Definition
A gas turbine engine in which the energy extracted from the hot exhaust gases is delivered as rotational power through an output shaft, rather than as jet thrust. The shaft drives a propeller, rotor, or accessory load through a reduction gearbox. Turboprop and turboshaft engines are both shaft turbines.
Plain English
A jet-style engine that uses its hot gases to spin a shaft instead of producing thrust out the back. The spinning shaft is then used to turn a propeller or a helicopter rotor.
Context Anchor
Seen in turbine engine discussions, especially when comparing engines that produce shaft power with engines that produce most of their push from exhaust thrust.
Derivation
‘Turbine’ comes from the Latin turbo, meaning a spinning or whirling thing. A shaft turbine is named for what it delivers — power through a shaft — rather than the jet thrust that a pure turbojet produces.
Why Pilots Care
Helicopter pilots depend on shaft turbines to supply the torque required to drive the rotor system.
Intuition Check
Do not read this as just the metal shaft inside an engine. The key idea is that the turbine’s useful output is turning power delivered through a shaft.
Example Sentence 1
The PT6 in the King Air is a shaft turbine that drives the propeller through a reduction gearbox.
Example Sentence 2
During preflight the mechanic checked the shaft turbine oil level and filter.