Definition
On a turboprop engine, the beta control range is the portion of the power lever travel where the pilot directly controls propeller blade angle rather than engine power. It typically spans from flat pitch through reverse pitch and is used on the ground for taxi, landing rollout, and reverse thrust. Within this range, the propeller governor is no longer setting blade angle to maintain a target RPM; instead, blade angle follows the power lever position.
Plain English
It is the part of the power lever travel where moving the lever changes the propeller blade angle directly, instead of asking the engine for more or less power. Pilots use it on the ground to taxi smoothly and to slow down after landing, including selecting reverse.
Context Anchor
Seen in turboprop powerplant, propeller, and ground-handling discussions, especially when talking about power-lever rigging, taxiing, landing rollout, and reverse thrust.
Derivation
"Beta" is the second letter of the Greek alphabet and is used here as an engineering label for a secondary control mode, distinct from the normal "alpha" (governing) mode where the propeller governor controls blade angle automatically.
Why Pilots Care
Allows precise low-speed control on the ground and shortens landing rolls through reverse thrust.
Analogy
Think of the propeller blades like a fan with adjustable blades. In normal flight, the system keeps the fan working at the selected speed; in Beta mode, the power lever is more like a direct blade-angle handle.
Grounding Statement
After touchdown, moving the power lever into Beta mode changes the propeller blades so the airplane slows without relying only on the wheel brakes.
Intuition Check
Beta does not mean a trial or test version here. In this term, Beta refers to propeller blade angle control.
Example Sentence 1
After touchdown, the pilot lifted the power levers over the gate and moved them into the beta range to slow the aircraft on the runway.
Example Sentence 2
During taxi the beta mode let the crew use reverse thrust for tighter control on the ramp.