Mikerjf

Crashed a plane due to an aileron servo going hard over during flight. Reconnected everything on the ground and cannot duplicate the problem, everything works fine with no glitches. The only thing missing on the ground is the engine vibration. What component failure would cause 1 servo out of 5 to go hard over?

Mike

dirtybird

My Feedback: (5)

What make of servo? Hitec servos will go hard over if the signal connection to the receiver is lost and the power is still connected to the servo. At least the ones I have do. I make sure to use good quality connectors on the servo extenders and the connectors are kept clean.

carcraze

That is interesting information. Is this on their digital sevo's or analog? I wonder if the failsafe is default full throw, have you tried to reset the failsafe position with the programmer and try a loss of signal?

Mat

JoeAirPort

My Feedback: (41)

This is true with 5645's. I find that out anytime I power up my rx before the tx.

dirtybird

My Feedback: (5)

I have a test rig that is used to test for transit time. It uses a switch that opens the line that carries the pulse to the servo so that I can change the pulse setting to the maximum then reapply the pulse and measure the time it takes to respond to the new setting. It works great on most servos but when testing the Hitec analog servos the minute I open the pulse circuit line the servo goes nuts. I found I had to short the pulse line to the negative line to make it stop.This just means that the Hitec servos must remain connected at all times and any loose connection on the signal line will cause trouble. I have not tried thier digital servos yet.

wisdom-seeker

This is the reason that I do a full-power run-up with the plane held captive. While at full power, I check all controls for correct throw and smoothness of operation. This has saved my bacon in the past.

XJet

I've experienced no unusual behaviour from any of my Hitec servos (digital or regular).

If you're using an FM receiver (especially the 555) and turn it on before turning on the transmitter then you will get some impressive servo-gymnastics -- but if you're using a more modern (PCM/DSP) receiver then the servos just give a tiny kick and remain still until a valid transmitter signal is received.

Mikerjf

Servo's are Futaba 3004. Checked everything before I took off and it all worked fine. Had it up for a few minutes and in a low straight pass it just started rolling.

Mike