[avi8tor50]

Hi all-
Was flying back from the TERRIFIC weekend put on by Larry Vetterman in Hot Springs SD when I noticed that my alternator out warning light started flickering. It would never come on and stay on except a few times for a split second. Mostly flickering. I watched the voltage indicator when the flickering occured and there was no change but when the light actually came on for a second the voltage would drop from the usual 14.3 v to maybe 14.2, 14.1, 14.0 but never below that. There were periods with no light flickering and I watched the voltage indicator for the entire trip and it never realled dropped for any period of time from the usual 14.3v.

I know alternator/electrical issues can be complex but what I am looking for is some guidance in how to approach this problem. I have the Plane Power 60Amp alternator AL 12-E160/B model which has an internal regulator.

I plan to remove the cowl and do the usual external inspection and will also crawl under the panel and check the wire from the warning lamp light however since I have seen a slight voltage drop that coincides with those times when the lamp stays on for a split second I suspect that this is NOT a warning light issue.

If the electrical gurus in the audience or anyone else for that matter would care to provide a bit of insight it would be much appreciated!

Thanks all.

Peter K
9A-230 hrs

 

[Ron Lee]

I can't help with more esoteric causal factors. I would start by checking all the connections. Also see if Plane Power has a troubleshooting guide.

 

[turbo]

i would check the power coming into the bus for tightness. mine was a 1/3 loose and solved my low voltage problem a few years ago. good luck.

 

[Joe]

Alternator Troubleshooting

Peter,

I troubleshot a friend's RV-7A with a similar problem a few years ago and it turned out to be a bad crimp on the B-lead connection right at the alternator. Good output on the stud and nothing on the wire on the terminal. This was on the wiring harness supplied by Van's.

Disregarding bad connections, the problem is most likely caused by the brushes wearing. If you remove the alternator, you can remove them and take them to an automotive electric repair shop for a replacement set. Or just take in the alternator and have it bench tested. (I tested my own by mounting it in a vice and spinning it with an electric drill while looking for output).

 

[fl-mike]

I had the exact same problem last month with my PlanePower alternator. Seemed to be charging okay and producing current, but I was getting a flickering fault light. Ended up sending it back. They gave me a new one even though mine was out of warranty. Said it had a spun bearing and was from a batch that they had problems with. I spent more time troubleshooting it than it took them to swap mine and get it back to me!

BTW, I did check all connections first. I also had a whine in the transmitted audio that was new and RPM related.

 

[hudgin]

Had the exact same problem coming home from Oshkosh and have been having the same problem over again for three times in less than 200 hours. I live close to Plane Power so it is easy to take it and wait for the repair. Each time it has been a broken connection to the stator. The wire bumps up next to ground and causes a voltage drop. There are three of them but typicaly only one breaks before you let the others break by getting it fixed. They have repaired it under warranty but I told them I wanted a certified unit and 70 amps thinking it would be more substancial. They said no and gave me a whole new unit instead. They also said "by the way, no more warranty cause your problems have been caused by vibration." Well this engine runs smoother than most. This new alternator has less than 10 hours on it and now is blowing the 60 amp CB every time it is reset within about 3 minutes. Trouble shooting, the problem is internal to the alternator again. Is there another brand recomended that I can go to? I am getting tired of this and would llike to take the plane on a X-country again but am afraid to.

 

[Walt]

They also said "by the way, no more warranty cause your problems have been caused by vibration." Well this engine runs smoother than most. This new alternator has less than 10 hours on it and now is blowing the 60 amp CB every time it is reset within about 3 minutes.

Why don't you drop in and we can have a look at your installation and verify your engine vibration is either within limits or not. I give you a computer print out showing what your vibration is, this should be the "proof" you need to recover warranty.

Or if you do have excessive vibration we can fix that too!

However they may also be correct. Vibration is a major element that increases wear and tear on an engine, airframe and avionics, not to mention wear and tear on pilots and passengers. Excess vibration can shorten the life of expensive engine components, engine accessories, avionics, vacuum pumps, exhaust systems, engine baffling, spinners, brackets and more.

 

[hudgin]

Interesting that you should come up while I am looking at your web site. I have had the prop checked by Bynam and a private guy that does helicopters. They both came up with the the same results. It is .015 IPS and they say it is well within spec. The reason that I had it checked twice is that there still was a vibration that I didn't mention in my previous post. It was found and remedied before the alternator broke the 2nd time. Interestingly the prop balancing machines didn't pick it up although you could physically feel it. As I said in the post it now "feels" extremely smooth compared to a PA28-140, J3-C65 and a BE-J35 that I fly also. See this thread for more info on the prop issues. http://www.vansairforce.com/community/showthread.php?t=39612up

 

[Walt]

Interesting that you should come up while I am looking at your web site. I have had the prop checked by Bynam and a private guy that does helicopters. They both came up with the the same results. It is .015 IPS and they say it is well within spec. The reason that I had it checked twice is that there still was a vibration that I didn't mention in my previous post. It was found and remedied before the alternator broke the 2nd time. Interestingly the prop balancing machines didn't pick it up although you could physically feel it. As I said in the post it now "feels" extremely smooth compared to a PA28-140, J3-C65 and a BE-J35 that I fly also. See this thread for more info on the prop issues. http://www.vansairforce.com/community/showthread.php?t=39612up

Well .015 is certainly a very low figure for prop vib. The one thing our equipment can do that most other can't is a complete vibration survey all the way from 150 to 15,000 CPS, not just the narrow band prob vibration. This survey shows all the harmonics and any other vibration that is present like alternator bearings going bad or half order combustion imbalance vibrations (these are the ones you generally feel in the airframe).