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Blade angle control in the beta range

Aviation Mechanic Powerplant (AMP) practice question 4 of 10 on Propellers. ACS element AM.III.M.K4 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONA turboprop power lever is moved below the flight idle position into the beta range. In that range, propeller blade angle is controlled by what?

  1. AThe propeller governor
  2. BThe power lever position
  3. CTurbine inlet temperature alone
Show the answer and explanation

Correct answer: B. The power lever position

  • A — incorrect The governor schedules blade angle for flight operation; below flight idle the coordinated rpm and blade angle schedule can no longer handle the engine efficiently, so governing of blade angle is given up.
  • B — correct In the beta range of the throttle quadrant, blade angle is not governed by the propeller governor; it is controlled directly by the position of the power lever.
  • C — incorrect Turbine inlet temperature is the measure to which turboprop power changes are related in flight, but it does not position the blades in the ground handling range.

BACKGROUND

Turboprop propeller control is divided into a flight range and a ground handling range. In flight, blade angle and fuel flow for any given power lever setting follow a predetermined schedule set by the fuel control and propeller governor together. Below the flight idle power lever position that schedule can no longer handle the engine efficiently, and the ground handling range, called the beta range, is entered. In the beta range the propeller blade angle is controlled by power lever position rather than by the governor, and moving the power lever below the start position reverses propeller pitch to provide reverse thrust for rapid deceleration after landing.

STUDY TIP

Fix the dividing line in your mind: above flight idle the governor schedules blade angle, below it the power lever does, and below the start position the blades go into reverse.

KEY POINTS

  • The beta range is the ground handling range below flight idle.
  • In beta, the power lever position controls blade angle, not the governor.
  • Below the start position the pitch reverses for reverse thrust after landing.

SOURCES

  • sources/amp-powerplant/ch07.txt "Turboprop Engines & Propeller Control Systems" (beta range)
  • FAA-H-8083-32 ch07, Turboprop Engines & Propeller Control Systems
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MORE ON PROPELLERS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.