I have 3 Corona 120's all set up the same way, but one corona in particular is giving me a rather odd problem! all 3 Corona's are set up with the same Mega brushless motor, same lipo, same speed control. the only differeance is that the 2 good working coronas both have JR G410T Gyros and the Corona giving me problems is operating on a Futaba GY240 Gyro (I used the GY240 only because JR G410T is out of production)

But anyway, here's the problem;

When I fly the helicopter It has great stability and excellent control responses for the first 4 - 6 minutes, after that the tail rotor control slowly fades away till I have complete lack of tail control. I have almost no tail response anymore, all other cyclic & throttle controls work fine but no more tail response, it gets sluggish in the turns, then disapears all together and the heli is left spinning in circles. Then I unplug the helicopter, let it sit for 10-15 minutes, it works fine again for about 5-6 minutes, then no more tail rotor control again.
I know gyros can be sensitive to temperature change and my heli is going from my aircontioned workshop to a hot vegas outside air temp, but my other 2 good coronas can deal with the heat with no problem or change of behavior.
What Gives here ????????????????????
P.S. I've been flying it with no canopy, so extra in flight cooling dont help!
If the Gyro is at fault, I'll gladly Throw it out although its new, but I was just wondering if it could be something else causing this problem...

I had the same thing happen, but it was not the gyro, it was the tail servo. It would get hot (it was rather warm to the touch), and as it got hot, it would quit working. Try changing out the tail servo first before swapping out the gyro. From what I understand, the gyro is either a "Works, or it doesn't work" device.

Just my thoughts - Mark

Thanks Mark, I have a few brand new replacement servos laying around, I'll give it a shot....!

I agree, sounds like a servo problem.

Also if your battery is giving out and the head speed is slowing down the tail rotor becomes less effective.

Well as I said before, I will swap the servo, test fly it tonight and report my results back here.
As far as the battery is concerned, its holding up okay, its new, infact every component on this heli is new, but there is such a thing as defective parts. Head speed is consistant and strong.

Okay heres the deal, the problem was NOT the Gyro, and Not the tail rotor Servo. I took the heli out again to fly it and as soon as I started it up, the tail control was gone, I noticed that the tail rotor RPM would slow down everytime I gave a control input to the tail, and just as I figured the tail's drive train came loose and the heli was at the mercy of the main rotor's tourqe, If I hold the main rotor in my hand I can turn the tail rotor with almost no resistance. so now im going to tare down the tail section, I guess it was just a coincidence that it happened after 5 - 6 minutes everytime until the loose screw just gave out and came completely loose.

I had a similar situation on my Trex 450. My problem was the tail gear that is press fit to the shaft was slipping. This happened in the rear of the heli first, then later the forward (drive gear) did the same thing.