Definition
A hand tool used to tighten or loosen threaded fasteners that have notches, holes, or flat sides specifically shaped to receive the tool. In British usage, the word is also used as the general term for what Americans call a wrench.
Plain English
A tool for turning nuts, bolts, or fittings. In British English, 'spanner' means the same thing Americans mean by 'wrench.' In American technical use, it specifically refers to a tool that grips a part by its notches or pin holes rather than by flat sides.
Context Anchor
Seen in aircraft maintenance instructions, tool lists, and procedures for removing or tightening special nuts, collars, rings, and fittings.
Derivation
From the German 'spannen,' meaning to stretch, tighten, or draw tight. The tool is named for what it does: it tightens things down.
Why Pilots Care
Proper use ensures fasteners remain secure, directly affecting structural integrity and flight safety.
Intuition Check
Do not assume “spanner” always means a normal open-end wrench. In aircraft maintenance, it often means a special wrench made to fit a particular round or notched part.
Example Sentence 1
The maintenance manual called for a pin spanner to remove the propeller retaining nut.
Example Sentence 2
Using the wrong size spanner on a propeller nut can round the corners and create a safety issue.