Definition
Short, parallel lines used on a technical drawing to indicate that a portion of an object has been removed or shortened so the drawing fits the page, while the dimensions and proportions of the object remain accurate.
Plain English
Marks on a drawing that show a piece of the object has been left out to save space, so a long part can be shown on a smaller drawing without changing its true size.
Context Anchor
Seen in aircraft maintenance drawings, parts illustrations, and repair instructions when a long part or hidden area does not need to be drawn in full.
Derivation
From the everyday word 'break,' meaning to interrupt. The line literally shows where the drawing has been interrupted.
Why Pilots Care
Maintenance technicians must read drawings correctly. Mistaking a break line for an actual feature of the part could lead to confusion about the part's true length or shape.
Intuition Check
Do not read “break lines” as lines showing that something is broken. Here, they are drawing symbols that show part of the picture has been interrupted or shortened.
Example Sentence 1
The technician noticed the break lines on the drawing and understood that the actual control rod was longer than what appeared on the page.
Example Sentence 2
Break lines let the manual page show the full detail of the landing gear strut even though the actual part extends much longer.