Definition
A type of fitting flare in which the end of a piece of soft metal tubing is spread outward at a 37-degree angle (or 45 degrees for some plumbing applications) into a single conical lip, which is then clamped between a fitting and a sleeve to form a leak-tight seal in a fluid line.
Plain English
The end of a metal tube is opened out into a small funnel shape one time, and that funnel-shaped lip is squeezed against a fitting to make a tight seal.
Context Anchor
Seen in aircraft maintenance when making or inspecting metal fuel, oil, brake, or other fluid lines.
Derivation
Flare comes from an old word meaning to spread or open outward, like a flame widening at its top. Single refers to the tubing being flared only once, distinguishing it from a double flare where the lip is folded back on itself for extra strength.
Why Pilots Care
A properly timed single flare prevents hard landings, excessive floating, or ballooning that can lead to runway overruns or loss of directional control.
Grounding Statement
Picture the end of a small metal tube widened outward like a tiny cone so a connector can squeeze it into a tight seal.
Intuition Check
This is not the landing flare before touchdown. Here, flare means the widened end of a tube used to make a sealed connection.
Example Sentence 1
The mechanic formed a single flare on the end of the aluminum tubing before installing the AN fitting.
Example Sentence 2
In gusty conditions the instructor demonstrated a single flare that kept the aircraft from floating too far down the runway.