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Home✈️Aircraft🚁HelicopterThunder TigerRAPTOR 50 › [SOLVED] Very Scary, RPM would not drop even with throttle hold
06-01-2011 07:23 AM  9 years ago
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onekon

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Los Angeles

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[SOLVED] Very Scary, RPM would not drop even with throttle hold
Sup guys,

Had a very scary moment today. I was hovering my heli and put one tank through it. landed and after 30 minutes I loaded another tank. I went to hover again and noticed that I had no smoke(very little smoke) coming out of the exhaust. I landed and the RPM would not drop, I hit the throttle hold and still nothing. I was like oh crap tank is full and motor wont shut down.

It was spinning at well above 500 RPM, I went to the side of the heli just to make sure the the throttle wasn't jammed and it wasn't. So I ran and grabbed long piece of conduit and shoved it through the skids(man was that scary) so the heli would not lift or something, there were kids around. I stood on the conduit till the gas ran out. :face I knew it wouldn't lift since pitch was negative but I landed on an inclined surface and it was very windy today.

To make a long story short, what the heck do you guys think happened here?

1. Could it be that some kid messed with the High needle while I was away talking to a buddy. (I think too lean would cause that right?)

2. Would water in the tank cause a problem like this? (I am asking cause the fuel the second time around was from another container)

3. Cracked crankcase? (don't really see any cracks)

4. Devil?

Anyway I hope you guys have some input on this as I really don't want to tear it apart to bench the motor and I sure don't want to give an arm or leg to this hobby.

Thanks to all that reply
God Bless,
Onekon
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06-01-2011 04:04 PM  9 years ago
Swoop

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Newark, DE USA

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A lean condition could have prevented it from going to idle with throttle hold but would no way explain why the engine couldn't be stopped with throttle trim (I'm assuming you tried). If the barrel is closed, it doesn't matter how rich or lean, it shouldn't run at all. That being said, either the servo was not being commanded to go to idle or something wrong with servo or throttle linkage setup. Check that the arm didn't come loose from the carb barrel.

The redline motors had sticking carb problems. What motor do you have? Fill out your profile.
Chris
X50, B320, Radix, Spartan
Titan,Kasama,MP5,Radix,JR770
Trex450SE,MavrikkG5,Phoenix35
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06-01-2011 04:26 PM  9 years ago
RaptorMan23

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Sioux City, IA

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To me it sounds like you had a carb retainer screw come out, that would allow air to come through the screw hole, simulating a wide open carburator. That would leave you helpless as you describedIf you only have to bend over once to pick it up it's a good landing.
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06-01-2011 06:57 PM  9 years ago
onekon

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Los Angeles

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Very valid point but i checked all linkages and also verified that the throttle was fully closed after the heli ran out of fuel, that was the first thing I checked.

It's an os max 50 engine. Im going to check the carb and screw again and crank case again.

Thanks for your response.
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06-01-2011 11:59 PM  9 years ago
Swoop

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Newark, DE USA

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Even if it was pulling air from somewhere, with the barrel fully closed, fuel would be shut off stopping the engine (unless the idle needle was screwed way too far out). Some way some how, that carb wasn't closing all the way. I'm not sure if the non hyper had one, but make sure there isn't a carb stop screw preventing the barrel from closing. Maybe your throttle servo has intermitten issues?Chris
X50, B320, Radix, Spartan
Titan,Kasama,MP5,Radix,JR770
Trex450SE,MavrikkG5,Phoenix35
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06-02-2011 12:17 AM  9 years ago
onekon

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Los Angeles

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I think the idle needle might have been to far IN I just turned it and it took only 1.5 turns to fully close.

So far I have checked linkages, servo, carb and needle.

I still haven't ruled out water,
Low needle and throttle linkage screw.

I really appreciate all of your responses.

God bless,
Onekon
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06-02-2011 01:58 AM  9 years ago
RCHSF

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NC

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The Throttle Arm, Hex Bolt, tightens up againt a C clip on the back side of the arm (on a O.S 50 Hyper). I have seen the Arm slip on the Butter Fly shaft going into the carb. The throttle arm will work with the servo but somtimes it will not open, or close the carb.
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06-02-2011 09:06 AM  9 years ago
onekon

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Los Angeles

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DING DING DING, RC_Flyer is the winner. It was a loose hex screw on the throttle arm, servos appeared to be functioning, Linkage was moving freely and even throttle up and down was working. it was that last 1/16 of an inch that was slipping.

I had to pull the motor out to verify this. It was just tight enough that the servo would move the arm full throttle and down to 1/4 throttle it was that remaining travel between 1/4 throttle and fully closed that the arm would slip. When I pulled the motor I used my fingers to move the throttle arm and noticed that it was slipping.

Should I use red or blue locktite to secure the nut, or you nothing at all. I have never had to tighten one before.

Thanks guys everyones input helped. God bless you all for taking the time to reply.

Onekon
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06-02-2011 02:19 PM  9 years ago
RaptorRob

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hamlin P.A.

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i always use blue works fineno babe i swear i sold my other heli to buy this one :)
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06-02-2011 02:35 PM  9 years ago
RCHSF

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NC

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I put damn epoxy on the shaft, and the arm. to make damn sure it did not move again, sometimes no matter how tight the bolt is, it will still slip.

Glade to be of service.
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Home✈️Aircraft🚁HelicopterThunder TigerRAPTOR 50 › [SOLVED] Very Scary, RPM would not drop even with throttle hold
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