1957 Cessna 180A - Alternator Conversion

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Nicholas G Chatham

Filing Flight Plan
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NChatham
anyone have an issue converting the generator to alternator and the pulleys don't align properly? the kit we installed which is STC'd for the 180A airplane has the pulley on the alternator further aft than the engine driven pulley. burning up/throwing belts constantly.... Help!
 
How far displaced is the centerline of the alternator belt pulley from the centerline of the engine belt pulley? It's an O-470-K, right?
 
Nicholas G Chatham said:
see attached pic
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Can't tell the offset from the pic plus the belt is twisted. But if it is more than a pulley thickness off then usually its wrongs mounts or the mounts are not installed in the proper locations. Need to verify the mount P/Ns and their proper locations per the drawings. If the offset is less than a pulley width look at the spacer installations. Is this a new installation?
 
It's hard to tell from the photo, but it looks like the offset is significant enough that something is missing, like maybe an adapter between the generator mounting bracket and the alternator mounts so that the centerline of both pulleys are aligned.

O-470-K Arrangement.jpg
 
I'm not the least bit familiar with those parts
so just spit ballin here....
if there's nothing missing
and you in fact have the correct parts
then something is put on backwards, upside down, out of order, or catywampus. I'm betting on upside down, out of order, or backwards.
 
I'm getting pushback from the mechanic, he's saying it's fine.... it's definitely more than a pulley of offset....
 
Bell206 said:
Can't tell the offset from the pic plus the belt is twisted. But if it is more than a pulley thickness off then usually its wrongs mounts or the mounts are not installed in the proper locations. Need to verify the mount P/Ns and their proper locations per the drawings. If the offset is less than a pulley width look at the spacer installations. Is this a new installation?
Click to expand...
yes new install....
 
Nicholas G Chatham said:
I'm getting pushback from the mechanic,
Click to expand...
Well I can't comment on this statement as your APIA is not here to post, but if you believe he is not be supportive then its time to find other APIA. Given its a new install and a Planepower kit I think you'll have your fix in the near future.
 
There are several different brackets for the generator, and one for the alternator. See the differences:

upload_2021-11-3_18-48-4.png

upload_2021-11-3_18-48-25.png


upload_2021-11-3_18-48-47.png

upload_2021-11-3_18-49-5.png

upload_2021-11-3_18-49-30.png

Then there is one more, the latest version, that has the mount cast as part of the left rear engine mount leg. Got no picture. Non-shockmount.

I have had the fun of fixing a few sketchy installations. Found, for instance, non-shockmounted alternators mounted on old shockmount brackets, with non-shockmount adjusting arms. The result is engine vibration tearing everything apart. Misaligned pulleys, too. Found one alternator belt rubbing on a fuel injection servo fitting, eating right through it. Imagine if it had cut through to the fuel channel inside? Fuel everywhere, under pressure. Flames.

You need someone able and willing to sort this out. Some of these STCs aren't as plug-and-play as owners think. When dealing with older models and a lot of obsolete mounts, you get into some difficulties.
 
Nicholas G Chatham said:
I'm getting pushback from the mechanic, he's saying it's fine.
Click to expand...

As I said, you need to fire your mechanic. That alternator installation is FAR from acceptable. The belt is twisted so much I can't tell from the picture if its the side of the belt that is around the drive pulley. And there are chunks missing from the belt as a result.
 
Timbeck2 said:
As I said, you need to fire your mechanic. That alternator installation is FAR from acceptable. The belt is twisted so much I can't tell from the picture if its the side of the belt that is around the drive pulley. And there are chunks missing from the belt as a result.
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Yes. We need a picture that doesn't have the obstructing object in front of the alternator. I want to see the whole alternator mounting setup.
 
Dan Thomas said:
Yes. We need a picture that doesn't have the obstructing object in front of the alternator. I want to see the whole alternator mounting setup.
Click to expand...
These are the best I have currently....
 

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Nicholas G Chatham said:
These are the best I have currently....
Click to expand...
Nees a shot from under the alternator, to see the bracket. I suspect it might be installed back-to-front. Even with the spacer the alternator is too far aft.
 
looking at those exploded diagrams in post #14
What I was getting at earlier....I was thinking a likely suspect is that those arms for example...items 12 and 13 in the first image could be on the wrong side of the yoke flanges. + the flange could be mounted upside down....something like that.
or maybe more likely if these area all options in one kit...that he mixed and matched parts from the different configurations.

It's been too many years ago since my experience as a Maintenance Reliability Engineer in a paper mill to remember much, but we used to take shaft alignment very seriously, using lasers and precision tools...before lasers were common. I don't recall our spec's now but belt alignment was held pretty tight..... misalignment is a very common cause of not only belt wear and failure, but other problems too...sheave failure and even bearing failure in the alternator, etc.. If a mechanic is pushing back when there is visible misalignment...then I'd be surprised if there's not more to the story.
 
