need help with new alternator noise

Lan Vinh Do · #1 08-12-2013, 09:00 PM

Hi
I made a flight over the water today. Half way me and my passenger notice what we tought was a alarm in the headset. . It was a high frequency that was beeping at a speed around twice per second. I look at my ELT, Co2 detector, my eis and everything was fine. Turn strobe and nav light off ... no change. It's really a new noise and it's not continous ( i have 250 hre myself on the aircraft)

Then i turn off my alternator and the sound stop but came back as soon as i turn it on. It was still charging, amp was showing 23 , voltage 14.6
The plane have 350hre. It's the stock alternator that was coming with the FWF of the rv-10 in 2005.
on the approach and landing, the frequency and the tone of the noise went down with the rpm but it's still there at idle.
could notice a hum in my headset for the first 2min after engine start but it was stoping by itself after. Not sure it'S the same kind of noise.

i think i will take the alternator off and have it rebuilt. Any Idea before i do this?

Thank You

Mich48041 · #2 08-13-2013, 06:47 AM

Check ALL electrical connections to make sure they are clean and tight, not just the alternator but also the audio system. Especially check grounds.
Joe Gores

Lan Vinh Do · #3 08-13-2013, 08:21 AM

I will do that. I was curious about the fact that it's not a continuous sound. In my older plane I could hear the strobe. But this is really regular and vary exactly with the rpm. Really sound like an alarm. Not sure a bad ground would do this but I will check everything.

cajunwings · #4 08-13-2013, 09:46 AM

Try to get it bench checked. You may have a diode breaking down.

Don Broussard
RV 9 Rebuild in Progress

Ironflight · #5 08-13-2013, 11:31 AM

Don't forget to check simple stuff - what changed? Did your passenger plug in their headset? Could they have accidentally disturbed the jacks such that the isolating washer shifted and the jack is creating a ground loop? If I get a new symptom, I check what just happened that might cause it.

Paul

turbo · #6 08-13-2013, 01:54 PM

had the same situation a couple years ago. added a cheap gadget to the alternator and been fine since then.

Lan Vinh Do · #7 08-13-2013, 02:45 PM

I will remove it and have it bench test. I am more concern if it's a sign that the alternator will fail soon. I am flying IFR. I have my back-up but still want to be confident in the plane. The noise..I would like to find the source but can live with it.
My headset jack are on the overhead console ( fiberglass) so not worry for isolation.

Thank you for all the advice. Any new idea are welcome.

PS. When I was at the ILes de la Madeleine airport yesterday, there was 4 RV, one lancair and one money. 5 homebuilt for one certified. I love this.

Sam Buchanan · #8 08-13-2013, 03:12 PM

Quote:

Originally Posted by turbo

had the same situation a couple years ago. added a cheap gadget to the alternator and been fine since then.

Ok...I'll bite, got a similar situation. What was the "cheap gadget"?

Lan Vinh Do · #9 08-15-2013, 07:57 AM

Had the alternator bench test this morning.
A short in the rectifier.

When i took a look to my engine data on savvy, my voltage was always 14.4 to 14.5 but the last flight it was 14.7 to 14.8v.

It will be ready with a new rectifier this afternoon and 50$. ready to fly tonight.
My hangar neighbour is jealous. It would have grounded his piper for 2 week and probably 500 or more$.