Could someone explain beta range to me?

What happens when we set the throttle control lever to the beta range (reverse thrust) while the propeller blades are in the feathered position?

Will the blade angle change from feather to reverse pitch or will the engine over torque?

  • 1
    $\begingroup$ Throttle doesn't go negative, you set beta with pitch. This is controlled automatically when going into beta by the pitch control unit. Unless you are talking about an aircraft with full manual controls like some GA float planes? Do you have a specific aircraft you are referencing? $\endgroup$
    – Ron Beyer
    Dec 2, 2016 at 1:51
  • $\begingroup$ I am currently working with Cezh Made LET 410 UVP -E20 aircraft. But I was asking this question in general. As far as I understand; its the throttle lever used which in turn control the PCU to bring the propellers to the Reverse Pitch right? What I am asking is your Power is Idle and blades are in feather. What will happen if you pull back your Throttle Lever to Beta range? $\endgroup$ Dec 2, 2016 at 2:25
  • $\begingroup$ The PCU commands the prop into beta pitch. $\endgroup$
    – Ron Beyer
    Dec 2, 2016 at 2:30
  • $\begingroup$ Thank you. So the PCU can sufficiently change the pitch from Feather to Fine and then Reverse. $\endgroup$ Dec 2, 2016 at 2:33

1 Answer 1


Depends on they type of turboprop engine. With a straight shaft turboprop engine like a Garrett TPE331, this is not possible as feathering the props are controlled by the conditioning levers and also shut down the engines in the process. A free turbine turboprop would allow a person to feather the engines and then pull the power levers to the reverse position. Note that the propeller lever control does not set beta here, rather the power levers do, moving from idle to beta to reverse.


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