If you ever have an alternator fail in flight...

[sarangan]

How many of y'all wait until the engine is running before turning on the ALT side of the Master Switch?

I teach that as standard procedure. It lets you not only check the alternator warning light, but also prevents draining the battery by unnecessarily energizing the alternator coils.

 

[smv]

I teach that as standard procedure. It lets you not only check the alternator warning light, but also prevents draining the battery by unnecessarily energizing the alternator coils.

That is my reasoning as well. I do not see it often with certificated pilots, that is why I was curious.

 

[Dan Thomas]

I teach that as standard procedure. It lets you not only check the alternator warning light, but also prevents draining the battery by unnecessarily energizing the alternator coils.

And by loading the alternator. It takes some power to turn the alternator when it's at work. That said, it's usually pretty minimal and won't make much difference unless the engine and battery are pretty cold-soaked, and every bit of extra juice is welcome and every bit of extra drag is not.

 

[NealRomeoGolf]

That is my reasoning as well. I do not see it often with certificated pilots, that is why I was curious.

My habit as well. Learned it from a book that came with my plane purchase.

 

[biplanebob]

Start engine, stabilize at idle, then turn on the alternator:
Been doing that with my homebuilt for 42years....Piper/Chrysler alternator and now Denso alternator for the last year.

 

[Timbeck2]

I had my Chrysler alternator fail on a trip to South Texas. I didn't notice the ammeter discharge because everything was working..until it wasn't. I found out when I announced my landing intentions at an uncontrolled field and the radio sounded a lot different than it normally did. I pulled up to the fuel pump and shut it down. Afterwards, I tried to start and only got a click. I hooked it up to a battery charger provided by the FBO and charged the battery enough to start the plane while I made calls to find someone to take a look at it. Then I started it up, used the radio to announce take off and departure and then shut everything off including the master switch and flew to Midland where I waited till the last minute to turn everything back on, talk to the tower and land. The mechanic found the field wire to the alternator hanging on by one strand of the wire and an automotive type ring terminal at the end of it. He replaced the ring terminal and all was well. Since then, I've changed the alternator and regulator to Plane Power and replaced the stock ammeter with an amp/voltage gauge with warning lights for drain and overcharge.

 

[Todd82]

I've now had the honor of experiencing in-flight alternator failures in both PA-28 and PA-32R Pipers. I'm not too familiar with other types so maybe this doesn't apply to all aircraft but it's definitely applied to the ones I've owned.

Both of these aircraft had the three square orange annunciators.... VAC ALT OIL. In both cases the ALT light was so dim in daylight that it was barely visible. Even cupping my hands over it to provide shade it was barely possible to tell it was on. This will NOT get your attention in the event of a failure. In the PA-28 my first warning was my GPS screen going blank as voltage dropped too low for it to stay on.

In the PA-32R I had an EDM-800 engine analyzer that started flashing the voltage at me. I dropped the gear right away and flew about 30min in VFR conditions back home, didn't lose nav or comms the entire time. I had about 11.5-11.8V all the way to landing.

Anyway what I really wanted to get across is that annunciator light is basically useless. Unless you're watching your ammeter like a hawk you probably won't notice it moving from just above 0 to 0. That engine analyzer made a HUGE difference in detecting the problem quickly. If getting one of those isn't in the cards and you have a cigarette lighter there are digital voltmeters that will plug into them and have USB charging ports on them for very reasonable prices on amazon. Better than nothing, I'd suggest something especially if you fly in IMC or are flying a retract.

I had one go at night and that ALT light was still barely noticeable.

 

[Flying_Nun]

My club Warrior is getting a new alternator at this very moment. Haven’t had a chance to fly lately so I didn’t get to experience the indicators of it going bad.


Sent from my iPad using Tapatalk

 

[pburger]

Yes, when you push the test button they are. When the alternator actually fails though, the light is nearly invisible. That's the thing I don't think most people would expect until you actually see it happen.

You might have the wrong bulb. The bulb for the ALT light should be a 6V bulb. It's a GE-328. It should be brighter than the other two when you press the test button. The OIL and VAC bulbs are standard 12V bulbs (GE-330).

 

[Rgbeard]

You might have the wrong bulb. The bulb for the ALT light should be a 6V bulb. It's a GE-328. It should be brighter than the other two when you press the test button. The OIL and VAC bulbs are standard 12V bulbs (GE-330).

Memo to me to check this - I'm wondering if mine was replaced with a GE-330.