Definition
A simple leak-detection method in which soapy water is applied to a pressurized line, fitting, or component, and any escaping gas is identified by the bubbles it produces at the leak point.
Plain English
You brush soapy water onto something that holds gas under pressure. If gas is escaping, it blows little bubbles right where the leak is.
Context Anchor
Seen during aircraft maintenance when checking air, gas, or vacuum lines and their connections for leaks.
Why Pilots Care
Detects leaks that could lead to fuel loss, fire hazard, or system failure before flight.
Analogy
It is the same trick used on a bicycle inner tube: dunk it or brush it with soapy water and watch where the bubbles appear.
Grounding Statement
Escaping gas pushes through the soapy liquid and makes visible bubbles at the leak point.
Intuition Check
A soap bubble test is not a cleaning test or a strength test. It is a simple visual leak check: bubbles mean escaping air or gas.
Example Sentence 1
After replacing the oxygen line fitting, the mechanic ran a soap bubble test to confirm there were no leaks before signing off the work.
Example Sentence 2
After tightening the vacuum pump connection, the technician ran a soap bubble test to confirm the seal was tight.