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Almost crashed 1/4 Scale CUB Floatplane yesterday...

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Almost crashed 1/4 Scale CUB Floatplane yesterday...

Old 04-04-2010, 09:54 AM
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snaprollinsb
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Default Almost crashed 1/4 Scale CUB Floatplane yesterday...

Ihave a 1/4 scale Cub on floats.. with a Zenoah G20ei, JRReceivers, and a Spektrum DX6i transmitter talking to a AR6200 receiver.

Ihaven't had complete trust in the radio system and have flown the plane about a dozen times. The radio has worked well so far, except that one of the elevator servos have been a little jumpy even when I'm not touching the stick.

Yesterday, Iwas making my second flight of the day (of course, with a big crowd watching), and the engine quit when Ipulled it back to flight idle (for no apparent reason.. andIhad plenty of throttle trim), and then the radio became completely unresponsive for about 3 -4 seconds...

The radio became responsive again and Iwas able to deadstick land the airplane.

Upon retrieval of the airplane, Idid a range check and the controls surfaces began to stick fully deflected and became unresponsive at times (it looked as if the airplane was doing a "robot" dance).

The RX and ignition battery levels were still very good.

Any opinions? My transmitter was not one of the ones listed in the recent recall...
Old 04-04-2010, 10:26 AM
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Villa
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

Hi snaprollinsb
On more than a few occasions, when I have had the problems you described, I have by-passed the ON/OFF switch and the problems dissapeared. I then replaced the switch. One day I realized that the std switches I used (same as come with the radio) are just too cheap. I have since changed to a switch that cost about 3 times as much, is larger/heavier, and has gold contacts, on all my planes. I have yet to have that problem again.
Old 04-04-2010, 11:02 AM
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AA5BY
 
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

I agree that the problem could be in the switch. I had one that balked twice about powering up the receiver and it quickly hit the trash can and it was not very old.

On another vein, check the fail safe position that it is not closing the throttle so far as to shut down the motor. Going to idle is what is wanted as it can sometimes be the quickest warning that you are losing control.

What you describe however is very consistent with a known quirk of the G-20 if the spark plug boot was not seated fully. Was the radio ranged checked with engine running? The G-20 is very reliable but if the spark plug boot is not fully bottomed on the plug, a great deal of interference is generated from arching within the boot and it is easy to miss that the boot is not fully seated as it takes a lot of effort to get it fully in place. A good idea is to clamp the boot onto the plug with a very small hose clamp to insure that it stays in place.

I'm thinking you may have had rfi generated at the spark plug boot and the fail safe shut the throttle fully down killing the motor.
Old 04-04-2010, 11:10 AM
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snaprollinsb
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

Thanks for your input. I will ensure that the spark plug boot is fully seated on the plug.. and I am going to take a small metal hose clamp and clamp the boot onto the plug to keep it from slipping..

I am also going to take the interior out of the airplane and double check all the wire connections.

Anything else that you guys think that I should do?

And no.. the radio was not ranged checked with the engine running.. however, when Idid the first range check a couple months ago.. Idid do it with the engine running and it did kill the engine one time...

Old 04-04-2010, 11:12 AM
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summerwind
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

well i'm glad you didn't lose your bird, but this reinforces the thoughts of using a dual switch/battery (redundancy) system YES?
Old 04-04-2010, 12:43 PM
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JohnBuckner
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

Are you using a 4.8 volt flight pack?
Old 04-04-2010, 03:31 PM
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snaprollinsb
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Default RE: Almost crashed 1/4 Scale CUB Floatplane yesterday...

4.8 volt ignition

6 volt flight pack

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