jbranch1

I recently crashed my hawk 4 when my engine flamed out inverted.After putting it back together it wouldn't lift off. After checking with my pitch gauge and every other thing I could think of ,I ran the engine up hit throttle hold with full pitch and watched as the servo gradually added more pitch as the head speed slowed.So I know what your thinking bad servo,I changed it with a brand new one futaba s3003 .It still didn't work.A simple fix would be a high torque servo, but why isn't the standard servo strong enough now when it was before.There is no binding ,everything moves freely .I checked the book and I put everything back together like it's supposed to be.
Has anyone had this problem?I'm sure it's probably something simple, but I can't figure it out.

GRANT ED

If your 100% sure there is no binding then it will be a matter of eliminating potential trouble makers. I would check your reciever. Possibly it was damaged in the crash. How does the servo run when its not connected to anything compared to another servo?

jbranch1

I hooked up another rx to it to see if that was it .I still got the same problem.
I'll probably put a hitec 605 on it , but I just don't see why I've been flying all this time with just a standard servo.
Thanks

jbranch1

Oh the servo works just fine and seems to have the same power as other servo's just from me holding it and seeing how much it takes to stall it.

jbranch1

I knew it was simple.I should have read the faq at century's website.Hope this helps anyone else who's done this.
from century FAQ
"Q. At full power, why does my Hawk not come off the ground?

P. This is a very common occurance after a customer has crashed for the first time, has bent the feathering spindle and replaced it.

A. Most of the time, the 2 washers, that go inside the main rotor blade holders, at the end of the feathering shaft are reversed. In step #4 of the Hawk IV instruction manual, the M4x10 Flat washer must be installed first against the ball bearing. Next, the M4x12 flat washer in installed on the outside before the M4 Locknut.

What is actually happening when this is the case? By reversing the washers, the larger washer will touch the inside and outside race of the outboard ball bearing, effectively locking the bearing and locking the collective pitch at the threshold RPM. What makes this difficult to troubleshoot for the beginner is that on the ground at idle or off, the collective system is super smooth. Only when the main rotor head speed is above 1/2 throttle the centrifigal force from the main blades is high enough to lock the bearing.

Other reasons may be because the pitch is not set properly, the engine may be set too lean or too rich or not enough RPMs.[top]