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Old Feb 01, 2013, 03:03 PM
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United States, WA, Seattle
Joined Oct 2012
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Engine failure so easily?

I have an Great Planes Rimfire 400 28-30-950 electric motor that I use on a Great Planes PT-19. The other day I landed with a bit too much speed and overshot my desired landing point. The plane landed ok but then hit a puddle in the field and nosed over. The plane wasn't sitting in the puddle but water definitely splashed water over the nose/cowl as far as the cockfit (my front seat pilot got a little muddy). I live in Seattle to the park fields get very soggy and often have puddles (the ducks love the fields this time of year) for months at a time.

Everything looked fine - controls worked, opened the battery hatch and the battery and receiver didn't have a drop of water on them - and I didn't see streams of water running down anywhere when I picked up the model.

Next day, went through pre-flight check and then applied throttle to arm the motor - everything was fine. Then ready for take-off and gave it some gas (so to speak). Motor didn't spin and light gray spoke came out of the nose and cockpit instead. I immediately lowered the throttle and opened the cockpit to get the battery out (my first thought was the battery). Battery looked fine so I packed everything up and headed home.

On the work bench, I saw black / burnt windings on the front of the motor. I decided to power up to see what would happen. Applied throttle - no spoke but still no spinning and a little noise from the motor.

Is it reasonable that a little water splashing on the engine would cause a mini-fire and smoke so easily?

Should I have proactively - i.e. using a hair dryer / heat gun - dried out the motor right away?

I also fly in a little bit of drizzle every day. If I waited for a sunny day, I'd only fly one a month between Oct and June. The drizzle / rain here is more of a constant mist rather than real water droplets. Should I not fly with so much moisture in the air?

Thanks all - still fairly new and trying to learn the constraints of the electronic equipment.

PJ
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Old Feb 01, 2013, 03:14 PM
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United States, NJ, Frenchtown
Joined Mar 2003
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Tough call.

Water could have opened 1 of the 3 phases of the ESC.
Does the ESC have a stink or smell to it ? Did you wind up the motor during the day after pre-flight checkout ?
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Old Feb 01, 2013, 03:16 PM
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United States, NJ, Frenchtown
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Water should not hurt the motor electrically. ESC ? yes.
Bearings can rust much later.
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Old Feb 01, 2013, 03:32 PM
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Maybe more of a dirt got in the motor problem causing it to bind and draw way too much current.
Water by itself should not hurt the motor with the exception of washing out the lubrication from the bearings.
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Old Feb 01, 2013, 03:35 PM
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United States, WA, Seattle
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ESC seems fine. No stink / smell. No physical flaws. It's back in the plane now with a replacement engine (I had another one of the same engine in the parts bin) and everything is looking/working fine on the bench. I might take it out now to give it a fly.

The only indication of any issue - apart from the fact that the motor won't spin - is the blackness on some of the copper that I can see through the front of the motor.
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Old Feb 01, 2013, 03:36 PM
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Oh, and I also tried a different ESC with the original motor and the original motor still didn't spin with the other ESC.
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Old Feb 01, 2013, 04:11 PM
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Here is a pic of the motor.

Hoppy - that may be the case as the pilot had a quite a bit of dirt on him which I didn't really notice until the water dried.
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Old Feb 01, 2013, 10:14 PM
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Can you see scratches on the magnets and or stator segments? That's probably where the binding would occur.
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Old Feb 02, 2013, 12:26 AM
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Was the throttle off during the nose over?
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Old Feb 02, 2013, 12:38 PM
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United States, NJ, Frenchtown
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I always have some throttle on during a landing into any wind.
So a blade stop is death to something or the parts are electrically over currented until I get to 0 power.

USE WET FUELS !!!!
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Old Feb 02, 2013, 09:39 PM
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There probably wasn't any throttle by the time it nosed over as it had a few feet of roll before that.

I'll see if I can get a better look at the motor to if there were any signs of debris or unusual resistance.
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Old Feb 03, 2013, 04:48 AM
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United States, FL, Pompano Beach
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It's actually a motor. Big difference from an engine.
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