Alternator Bracket Failure

[Stephen Skinner]

Can someone help?

Last weekend on my way home from Niagara Falls I lost charging. I turned off everything except the radio an transponder. I only lost 0.2 volts for a 45 min flight. 

It looks like the adjusting link broke and hit the alternator fan. The fan came apart and put the alternator way out on balance. The imbalanced alternator broke the alternator bracket. 

From the third picture, is there supposed to be that 1" spacer that looks like it offsets the alternator to align the pulleys.

What is the correct bracket for mounting the alternator? Is this correct?

The alternator is a ALY 8420 and has been repaired and tested. 

[Yetti]

What engine? What model mooney?

[neilpilot]

40 minutes ago, Yetti said:

What engine? What model mooney?

M20G, O-360 based on OP's MS info

[Yetti]

Lycoming Parts manual should have it.  My bracket on the IO360 was full length and did not need spacers best I recall.  I would go with a longer bracket to prevent what happened to yours.  Probably not in Canada but fabbing a bracket out of mild steel would work pretty well.

[carusoam]

Stephen, 

First, thanks for sharing the photos.

Second, did your a lot of vibration to accompany that?  Or did the belt stay in place and just slip?

Third, which alternator was mounted on your plane?  From the photo it doesn't look like the original generator that used to be on your plane?  (Your logs may have some interesting info regarding the install and existing brackets...)

Best regards,

-a-

Edited April 14, 2017 by carusoam

[N201MKTurbo]

You are lucky!

That happened on my F and a piece of the alternator fan made a hole in the oil cooler. I luckily decided to land right away and check it out. I had 3 QTs of oil left. It took me about 7 min to land.

My engine has a stack of washers instead of the spacer, but same thing. 

[Stephen Skinner]

Hi, it is a O-360-A1D. In the logbook so far I have only found the alternator date it was serviced in 1993 but it was rebuilt only a few years ago. When I had it repaired this week the tech said everything looked new.

I did not notice a vibration and the belt did not come off.

Is the IO-360 and O-360 the same for alternator and brackets? I would think that I could find a part # that is ment for an alternator.

Lots of Mooneys are O-360 with an altenator. How are they mounted?

[Stephen Skinner]

47 minutes ago, N201MKTurbo said:

You are lucky!

That happened on my F and a piece of the alternator fan made a hole in the oil cooler. I luckily decided to land right away and check it out. I had 3 QTs of oil left. It took me about 7 min to land.

My engine has a stack of washers instead of the spacer, but same thing. 

Wow, that was close. I see no other damage but it could have been much worse. How did you fix it?

[carusoam]

The O360 originally came with a 50Amp(?) AC/Delco generator and a mechanical voltage regulator mounted on the firewall.

Getting an alternator probably came with some small change to the bracketry to align the belt and pulleys.

There was an air hose that was used to cool the generator connected to the front of the cowling.  The alternator has its own fan, which looks like your may need to be replaced...

Often these devices have their basis in the automotive world.  Their parts can be found inexpensively.

The brackets are sometimes specific to the engine set-up.  Lots of O360s in the world...

Make sure you are getting the right parts installed the right way to avoid the same thing from happening.  

Broken parts can get stuck in the wrong place as indicated above...

PP thoughts, not a mechanic.

Best regards,

-a-

Edited April 14, 2017 by carusoam

[Stephen Skinner]

Yes, the fan is replaced, And it has air hose going to the back of the altenator.

Yes, I want to makes sure the right parts are going back in so this does not happen again.

I found a note in the Journey Log July 2012 of the altenator mounts tightened. There is lot of ware on the bracket and was loose again. So the correct parts are very important. This probably the cause of the link failure then everything else went after that.

 

[N201MKTurbo]

1 hour ago, Stephen Skinner said:

Wow, that was close. I see no other damage but it could have been much worse. How did you fix it?

I had most of the parts for an alternator which I took to the local accessories guy and he made an alternator out of my box of parts. He may have thrown in a few from his box of parts. I think he charged me $65. I had a spare oil cooler. the next weekend a friend flew me and my tool box and parts to the desolate airport (E24) in a 172. We replaced the alternator and oil cooler on the ramp.

Normally, leaving your stuff sitting in the middle of the res for a week would invite vandalism, but this is a part time air tanker base and it was fire season so the airport was manned 24/7 at the time. 

When It happened I called a friend of mine who just happened to be at the airport and he borrowed a Bonanza and came and picked me up.

[Yetti]

I think the bracket broke then it took out the adjustment arm.  Mine has one long bolt on the bracket that goes all the way through.  The nut is a castle nut and is cotter pinned. That allow the whole alternator to rotate.   The two bolts you have with the nylock nuts may have put not normal forces on the bracket causing it to fail.  STC instructions from the conversion might be the ticket to the proper way.

[N201MKTurbo]

9 minutes ago, Yetti said:

I think the bracket broke then it took out the adjustment arm.  Mine has one long bolt on the bracket that goes all the way through.  The nut is a castle nut and is cotter pinned. That allow the whole alternator to rotate.   The two bolts you have with the nylock nuts may have put not normal forces on the bracket causing it to fail.  STC instructions from the conversion might be the ticket to the proper way.

Good catch on the nuts. They should be castellated nuts with cotter pins. Both my F and J were rigged just like he shows. It was the only way to get the pulleys to line up. Between the two of them I have over 4000 hours rigged that way.

[Stephen Skinner]

I will be replacing with castellated nuts and cotter pins for sure.

Attached is a diagram for the setup but it doesn't show the alternator in relation to the bracket or the 1" spacer.

It does show 2 different lengths of bolts that would suggest spacers. 

Does anyony have a copy of the STD instructions / diagram or know the STD #?

I thank you all for your help.

 

 

[Guest]

Normally alternators on Mooneys did not have cooling fans, the cooling Scat duct would suggest conversion from a generator which would be a Mooney kit not an STC.  You might consider a Plane Power upgrade, by the time you buy the Lycoming mounting brackets and tension arm you'll have just about paid for a Plane Power kit.  Likely in stock at Spruce or Cox Aviation in Oshawa.

Clarence

[N201MKTurbo]

I have all of your broken parts laying on my shelfs at the hangar. If you can't find them let me know.