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A couple of weeks ago, I was going to take the plane and a passenger on a short trip. Hadn't flown in a couple weeks, so I got out to the field early, did a good preflight, then made a short hop to a nearby field with cheaper gas to top off and just make sure everything was ready to go. Everything was normal on the hop over and back to my home base.
After loading up my passenger, we taxied for takeoff. I skipped the runup since I had just checked it out, but as we rolled down the runway I glanced at the engine monitor and noticed low volts. Checked the ammeter, and it was on 0. Looked like an alternator failure. Must have just happened, because it was fine on the two short hops I'd just taken.
I aborted the takeoff, taxied off to a nearby parking area, and did some simple troubleshooting: Tried toggling the master--no change. Tried cycling the 60A alternator cb--no change. Gave up, and taxied over to my mechanic's hangar, dropped it off, and drove to our destination, instead.
My mechanic pulled the alternator and had it checked at a local shop, who said the diodes had failed. I hadn't replaced (or serviced) the alternator in the 15 years I'd owned the plane, so requested it be replaced with a Plane Power AL12-C60 kit, which the mechanic did.
When he tested it after the install, the behavior was slightly different from what I saw, but not good: Amps come up on the ammeter and volts look good for a few seconds, and then it goes offline (ammeter to 0 and volts to battery voltage). (This is how he reported it to me--I have not seen the behavior in person.)
So they suspected a faulty voltage regulator / ACU (Zeftronics R15V0N). They replaced it with a new unit...same result.
So now they're scratching their heads, and I don't have any good ideas either. They swear they've got the alternator terminals wired correctly.
Any suggestions?
After loading up my passenger, we taxied for takeoff. I skipped the runup since I had just checked it out, but as we rolled down the runway I glanced at the engine monitor and noticed low volts. Checked the ammeter, and it was on 0. Looked like an alternator failure. Must have just happened, because it was fine on the two short hops I'd just taken.
I aborted the takeoff, taxied off to a nearby parking area, and did some simple troubleshooting: Tried toggling the master--no change. Tried cycling the 60A alternator cb--no change. Gave up, and taxied over to my mechanic's hangar, dropped it off, and drove to our destination, instead.
My mechanic pulled the alternator and had it checked at a local shop, who said the diodes had failed. I hadn't replaced (or serviced) the alternator in the 15 years I'd owned the plane, so requested it be replaced with a Plane Power AL12-C60 kit, which the mechanic did.
When he tested it after the install, the behavior was slightly different from what I saw, but not good: Amps come up on the ammeter and volts look good for a few seconds, and then it goes offline (ammeter to 0 and volts to battery voltage). (This is how he reported it to me--I have not seen the behavior in person.)
So they suspected a faulty voltage regulator / ACU (Zeftronics R15V0N). They replaced it with a new unit...same result.
So now they're scratching their heads, and I don't have any good ideas either. They swear they've got the alternator terminals wired correctly.
Any suggestions?
