Test hover after installing hitec HS-55 servos was interesting. The heli was making unusual altitude changes. Radical changes. Tail rotor not acting normal also. Then heli just droped out of the air like a rock. No damage was done so I was lucky. After crash inspection report is as follows:

1)Battery had full charge so no problem here (Thunder Power 11.1v 1320mA)

2)Servos working correct, swashplate and push rods setup as per manual.

3)No binding in linkages

4)Blade tracking dead on (checked before crash)

5)Flybar paddles aligned correctly with swashplate and each other (checked before crash)

6)Rotor head balanced on high point balancer before test flight.

I took off rotor head and unpluged tail rotor and was runing up main motor/mainshaft and all was okay untill motor just went dead. So what do you do? Jiggle the motor wires! Motor came back on for a bit then quit. Found the problem!
Problem was with the negative motor connectors. I cut the shrink tube off the female connector and the connector just fell off the wire! Piss poor solder job here. I had to remove all shrink tubing to check other connectors and one looked questionable. I got some new connectors at LHS and removed original connectors and installed new ones. The new ones fit together more snugly and after I solderd them on I know they are on for good. Bench test without rotor head was done and motor worked fine. In fact motor appeared to work better. This could be my imagination but at very low throttle with the motor just running,motor seemed to have a more stable rpm. Will do a test flight as soon as I can. We have a major snow/ice storm right now and I have to wait untill that passes to do proper testing.