Ok guys, when I mean broken alternator… I’m talking in the literal sense.


I own a Cessna 205 with an IO-550-F

First time it happened 500hours ago, when the 3 bolts just broke in half during flight.

2nd time the bolts just came loose.

Now its been 4 times that the alternator wants to open in half.
We’ve tried 2 different alternators (Hartzell & Kelly Aerospace)

Also, I don’t feel any weird vibration while flying


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Interested in what you come up with as I am running a 550 in a 206 . 4 times it’s come apart ? Obviously something very wrong there . Never really heard much about alternators blowing apart being a thing . Had my fair Share of belts break over the years but ,,,, exploding alternator , no .

I wonder if you need some sort of vibration dampener from where it's mounted.

Or maybe a new torque wrench ?

Something is going very wrong there. How can the bolts come loose if they are properly lock wired?
Just because you can feel a vibration doesn't mean there isn't one there. Have you ever tried to run a dynamic balance on it to see what it says? May be worth it.

A1Skinner wrote:Something is going very wrong there. How can the bolts come loose if they are properly lock wired?
Just because you can feel a vibration doesn't mean there isn't one there. Have you ever tried to run a dynamic balance on it to see what it says? May be worth it.

Maybe someone (not the OP) doesn't understand clockwise and counter-clockwise rotation

I take it bolts are broke this time? If not they look to short looking at top bolt. I have never had a alternator come apart on any equipment I have owned or run.

It’s actually really weird.
Because no other components are broken, also there is not a single loose screw in the rest of the engine area or fuselage.

The only thing we’ve noticed, is movement in the Alternator Pulley that moves the belt.
It moves back and forward over its axis.
Some say its normal, but some say the movement is too much.




What do you guys think?


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Have you verified pulley alignment? Misalignment can create side load which should manifest itself in worn/broken belt or worse. Can you go with gear driven alternator? Still using a vacuum pump?

skyward II wrote:Have you verified pulley alignment? Misalignment can create side load which should manifest itself in worn/broken belt or worse. Can you go with gear driven alternator? Still using a vacuum pump?

Is there any certified alternators that go on the vac pad? If so I'd be interested to replace mine with one as I prefer that over a belt driven one.

A1Skinner wrote:

skyward II wrote:Have you verified pulley alignment? Misalignment can create side load which should manifest itself in worn/broken belt or worse. Can you go with gear driven alternator? Still using a vacuum pump?

Is there any certified alternators that go on the vac pad? If so I'd be interested to replace mine with one as I prefer that over a belt driven one.

I don’t know what certified offerings there are for IO 550. Just proposing some questions/alternatives he may want to run by A&P.

I bought a “shelved for 36 years” 182P that had the engine partially torn down. Sourcing/matching parts for alternator and mount was an absolute nightmare and I kept thinking “there has got to be something better”.

What do you guys think?

I think that is a lot of back and forth slop. Mine doesn't move.

That pulley has too much end play, might be part of the problem.

I’ve worked on dozens of big continentals, never seen an alternator come apart like that, something wrong with your installation. To state the obvious.

I’d be suspicious of the mount being loose and/or the pulley alignment being not so.

There’s nothing wrong with the installation if it’s all done properly, no need to go reinventing the wheel with aftermarket alternatives, unless that’s your thing.

I agree that tue pulley has too much play. I'm not sure that in itself would cause the alternator to come apart, bit I would definitely want it chacked into to make sure the gears aren't rubbing somewhere they shouldn't be in the case.

Yeah, but……if this has happened four times, what are the odds of getting four different alternators with that much slop?

I have had alternators fail on big Continentals…..but that picture gives a whole new meaning to “failure”.

First question I’d ask: Where are you getting your alternators? Are they new or rebuilt?

MTV

mtv wrote:Yeah, but……if this has happened four times, what are the odds of getting four different alternators with that much slop?

I have had alternators fail on big Continentals…..but that picture gives a whole new meaning to “failure”.

First question I’d ask: Where are you getting your alternators? Are they new or rebuilt?

MTV

The slop is in the alternator drive, not the alternator...

pabloecanales wrote:....The only thing we’ve noticed, is movement in the Alternator Pulley that moves the belt.
It moves back and forward over its axis.
Some say its normal, but some say the movement is too much.....

"Alternator pulley that moves the belt" being the pulley on the starter adapter, eh?
I replaced my starter adapter a couple years ago and don't remember anything like that much end play on the pullie.
Not saying that's what caused your alternator to self destruct, but it doesn't seem right.
If anything, I'd think that might tend to make it throw the belt. But who knows.

First alternator was new and the second one was factory rebuilt.

The thing here is… we even used Loctite on the screws

And they just broke in half [emoji3061]

So its not actually the quality of the alternator, it’s something else


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Run it with the cowl off and the ground and have someone stand and watch the alternator belt. If the moving pulley us the culprit you should be able to see it then. Move the throttle settings around to try your best to mimic flight settings.

I agree with A1. There must be an alignment problem. It may be happening at different RPMS

MW