Brad W said:
It's been too many years ago since my experience as a Maintenance Reliability Engineer in a paper mill to remember much, but we used to take shaft alignment very seriously, using lasers and precision tools...before lasers were common. I don't recall our spec's now but belt alignment was held pretty tight..... misalignment is a very common cause of not only belt wear and failure, but other problems too...sheave failure and even bearing failure in the alternator, etc.. If a mechanic is pushing back when there is visible misalignment...then I'd be surprised if there's not more to the story.
Click to expand...

I worked as an HVAC millwright in my 20s, and the acceptable alignment tolerances on large multiple v-belt drives were measured in thousandths. The drive arrangements on large built up air handlers the size of a small house typically had a 150 HP motor driving a 200,000 CFM fan using six v-belts.

As you said, any misalignment of the sheaves or failure to orient the fan and motor shafts exactly parallel to each other in all planes would result in expensive failures with unacceptable equipment downtime.

While the tolerances might not be as strict for the alternator installation, the same alignment standards are necessary. It's a safety of flight issue.

The OP's installation obviously has a serious misalignment, and as some have suggested, there must be incorrect brackets or similar issues. His mechanic's opinion that it's "fine" is troubling to say the least. I hope he can get it resolved.
 
Generators have that "bootstrapping" advantage, able to self-excite if the battery is dead, but that is the only advantage. Alternators displaced generators in cars nearly 60 years ago and the industry never looked back. I have maintained both generators and alternators and I know that I wouldn't want a generator. There are some alternator-equipped airplanes that have a small battery holder with a few D-cells in it and a switch on the panel to trigger the alternator's field if the battery was dead and the airplane hand-propped. One quick push does it.

All of a generator's output passes through large carbon brushes on the armature. Those brushes wear, as does the armature's commutator, and they also generate some radio noise. That setup is necessary to mechanically turn the armatures' AC output into DC, and it was designed long before modern solid-state electronic diodes were available. The alternator's output comes from its stator, and is rectified by diodes. The rotor is the field and its fed by small carbon brushes, and if the 500-hour internal inspections are done like they should be, that alternator can last many thousands of hours. The alternator puts out more current than the generator and weighs about half as much. It also generates large amounts of current at idle, something no generator can do. A long taxi at night with a generator can drain the battery. In generator-equipped airplanes I was used to seeing no output until the engine was at 1200 or 1300 RPM.

Parts for aircraft generators will one day disappear. No generators are being built AFAIK.
 
455 Bravo Uniform said:
He’s an idiot. Forget how it looks (which is wrong), but throwing a belt is the result. WTF?!
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Those older alternator-generator setups already had a habit of throwing the belt. Their shock-mounting would get the alternator vibrating violently enough in some vibration modes that the belt would come off. In some cases, re-clocking the prop would stop it. Continental abandoned the shockmount idea some time back, but one finds mix-and-match installations that really chew stuff up. Parts are expensive and take time to get, so some mechanics just cobble things together from the junk they have lying around instead of doing things right.
 
Dan Thomas said:
Generators have that "bootstrapping" advantage, able to self-excite if the battery is dead, but that is the only advantage. Alternators displaced generators in cars nearly 60 years ago and the industry never looked back.
Click to expand...

Generator brushes are far easier to change than alternator diodes, the failure of which is not that common but neither is it unknown.

The main reason alternators replaced generators was economics. An alternator is cheaper than a generator especially if the simplification of the regulator (no cut-out, no current regulator) is considered.

VW kept a generator in the air cooled Beetle until 1974. The engine cooling fan was driven from the back of the generator; the alternators did not have the right form factor to do this. At the time VW (prior to the Rabbit and Sirocco) was considered a decent quality vehicle so how bad could the generator have been?

I've four automobiles with generators, and still have an airplane with one. Never been motivated to switch to an alternator. It seems like the OP is going through a lot of hassle in exchange for modest performance and reliability gains.
 
flyingbrit said:
Generator brushes are far easier to change than alternator diodes, the failure of which is not that common but neither is it unknown.

The main reason alternators replaced generators was economics. An alternator is cheaper than a generator especially if the simplification of the regulator (no cut-out, no current regulator) is considered.
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Alternator brushes are also easy to change. I used to do them in less than an hour, start to finish, removal and installation of the alternator included. And they're way cheaper than generator brushes.

I never found alternator diodes failed. Ever. It's rare.

The alternator displaced the generator because it made plenty of power at idle, because it was cheaper, because it made more than double the power for its weight, and because it was easier to cool. It can be spun at much higher RPM than the generator, because it doesn't have all those lengthwise windings and the commutator segments in the armature to get thrown out at high speed. That lets it generate at idle, because it's geared to spin faster.

And I'm old enough to remember that red generator light starting to glow when I was idling, and the headlights dimming. Alternators eliminated that. A generator might be fine for the private owner that flies 100 hours a year, but for the flight school? Nope. Not one bit fine.

https://www.aopa.org/training-and-safety/students/solo/special/alternators-and-generators
 
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