Loss of all electrical power 1976 PA 32R

BeelerBeeler
in General Discussion

On IFR approach recently descended through a cloud layer with Peto heat on as i set up for landing, dropped my gear, then lost all electric displays. Didn’t know if gear was down or not? Made couple of circles then dropped the gear manually. Landed safely still no electrical components of any kind with power. Has anybody else experienced the situation? As I was taxing to the ramp, all electric displays came back up?

thanks, C

Comments

  • jacobsjajacobsja
    edited 4:00PM

    Will let better experts help with troubleshooting specifics.

    Unless I am missing something, it is possible that a number of holes in the Swiss cheese are lining-up for this scenario and multiple items are feeding into the event. Or perhaps a singular item of the Master switch going bad?

    Just curious, what avionics are in the panel? All glass? Any analog gauges?

    Related, was the plane still in clouds when the power dropped? If so, by chance was it possible to determine whether the landing lights and strobes (presuming they were not turned off during the cloud transition) were still functional?

  • griff390griff390
    edited 10:30PM
    https://piperowner.org/talk/discussion/157531/loss-of-all-electrical-power-1976-pa-32r

    Beeler:

    First: that's a scary situation, and I think I speak for everyone when I say great job handling the problem and getting safely on the ground.

    Second: intermittent problems are the toughest to troubleshoot because when everything is working, there's nothing to diagnose.

    I'll reiterate jacobsja's question: When you lost your instrument displays, was there power to anything else e.g. interior lights, panel lights, strobes, etc.? If yes, that may narrow it down to the instrument/avionics bus.

    Some suggestions in no particular order: Check for a charging problem (battery, wiring, alternator, voltage regulator, overvoltage relay). If the voltage is below the minimum avionics threshold, the avionics may shut down. If the voltage is too high, the OV relay will shut down the electrical system. Check that there are no intermittent connections between the busses. It's also possible that the avionics themselves hiccuped. Did I mention that intermittent problems are difficult to trace?

    Do everything you can to reproduce the problem on the ground. If there was a complete power loss, I would begin tracing the fault from the battery. Turn the master on. Wiggle all the power wires, lightly tap the master switch, master relay, etc. If the power drops out (for instance) when you wiggle the power cable going from the battery to the master solenoid, narrow your search to the battery, wire and the solenoid, but check everything else anyway. Your electrical system may have more than 1 problem, and sometimes one problem can mask others.

    More suggestions: Check for loose connections, an intermittent master switch (as jacobsja mentioned), a bad or intermittent master relay/solenoid, etc. Continue to work forward into the aircraft's electrical system. Check the voltage on all the busses with the engine off and running.

    I'd be very leary about flying until the problem is identified, and definitely no iFR!

    Jim "Doc Griff" Griffin
    PA28 - 161
    Chicago area

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