I would appreciate some advice. Its an alternator question.I have always had a generator before.

Some fool left the master on. Handpropped but no charging. Luckily I could get home NORDO.

Mid flight home I turned master on to see if there was charging and nada. When I turned it off I saw the radio panel light flash very bright, I assume a voltage spike. My wife said she smelled burning so I left it off. I let the smoke out of something.

Charged battery and all fine but I have lost mode C. So its either the encoder or the transponder. KT76A, so I have a used one and used encoder coming.

What should I have done different? Im thinking battery pack and leave it connected for a while until some charging established.

One of the reasons I like the split master switch, and avionics master, one for battery one for alternator one for the overpriced panel

But hand flip, spin it for a bit, battery and alternator on, let it stabilize at good voltage indicated, avionics on

You want to see good volts before putting power to radios and computers etc

Unless I missed details in a previous thread, this is way to ambiguous to offer much real diagnosis. Aircraft charging systems come in hundreds of flavors, even amongst 'alternator systems'.
Many master relays are operated by the battery. Dead battery = no closed relay. Open relay = offline alternator. You can prop or jump it, and then jump the relay, but again, without knowing what flavor of alternator, and how the system is wired, it's all blind guessing.

I recently had a similar situation.
Mechanic left the OVR off of an InterAv set up. Voltage spiked and took out the external resistor, the regulator, and the field switch. Propped it, 3b MT/Pponk
Flew it home NORDO, and found enough old spares to make it happy again.
Probably scrap the whole system in time, and go Plane power, or FA'd denso.

The only funner charging systems than recip planes are the ones on turbine ag planes or MEP's, but even they can be tricked in to working most of the time.

Take care,
Rob

Rob, why didn't Ag airplane makers like Lycoming T-53 series engines? In Hueys we had a start generator, standby generator, and good Nicad battery. We got pretty good service in the woods when a battery start was really important. And why didn't some young guys I taught who changed to jets go ahead and spring for APUs at the airport, where they start 99% of the time now anyway?

Hi Contact,

Of course I'd just be speculating here, but my guess the reason the T53 wasn't adopted early on is because it is physically (and power wise) a much larger engine than the first turbine ag offerings. Almost twice as large (weight and power) as the small series Pratt or Garrett.

Leyland did actually start out with a Lyc in the AT302 (301 with a turbine on the nose) but it was the LTS101. I don't know the mil designator for that one, nor the civilian designator for the T53.
But I think Lyc turboprops are owned by Honeywell now.
My guess is Pratt made Leyland an offer he couldn't refuse and the rest is history.

The smarter guys running on muni airports are using jump pacs or apu's. And as a result enjoy cheaper HSI's. The smarter off airport guys use massive, powerful batteries. Everyone else pays with hotter starts and pricey hots.

A turbine guy needs to be careful if selecting the jump pac route. There are a couple companies who hype the hot start fear, to market their pacs, which are nothing more than a couple tiny readily available 12v batteries wired in series. The problem is we don't have the extra juice to account for the hit when the starter/generator is turning, and the terminals on them are tiny (as a result of their small physical size) serving as a choking point for the current.
A home brewed cart with two 14v race car batteries, or three 6v + one 8v golf cart batteries is a better start cart. But takes creativity, skill, talent, and patience to put together. Not a common combination in the average aggie

Sorry for the long winded thread drift.
Take care, Rob

daedaluscan wrote:I would appreciate some advice. Its an alternator question.I have always had a generator before.

Some fool left the master on. Handpropped but no charging. Luckily I could get home NORDO.

Mid flight home I turned master on to see if there was charging and nada. When I turned it off I saw the radio panel light flash very bright, I assume a voltage spike. My wife said she smelled burning so I left it off. I let the smoke out of something.

Charged battery and all fine but I have lost mode C. So its either the encoder or the transponder. KT76A, so I have a used one and used encoder coming.

What should I have done different? Im thinking battery pack and leave it connected for a while until some charging established.

An alternator won’t start charging without voltage like a generator will. You will have to give it juice from something to get it going. Even a little 9V battery will give it enough to start it charging once the engine is running. This is probably the only downside of an alternator over a generator. Next time if you battery is completely flat then don’t expect it to charge. And don’t flip the alt switch on in cruise. Bad stuff can happen. Lots of panels are placarded to not turn the alternator switch off then on again in flight.

Agreed, and again, really important to know your charging system and alternator well if you venture in to these areas.
Some alternators will need to be 'excited' some will self excite.
The field on an InterAv is 5v, striking a hot lead to it will likely fry it. A 9v battery
maybe.
All worthy stuff to know.
I run a love-joy on my Honda putt putt mix tank motors so that I can squeeze in a 1 wire ford alt between the Honda and the pump. This means the guy on the load trailer can run all the lights in the world all night long, plus the fil rite fuel pump and not smoke the truck or trailer batteries.
A few times of finding jumper cables to get the load truck home was all it took to find that solution.

All this off a 5 horse Honda putt putt whose primary job is running a mix tank.

Take care,
Rob

It’s a plane power alternator and solid state regulator. I guess I hoped the battery had enough juice to excite the alternator. Dumb move.

Pretty much steam panel with a few EI gauges. Pretty robust stuff.

Swapped out the transponder and still no mode C so encoder next.

Would someone mind explaining what can happen when we switch on the alternator in flight as mentioned above? I suppose it loads it down really fast and that’s bad on alt?

I have reset the alternator in flight numerous times and didn’t realize it was that bad.

Thanks!

If this thread was more active you'd probably see a half a dozen answers, and all different. Wheelie vs 3pt?

And that would be because not all alternators are created equal, and that doesn't even consider install variables.

Most of the ships flown in this realm have split masters, and a field switch, so the idea of bringing one online with the engine running isn't voodoo, it's just that in virtually every one of those designs, the excitement of the field is done at idle with the avionics still off. And of course shut down reversed so again isolating the avionics, and minimizing the load.

But yes, exciting the field brings it up to whatever the load requires of it. More load = bigger jump = more opportunities for spikes. When i squeeze the light trigger on a thrush illuminating 3 600w and 2 450 watt bulbs while the air cond is on, the ammeter jumps and swings wildly before settling down to it's new happy place. In the electrical world, these things happen essentially instantly, but depending on the quality and vintage of the vr, there are still spikes and 'bounces'. Irregardless of what kind of regulator and ov protection you have. Newer stuff is just better at it.

The primary concern is spiking your avionics, but a secondary concern is the sudden load on your field/armature/brushes. Kill the alternator? Probably not in anything fairly modern. Hard on it? On a Leece Neville ala MEP803a it will take out the internal diodes sooner or later, and you don't get to pick when that is. Fortunately these are readily available because that 12v/24v alt. is priced like aviation goodies.

The plane power is a great alt. It's ovr is internal and resets by cycling the field
more confusion? But the assumption is that you will reset it at start (idle) with all electrical loads off. Thus a soft start.

FWIW I am not an avionicsman, but have been in to many alternators and generators, in an effort to be as self sufficient as possible when the need arises. So far, so good.

Take care, Rob

Swapped out encoder and mode C works. Time to get it calibrated.

daedaluscan wrote:Swapped out encoder and mode C works. Time to get it calibrated.

Do you have a good local radio shop?
FWIW we've been pleased with Crown Aviation's radio work,
they're on Paine Field KPAE down here in WA.

Rob wrote: But the assumption is that you will reset it at start (idle) with all electrical loads off. Thus a soft start.

So, assuming VFR, switch avionics off, pull engine to idle, switch the field on, switch avionics back on, throttle up and Bob's your uncle?