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HelicopterCompass Knight 50 ODIN 90 › Knight 50 Sport rattle noise
10-25-2009 03:43 AM  8 years agoPost 1
Xmtrflyer

rrNovice

Boston area

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During the last 8 flights or so my heli has developed a rattling noise during idle and intermittently during flight. And very recently, it has begun to run erratically, as if there was an air leak somewhere. I've checked plumbing and carb mounting for air leaks and all seemed Ok. At first, I thought it might be the clutch bell. There is some play in how the bell rotates on the starter shaft, but...I don't think that's it. Could this be the pattern failure of the rear bearing in the OS50 Hyper (blue head) I'm flying? Does the clutch bell rattle on the shaft on these helis?

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10-25-2009 04:24 AM  8 years agoPost 2
TheBum

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McKinney, TX

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Which pipe are you using? Have you tried tilting the heli forward and backward to see if anything is loose inside the pipe? Align and Outrage pipes have a history of loose baffles.

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10-25-2009 08:05 AM  8 years agoPost 3
tech3rcheli

rrApprentice

Las Vegas Nv

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There is a possibility that the baffle inside the pipe has come loose and is rattling! That would be the first thing I would check! As far as clutch bell and clutch go it shouldn't be a problem But I have seen some helicopters do it from a cause of a bad Clutch one way bearing! Check it and see if it smooth and not notchy!

Hope I could be help!

Thanks,
Devin

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10-28-2009 08:15 PM  8 years agoPost 4
Xmtrflyer

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Boston area

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Thanks for the suggestions. I shook the heli all over and all I could hear is the clunk moving from side to side. I don't know what muffler I have, but it does not look at all like the mufflers mentioned. The starter one way seems/feels good and smooth. I guess it is time to tear down the engine and replace the bearings. I'll try the stainless steel units from RCBearings, I guess.

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11-07-2009 04:50 AM  8 years agoPost 5
RAK402

rrElite Veteran

Alhambra, CA

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Rattling during idle suggests rear motor bearing.

Also, very early on, there were posts by Ade Law regarding locktiting the pinion to the pinion bearing. I never had to do this with my Knight Pro, but this was causing a noise for some fliers. I believe this was corrected in later models and certainly did not affect all Knight Pro's or Sports.

Also, the tail rotor pushrod can, under certain circumstances, vibrate when the motor is idling. My Pro did this too (most noticeable when carrying the running model out to the middle of the field to take off. This is easily detected by touching the tail pushrod while holding the modle with the engine idling (holding it in such a way that the head cannot start turning).

Team KBDD/Compass Team Manger/Experience RC/Team JR Americas/WR Field Rep

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11-11-2009 10:23 PM  8 years agoPost 6
Xmtrflyer

rrNovice

Boston area

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I've been waiting for the bearings I ordered to arrive, but meanwhile I've disassembled the engine and inspected the bearings. The front bearing was marginal. You could feel some courseness while turning it. The rear bearing was definately course. I took apart the bearing and the inner race was totally not smooth. Peened or hammered would be the description. Interestingly, the outer bearing race was perfectly smooth except for one section where it was "hammered". I think this section was sitting in the bottom arc of the connecting rod stroke. Also, that same area in the crankcase groove that the connecting rod rides in was slightly hammered.

My impression is that rust played no part in this bearing failure. The race itself was perfectly shiny. This is often cited as to why these bearings fail in these engines. I would believe that the race material simply fatigued after hard use. This created enough slop that it allowed the end of the connecting rod to hammer against the crankcase. At any rate, I strongly suspect this was the source of the rattling noise. I can't wait to install new bearing and see.

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11-24-2009 10:20 PM  8 years agoPost 7
Xmtrflyer

rrNovice

Boston area

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Just to bring closure to this thread....
I finally go the engine bearings installed. I also replaced the ring, for good measure. Broke in the engine with idling and a few tanks at hovering. Engine seems to be as good as new. End of rattle!

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HelicopterCompass Knight 50 ODIN 90 › Knight 50 Sport rattle noise
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