Intermittent electrical problem 182K

A

assetengineering

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Grand Junction, CO
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Grand Junction Pilot
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I have a 182K that has developed an intermittent electrical problem. During decent or low power flight the avionics stack will lose power for a few seconds and recycle. It never seems to happen at cruise power or during takeoff. Only during decent and before landing at low power. I have had 2 mechanics and one avionics company look at it. The avionics master has been replaced and grounds checked but it has not fixed the problem. any ideas?
 
Weak battery and failing alternator.
 
Do you still have a generator, or has it been converted to an alternator? Have you checked the condition of both sides of the battery terminal connectors?
 
Henning said:
Do you still have a generator, or has it been converted to an alternator? Have you checked the condition of both sides of the battery terminal connectors?
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I would look there first too.....
 
Do you have a voltmeter and if so what is it showing when this happens ??? Is the radio stack the only thing losing power or does everything go dark ??. Please describe what you are seeing as best you can, details of what is loosing power may help to locate the fault.
 
Vaflier said:
Do you have a voltmeter and if so what is it showing when this happens ??? Is the radio stack the only thing losing power or does everything go dark ??. Please describe what you are seeing as best you can, details of what is loosing power may help to locate the fault.
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If the plane has a cigarette lighter ,, you can plug in one of those inexpensive volt meters and monitor what happens during the "event"..
 
By 1967 all Cessnas had alternators.

Check grounds and battery connections.

Then take the alternator to an overhaul shop.

If you don't have a modern voltage regulator, get one. Probably a Zeftronics.


Edit: Oh, forgot....install a new belt as well.
 
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Throwing parts at the problem tends to be a very expensive way to fix things. Much better to diagnose the problem and fix the item which is causing it. I seriously doubt that all the parts mentioned are needed to fix this issue. An electrical diagram and more info would be the first place to start. Unless of course money is no object.
 
The buss voltage drops below 9 volts, the radios shut down, the voltage spikes above 9 volts (no load) and the radios turn back on.

Do you have a electronic voltage regulator?
 
Vaflier said:
Throwing parts at the problem tends to be a very expensive way to fix things. .
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Common misconception.

Sometimes. If you are flying around with 20 year old alternators and voltage regulators you are asking for trouble.

I have a history of leaving a lot "time on the bench." I also have a history of thousands of 135 flights without undo maintenance away from base. You can talk about money or you can talk about "real" money.
 
kgruber said:
Common misconception.

Sometimes. If you are flying around with 20 year old alternators and voltage regulators you are asking for trouble.

I have a history of leaving a lot "time on the bench." I also have a history of thousands of 135 flights without undo maintenance away from base. You can talk about money or you can talk about "real" money.
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I would not disagree with your line of thought, however it is entirely possible and in fact it may be likely that all of these new parts still will not solve the problem. I firmly believe in spending what I need to spend to take great care of my aircraft, but I really hate to spend money with no real gain. My point was that without more info a good diagnosis Is not really possible. I have a suspicion that it may be simply a bad master switch which would still be a problem if all this other work is performed. I am by no means sure of that but without more info I cannot be sure. Electrical gremlins can be the hardest things to fix especially if they are intermittent and usually the shortest path to a good fix is a logical diagnosis of the symptoms combined with proper analysis of the schematics. My approach is based on my personal experience and a desire to help a fellow aviator resolve his problem at minimal cost.
 
kgruber said:
Common misconception.

Sometimes. If you are flying around with 20 year old alternators and voltage regulators you are asking for trouble.

I have a history of leaving a lot "time on the bench." I also have a history of thousands of 135 flights without undo maintenance away from base. You can talk about money or you can talk about "real" money.
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That's the difference between a hobby and a business though. 135 it's not the cost of maintenance that's the big problem, it's the loss of revenue and customers when you can't fulfill your contracts.
 
No lie. We had only one customer who guaranteed us 40 hours a month in a KA200.

But still, I'd NEVER replace the alternator on a 182 without changing the voltage regulator, if it were all 1967 vintage. But then, that's me.
 
kgruber said:
But still, I'd NEVER replace the alternator on a 182 without changing the voltage regulator, if it were all 1967 vintage. But then, that's me.
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I wouldn't replace either one of them without instrumenting the system and testing it for a proper diagnosis, but that's just the engineer in me! I'm one of those guys that will spend 3 hours chasing a bad $5 part just for the challenge.
 
It's almost never the alternator. And auto zone can test it
I had an avionics bus do the same in my 150 it was a damn rouge screw stuck in the circuit breaker panel shorting it when it "jiggled" . I happened to see a spark when I kind of punched the bus bar in frustration and found the problem. :)
 
I haven't read any of this thread....but I have to say, $182,000 sounds expensive for a simple electrical problem!
 
Hey Guys,
Thanks for all the replies. I don't want to throw money at this but I don't want to have some kind of "incident" either. Better to spend some money and have new equipment at the end of the day. My problem continues but here is some more information:

1. I have a battery that is less than 1 year old and it tests good.
2. I replaced the alternator after testing it and it showed some weak fields. Did not solve the problem. Sounds like I should have replaced the voltage regulator while I was at it?
3. The problem seems to be getting worse and happens each flight now. It only happens at low rpm and almost always in the flare. It also happens most of the time when the plane "bumps down" on the runway. At this point I am not flying the airplane for fear of damaging the avionics.
4. The problem is not isolated to the avionics. Radios go out first and if the problem extends long enough other main bus items drop off (i.e. cabin lights, EGT gauge, etc). Usually the power comes back on after only a second or two of flickering.
5. I am now suspecting a ground problem as it seems like a "loose wire" kind of issue. We did find the diode at the battery contactor was burned up so I am starting there and working back towards the master switch. I will replace the battery contactor in the process as it appears to be original equipment.

Look forward to any other comments you have. If nothing else, I am learning a lot about the electrical systems in my airplane! :mad2:
 
Is that a Kelly or Hartzell alternator? (Hartzell took over the Kelly line.) Those guys put way too much grease in the rear bearing in the alternator, and it gets out and gets flung onto the slip rings and contaminates the field brushes, raising the field resistance. That reduces the max available field current and weakens everything, especially at low RPM. Measure the field resistance, with the field disconnected from the regulator. A 12V alternator should have 3 -5 ohms resistance in the field, and it should remain relatively steady as the alternator is turned.

Seen this way too many times in the last six or eight years, yet they're still overgreasing them.

Dan
 
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