How, exactly, does that no back spring function?

[RobertE]

Many of us are struggling with the decision to replace this little spring, or not.  Does anyone know exactly how the spring functions?  Is it stressed with ever gear extension and retraction?  Big stress or small?  Or does it just come into play as a fail safe if some odd happens?

thanks.

[nels]

Is that the spring that makes the landing gear shutter when extended or retracted?

[RobertE]

Boy, I don't know.  I'd just like to know what the thing does.  We're all trying to decide whether replacing it is worth the terribly invasive procedure required to do so so.

[M20S Driver]

33 minutes ago, RobertE said:

Boy, I don't know.  I'd just like to know what the thing does.  We're all trying to decide whether replacing it is worth the terribly invasive procedure required to do so so.

The spring transfers the motor torque for extension and retraction on the Eaton actuators.  It is also used when the manual extension is done.  if it fails in the gear up or partial extension position, there is no way to extend the gear.  

I just changed mine after 1100 hours and will do it again at around 2100 hours.  Don Kaye has the pictures and more info on his website  www.donkaye.com.

[RobertE]

Thanks for the input.  Does that little spring really transmit all the torque from the motor to the mechanism?  That just seems like too small a spring for the job.  Odd design.

 

[M20S Driver]

4 hours ago, RobertE said:

Thanks for the input.  Does that little spring really transmit all the torque from the motor to the mechanism?  That just seems like too small a spring for the job.  Odd design.

 

Yes.  The little spring is transmitting the motor torque to the mechanism.  

My No Back Spring after 1150 hours was like new on one end and was showing edge erosion and deep scratches on the second end. I also had to change the manual extension clutch since it was worn out.  

[201er]

My mech discovered that mine hadn't been replaced in over 2000 hours. We just took the good fortune of not having it fail and replaced it on the spot.

[Cyril Gibb]

On 2016-04-15 at 7:32 PM, nels said:

Is that the spring that makes the landing gear shutter when extended or retracted?

Eaton actuator documents state that gear shutter/shudder is due to incorrect shimming of the no-back spring housing causing out of spec rotational torque.  I'd get it looked at.