Definition
A small hole drilled at the end of a crack in a sheet-metal aircraft skin or structural component to stop the crack from spreading further. The hole removes the sharp tip of the crack, where stress concentrates, and replaces it with a smooth, rounded edge that distributes the load more evenly.
Plain English
A round hole drilled right at the tip of a crack to keep it from growing any longer. Without the hole, the sharp end of the crack acts like a tear in fabric and keeps ripping; the hole turns that sharp point into a smooth curve, which stops the tearing.
Context Anchor
Seen in aircraft maintenance, structural inspections, and repair descriptions, especially when checking metal panels or other load-carrying parts for cracks.
Derivation
From 'arrest,' meaning to stop or hold back. The term describes exactly what the hole does — it arrests (stops) the progress of the crack.
Why Pilots Care
Stops small cracks from becoming structural failures that could lead to in-flight problems or grounding of the aircraft.
Analogy
It works the same way as drilling a small hole at the end of a tear in a tarp before it rips further across. The sharp point of the tear is what keeps it spreading; round it off and the tear stops.
Intuition Check
Do not assume a crack arrester makes a cracked part fully repaired by itself. It is meant to stop or slow the crack from spreading; the damage still has to be inspected and handled correctly.
Example Sentence 1
The mechanic drilled a crack arrester at the end of the hairline crack in the wing skin to prevent it from spreading.
Example Sentence 2
Regular inspections often find small cracks that are stopped with crack arresters to keep the aircraft airworthy.