Starter burned up in flight, question

todd584 · April 28th, 2007, 23:50

I had something happen the other day that caused me to make an unscheduled landing. It doesn't quite add up to me so looking for some insight.

I was doing a crosscountry with my student and we smelled smoke. I didn't think too much about it at first cause I always smell something rank in that old 152. A couple minutes later the radios went dead and all we could hear on the intercom was loud static (couldn't talk to each other). Look down to see the alternator circuit breaker popped. My first thought was that there was a fire, though I never saw fire or smoke, just smelled it. We landed at an airport that we were directly over at the time to check it out. Stuck my nose in the front of the engine compartment and that's where the smell was coming from.

To sum up the rest, the airplane won't start now and a mechanic came out and replaced the starter and alternator. The burning smell was definitely from the starter and I'm pretty sure the alternator was fine as it was brand new as of two days prior.

My guess of what happened is that the starter was somehow overloading the alternator and that's what caused the breaker to pop. Maybe it was stuck engaged after we took off?
Why did the radios and intercom system fail? Battery was perfectly fine and started the airplane up with no problem after the starter was replaced. I'm thinking that the starter was drawing so much load that the alternator and battery couldn't keep up.
Afterwards one of the fuel gauges was reading full and we had below half tanks, my headset jacks/PTT don't work, and were both good beforehand.

That was a dreadful 7 hours at 1Q4

Andrew_VT · April 29th, 2007, 00:03

When you're thinking about this remember that electric motors (like the starter) are generators too. If the starter teeth stayed engaged and the whole motor started spinning with the engine then you've got a generator. I would have thought the voltage regulators and solenoids would keep this from happening but it sounds like that might have happened.

As for the electronics being screwy, maybe the spinning starter added charge to the system and things were overloaded with too much voltage...or maybe the opposite happened. With a DC system it's possible to get reverse polarities with more than one source of current, maybe you had the negitive side of the battery and alternator fighting the positive side of the starter/generator which could screw anything up!

You should know all my knowledge of DC electical systems comes from living on sailboats before you trust what I say though!

meritflyer · April 29th, 2007, 11:08

Prior to takeoff, was your ammeter or load meter showing any unusal charge?

todd584 · April 29th, 2007, 21:48

I don't remember looking that time. That's something I'm going to change in the future.

nosehair · April 30th, 2007, 10:01

Quote:

Originally Posted by todd584

I don't remember looking that time. That's something I'm going to change in the future.

Establish the habit of looking at the volt meter after starting. If the starter has stuck in the engaged position, the voltmeter will be fully pegged - and stay there.

meritflyer · April 30th, 2007, 12:05

Quote:

Originally Posted by nosehair

Establish the habit of looking at the volt meter after starting. If the starter has stuck in the engaged position, the voltmeter will be fully pegged - and stay there.

My immediate guess was this is what happened.

April 28th, 2007, 23:50	#1
todd584 Junior Member Join Date: Apr 2006 Location: Atwater, CA Posts: 155	Starter burned up in flight, question I had something happen the other day that caused me to make an unscheduled landing. It doesn't quite add up to me so looking for some insight. I was doing a crosscountry with my student and we smelled smoke. I didn't think too much about it at first cause I always smell something rank in that old 152. A couple minutes later the radios went dead and all we could hear on the intercom was loud static (couldn't talk to each other). Look down to see the alternator circuit breaker popped. My first thought was that there was a fire, though I never saw fire or smoke, just smelled it. We landed at an airport that we were directly over at the time to check it out. Stuck my nose in the front of the engine compartment and that's where the smell was coming from. To sum up the rest, the airplane won't start now and a mechanic came out and replaced the starter and alternator. The burning smell was definitely from the starter and I'm pretty sure the alternator was fine as it was brand new as of two days prior. My guess of what happened is that the starter was somehow overloading the alternator and that's what caused the breaker to pop. Maybe it was stuck engaged after we took off? Why did the radios and intercom system fail? Battery was perfectly fine and started the airplane up with no problem after the starter was replaced. I'm thinking that the starter was drawing so much load that the alternator and battery couldn't keep up. Afterwards one of the fuel gauges was reading full and we had below half tanks, my headset jacks/PTT don't work, and were both good beforehand. That was a dreadful 7 hours at 1Q4

April 29th, 2007, 00:03	#2
Andrew_VT Senior Member Join Date: Jun 2006 Location: Vermont Posts: 617	Re: Starter burned up in flight, question When you're thinking about this remember that electric motors (like the starter) are generators too. If the starter teeth stayed engaged and the whole motor started spinning with the engine then you've got a generator. I would have thought the voltage regulators and solenoids would keep this from happening but it sounds like that might have happened. As for the electronics being screwy, maybe the spinning starter added charge to the system and things were overloaded with too much voltage...or maybe the opposite happened. With a DC system it's possible to get reverse polarities with more than one source of current, maybe you had the negitive side of the battery and alternator fighting the positive side of the starter/generator which could screw anything up! You should know all my knowledge of DC electical systems comes from living on sailboats before you trust what I say though! Last edited by Andrew_VT; April 29th, 2007 at 00:09. Reason: added some stuff

April 29th, 2007, 11:08	#3
meritflyer Old Skool Join Date: Dec 2005 Location: Winchestertonfieldville Posts: 6,608	Re: Starter burned up in flight, question Prior to takeoff, was your ammeter or load meter showing any unusal charge? __________________ The simplest answer tends to be correct.

April 29th, 2007, 21:48	#4
todd584 Junior Member Join Date: Apr 2006 Location: Atwater, CA Posts: 155	Re: Starter burned up in flight, question I don't remember looking that time. That's something I'm going to change in the future.

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