Pratt and Whitney PT6 Turbo Engine Overview

Introduction

Welcome from EAA Air Venture in Oshkosh at the Pratt and Whitney booth.
Focus on the PT6 turbo engine: reliable, powerful, advanced, and widely sold in its class.
Sponsored by Pratt and Whitney, promoting sustainable aviation.

PT6 is a reverse flow free turbine turbo prop engine.
Unlike standard jet engines, it does not have a bypass; thrust is produced by exhaust gases.
Air flows through the engine from back to front.

Air Inlet:
- Outside air sucked in through the inlet duct, often visible below the propeller.
- Air directed toward the inlet screen to protect the engine.
Low Pressure Axial Compressor:
- Comprised of 3-4 stages.
- Accelerates and increases air pressure through rotary blades and stationary stator veins.
- Example: Air pressure increases from 1 bar (15°C) at the inlet to 4 bar (180°C) after compression.
Single Stage Centrifugal Compressor:
- Further increases temperature (~300°C) and pressure (~10 bar).
- Changes air direction before entering the combustion chamber.

Combustion Chamber:
- Fuel injected through 14 nozzles ignites air-fuel mixture, creating controlled combustion.
- No spark plugs; self-ignition occurs due to hot compressed air.
- Continuous combustion from startup to shutdown.
High Pressure Compressor Turbine:
- Drives the compressor stages, spins at ~39,000 RPM.

Power Turbine:
- Extracts energy from exhaust gases; spins up to 33,000 RPM.
- Exhaust gases exit through side ducts.
Gearbox:
- Reduces the power turbine speed to 1700-2200 RPM for propeller drive (15:1 reduction ratio).
Free Turbine Design:
- Compressor turbine and power turbine operate independently, enhancing performance and safety.

Accessory Gearbox:
- Reduces RPM for mounted accessories (approx. 4000 RPM).
- Fuel control unit adjusts fuel flow.
- Oil pumps assist in lubrication.
Propeller Interface Unit:
- Controls propeller RPM.
PT6E Series Engine:
- Latest model with dual-channel electronic control for enhanced performance.