Definition
Items installed on an aircraft whose weights are considered fixed and unchanging for weight and balance purposes, including unusable fuel, undrainable oil, hydraulic fluid, and other fluids and components required for the aircraft to be in a ready-to-fly condition. These items are already accounted for in the aircraft's empty weight and are not added or subtracted when calculating loaded weight.
Plain English
These are the fluids and fixed items that are always on the aircraft and are already counted in its empty weight, so you don't add them in again when working out how much the aircraft weighs for a flight.
Context Anchor
Seen in weight-and-balance records, maintenance discussions, and equipment changes where small hardware items are installed, removed, or replaced.
Derivation
Standard comes from the idea of an accepted rule or measure. Here it means the part is built to a recognized specification, not just that it is common or ordinary.
Why Pilots Care
Their weights are known and tabulated, allowing accurate balance calculations while maintaining airworthiness.
Intuition Check
Do not read standard parts as meaning “any normal-looking part.” In aviation, it means parts made to a recognized specification and acceptable for aircraft use.
Example Sentence 1
The mechanic confirmed that unusable fuel and hydraulic fluid were treated as standard parts and already included in the aircraft's empty weight.
Example Sentence 2
When adding equipment, the pilot checked that all new fasteners were standard parts so the empty-weight change could be calculated directly.