Definition
A combined electrical machine used on many turbine engines that functions as a starter motor to spin the engine up to a self-sustaining speed during start, and then switches role to act as a generator, producing electrical power for the aircraft once the engine is running.
Plain English
A single unit on the engine that does two jobs at different times. First it acts like a motor to get the engine spinning fast enough to start. Once the engine is running on its own, the same unit turns into a generator and produces electrical power for the airplane.
Context Anchor
Seen in turboprop electrical system descriptions, engine start procedures, and generator checks after engine start.
Derivation
The name simply combines the two roles the unit performs in sequence: starter (the device that starts the engine) and generator (the device that produces electrical current). The slash signals that one piece of hardware fills both roles.
Why Pilots Care
These units reduce aircraft weight and complexity by performing two essential functions with a single device, ensuring reliable engine starts and continuous electrical power.
Intuition Check
Do not assume starter/generators are always two separate devices. In this context, one unit can do both jobs: start the engine first, then generate electrical power afterward.
Example Sentence 1
During engine start, the starter/generator drew current from the battery to spin the compressor up to ignition speed.
Example Sentence 2
After the engine stabilized, the starter/generators supplied power to the aircraft's electrical buses.