond with changes.
Happy to give them the benefit of the doubt. But I also find it hard to believe they are oblivious to the issue when there’s a new thread here every few weeks. Are you suggesting that none of these owners mentioned it to them? Seems a stretch but not impossible I suppose.
I guess I'll budget for a new B&C unit, then. Based on previous posts I've seen on VAF, I get the impression Hartzell isn't interested in supporting their products outside their warranty period. Which is too bad. I would have been willing to shell out a bit of coin to have them refurb my unit to incorporate the latest improvements. Oh well...
Freaking ridiculous. A basic FMEA should easily reveal the failure mode was not attributable to the removal of the back cover. The "new and improved" Hartzell is just grasping at straws looking for excuses to deny warranty claims.
I doubt anyone from vans spends much time here. When builders have issues, they call PP as well as post here. Why would someone call Vans when their alternator dies a year or two after completing their build. I could easilly be wrong on this, but my guess is that vans gets little feedback on this issue.
When you reassemble this unit are you going to use stainless gear clamps. If so place some insulation between the clamp and the aluminum housing to prevent corrosion. Stainless steel and aluminum don't party well together.
And here i thought you were an expermenter
I'll bet Hartzell's "basic FMEA" revealed that the failure was directly attributable to the owner's failure to properly torque the "back cover" screws.
Oh I am...but I think cutting the case in half made the unit beyond economic repair. It served its purpose.
As I figured out fairly recently, 'fabricator' and 'mechanic' are different skill sets and both rarely possessed by one person. I worked in a wind tunnel model shop for 20 years and could never understand why some excellent fabricators had no clue about screw spacing, appropriate screw diameter, and feel for torque; whereas some good mechanics were terrible at fabrication.
Looking at the case it looked like a couple of cheap hose clamps would hold it together, could be saved though for a demo unit for the class room.
I suspect this is part of the reason modern automotive engine bays are designed such that things that were considered relatively moderate maintenance now require dropping the entire engine from underneath the vehicle to be able to put a wrench on some of the screws.
I have typically seen 10,000 to 12,000 RPM ratings, but I suspect the manufacturer made that based on the bearing rating. When looking at bearing ratings, sideloads (radial loads) are important. The sideloads typically are from the belt tension. Over tension the belt, and the bearings can have higher rotational loads and overheat. All spell a shorter life for the bearing.
This just confirms that even when all of the known issues are absent, the auto self destruct feature of the PP still kicks in. Given their no repair stance, i am beginning to think this is a marketing driven thing. What a great way to drive revenue.Another member of our VAF community sent me his Plane Power AL12-EI60 to autopsy -- I don't think this one is much of a mystery; Clearly Colonel Mustard did it, in the library, with the candlestick
J'accuse le redresseur!
View attachment 90167
Whipping out the good old Fluke 87 Mark 5, I measured all the diodes and found that all but 2 had failed -- one of the stator windings and the center node of the stator windings -- so this alternator was down to 1 phase (out of 3) rectified DC, and a bunch of AC being put out onto the buss; ugly...
As to root cause -- not a clue. There's no scorching or burns anywhere on the cover, all of the stator and rotor windings measure the correct Ohms, the copper slip rings and brushes show almost no wear (not detectable with my calibrated Mark 1 eyeballs and fingernail). The rotor, pulley are secure, stable and no "wobble" is evident. The only indication of over temperature is the high side rectifier plate.
From a progressive failure signature, I suspect that the amount of "whine" heard in the headsets was pretty severe, and ultimately the OV-crowbar protection in the regulator kept tripping (this was confirmed by the owner.)
I mean, one does start to wonder.
Think of the additional business that would drive! $$$$
Except my reputation would take a major hit as soon as that "inspected" PP alt fails shortly after.
Aviation safety requires inspections…. Rather find a noisy bearing at annual than lose an alternator in flight. Just loosen the tensioner so you can turn and feel the pulley buy hand. Aerotech, B&C, PP I don’t care what alternator you have that’s an easy check.
How many hours on this one? How old was it?Another member of our VAF community sent me his Plane Power AL12-EI60 to autopsy -- I don't think this one is much of a mystery; Clearly Colonel Mustard did it, in the library, with the candlestick
J'accuse le redresseur!
View attachment 90167
Whipping out the good old Fluke 87 Mark 5, I measured all the diodes and found that all but 2 had failed -- one of the stator windings and the center node of the stator windings -- so this alternator was down to 1 phase (out of 3) rectified DC, and a bunch of AC being put out onto the buss; ugly...
As to root cause -- not a clue. There's no scorching or burns anywhere on the cover, all of the stator and rotor windings measure the correct Ohms, the copper slip rings and brushes show almost no wear (not detectable with my calibrated Mark 1 eyeballs and fingernail). The rotor, pulley are secure, stable and no "wobble" is evident. The only indication of over temperature is the high side rectifier plate.
From a progressive failure signature, I suspect that the amount of "whine" heard in the headsets was pretty severe, and ultimately the OV-crowbar protection in the regulator kept tripping (this was confirmed by the owner.)
So, why don’t you also pull all of the cylinders and check that the rod bolts are still tight each year? Some items are trustworthy and don’t need to be checked every year and some are not. How often do you pull off your accessory case and check the oil pump? Arguably the most safety critical component in your engine. Decisions have to be made. If I had a pp, i am sure i would check it at least every year, as they cannot be trusted. In reality , I would NEVER have one on my plane. My ND alternator has already given 1400 hours of service with no bearing issues, so why check it every year. When it finally dies, it will probably not be from failed bearings or the sre housing eating itself to death.
Because it takes 3 minutes. I don’t follow your oil pump and connecting rod checks…. Why even do a pre-flight with your logic?
You said “aviation safety requires checks.” Why is the alternator so important but not the other things i mentioned. My primary point was that all alternators do not need checks, just like oil pumps don’t need checks because their history is solid. That is not the case with pp, so THEY need checks, not necessarily all alternators.
Im gonna respectfully disagree. Inspection items that are easy to do at annual can catch a bad problem before it gets worse. We don’t “inspect” the oil pump…. But we do cut open filters, and use that information to determine if we need to inspect or IRAN an engine. And we do that filter check much more frequently than at annual because it is critical as you say.
That's what I did when my PP failed with only 226 hours. PP covered it under warranty with a new one but I opted to sell it and offset the cost of the B&C. When I spoke to a guy at PP (prior to Hartzell), he admitted the design of the internally regulated PP alternators were not the best.
Why would you need a STC for experimental certified aircraft? They are only for type certified. Maybe I am missing your point...
I don't believe it's the bearing itself that fails; (see post #1) the bearing starts to rotate in the case which then leads to a multitude of failures.
Hard to say without breaking it open -- the older serial number implies that it is a pre-Hartzell unit -- < 2014 or so.
You have to apply a side load while you’re turning to check for end play. Just rotating the shaft with no side load won’t catch bearing problems
This is mine. The ID plate states pretty clearly that it’s a Hartzell unit. Does this help?
