Definition
A socket installed on the airframe that allows a ground power unit (GPU) or auxiliary battery cart to be plugged into the aircraft's electrical system, supplying power for engine start or ground operations without drawing on the aircraft battery.
Plain English
A plug-in point on the outside of the aircraft where you can connect an external power source to start the engine or run electrical systems on the ground.
Context Anchor
Seen during engine starting, maintenance, and ground operations when outside electrical power is connected to the aircraft.
Derivation
Receptacle comes from the Latin receptaculum, meaning 'a place to receive or hold something.' Here it is the fitting that receives the external power plug.
Why Pilots Care
Enables ground operation of avionics, lights, and other systems during preflight or maintenance without draining the aircraft battery.
Grounding Statement
Picture a clearly marked socket on the side or nose area of the aircraft where a ground power cable can be plugged in before start.
Intuition Check
Do not think of this as a normal wall outlet. It is a specific aircraft connector for approved outside electrical power, used only according to the aircraft’s procedure.
Example Sentence 1
On a cold morning the mechanic plugged the ground power unit into the external power receptacle so the engine could be started without straining the battery.
Example Sentence 2
Using the external power receptacle during a long preflight keeps the battery fully charged for the actual start.