Alternator not coming on

Discussion in 'Maintenance Bay' started by DesertNomad, Sep 12, 2019 at 7:29 PM.

  1. DesertNomad

    DesertNomad Pattern Altitude

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    A few days ago in Indiana, I had the master switch on my Dakota replaced because the plastic battery switch (left side) cracked.

    https://www.pilotsofamerica.com/community/threads/piper-dakota-broken-split-master-switch.121254/

    After it was replaced, I flew about 3 hours to upstate New York (KELM). Today I departed KELM for a fuel stop in Rome, NY (KRME) about 40 minutes away (100LL for $3.86!). All that was fine.

    After getting fuel and starting up, I was not showing any load on the ammeter gauge and my JPI 830 indicated 12.1 volts (not charging). I turned off all the avionics and cycled the right side of the switch (ALT) with no change. I told ground I need to reposition to the ramp to investigate. Once over there I left the avionics on and cycled the ALT switch whereupon it came up and indicated a correct draw on the ammeter and the JPI read 13.7 volts. All good. I then cycled the ALT switch a few more times and got good results. Everything seeming ok, I flew to Lebanon, NH where I am now.

    In all this I don't think the ALT annunciator light ever came on but I am not 100% sure.

    I hope in the morning it will work ok. I am a bit suspicious that there is something wrong in the switch since that was very recently replaced. The alternator belt is tight and I have never had this happen in the 4.5 years and 500 hours that I have owned the airplane.

    Has anyone else had the alternator not come on like this and fixed with a cycle (or two) of the switch?
     
  2. hindsight2020

    hindsight2020 En-Route

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    Occam's Razor. Sounds like the switch replacement job wasn't a good one. Certified aviation FTW.
     
  3. DesertNomad

    DesertNomad Pattern Altitude

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    I have written to the guys that replaced it. They are a highly respected shop and the largest Piper dealer in the world (Muncie Aviation).
     
  4. hindsight2020

    hindsight2020 En-Route

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    I meant the switch itself. Not sure how the procurement of the part came about, but it might be worthwhile asking for a replacement on the house.
     
  5. DesertNomad

    DesertNomad Pattern Altitude

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    The switch is a brand new part from Piper (not a salvage or used part) as Muncie is a Piper dealer and had one in stock.
     
  6. MBDiagMan

    MBDiagMan En-Route

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    Use a DVM on about a 20 Volt scale and measure the voltage Across the terminals of the switch while on. It should measure zero Volts or maybe a milliVolt. If it is not dropping Voltage across the switch while flowing current, there is nothing wrong with the switch, as long as it will also turn off of course.
     
  7. DesertNomad

    DesertNomad Pattern Altitude

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    I'll see what happens when I start it up today. We're on a large cross country trip and trying to pick airports that have maintenance available on the field.
     
  8. Dan Thomas

    Dan Thomas Final Approach

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    Could be nothing more than a loose terminal screw on the new switch.
     
  9. DesertNomad

    DesertNomad Pattern Altitude

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    That was my thought. It worked fine today for a cold start and a repositioning start after getting fuel. Fingers crossed.