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InterAv Alternator took a dump!! 400 hrs.


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Main 60 amp C/B popped and only battery was left. Shut down everything electrical and then the Master switch. 

Reset the breaker and turned on the Master and it popped again. All done trouble shooting in flight (old airline practice to reset only one time)

Flew no electrical (like the old days) and landed.

With the C/B connected to the Main Buss and then going from there to the alternator power post obviously something along the power lead to the buss or the Alt itself had a short to ground. Pulled the power lead from the post on the alternator and turned on the Master again- NO C/B pop this time. 

Confirmed the short is in the alt. These alternators have an Isolation Diode (2) in series with the power lead so that the battery can not feed the alternator after shut down. Big time dead battery then.   My guess is that the Isolation diodes have shorted and battery power is going from the buss to the alternator as a dead short tripping the Main C/B.

Luckily these alternators have an Isolation Diode mounting plate attached to the back of the alternator so removing it tomorrow to check the diodes will be fairly easy. Time will tell.

Got lucky and found a complete InterAv system (as removed) with the same P/N for sale at a good price. Its on its way as a back up. 

Any Interav experts out there?  I have found all the manuals for InterAv and Motorola on line. These are older Motorola alternators. 

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If you do install that other Interav, inspect the drive pulley to confirm it is correct for you engine. Alternators with the same PN can come with either a standard or wide deck pully.

doubt you need it, but I have the Interav troubleshooting guide if you don't.

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Had my InterAV alternator fail on me a while back (just after getting the plane) and I found a replacement as well.  I seriously thought about the plane power replacement, but I really didn't want to rearrange my cowl when a direct replacement was so simple.  I had my original rebuilt by an auto electric man (these alternators were also used on tractors) and have it as a backup, as good as new.

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Thanks, I have the InterAv guide and the full Motorola rebuild manual..

Looked at the Planepower unit as I was searching but found the good deal on the InterAV system.

With my doghouse cooling changing to the Planepower would entail making all new seals for the front of the cowl so

less work and $$$$ right now. I've had good luck with the InterAV for almost 17 years. This is the first failure I've had. Its just happening at 400 hrs since new.

My biggest problem is that I'm so far out in the boonies, I have to ship everything out. Nothing local. 

 

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3 minutes ago, cliffy said:

My biggest problem is that I'm so far out in the boonies, I have to ship everything out. Nothing local.

At this point in history, I wonder what would be local for airplane parts.  I think we all have to ship them.  Just part of the deal.  But then, I'm in the boonies too.

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Actually it was an oblique shot at local "non-aviation" "non-certified" repair shop for alternators.

Can't get an 8130 from a local alternator shop. 

No offence meant to anyone, just a difference of opinion and one of my sticky points. 

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