Leak tests are conducted by submerging a piece of material of the structure, typically an elongated sandwich composite structure in the warm water tank. The water's temperature causes the expansion of air within the structure and in the event of a crack or lamination is present, gas bubbles break out of the structure and are identified through visual examination.
The leak test is simple to set up for small components and requires a few pieces of equipment. It is restricted in its resolution by human eyes and will only result in the identification of a developing delamination or surface crack. Further go to https://flexpakinc.com/test-methods and learn about package leak testing.
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The leak test is a common NDT procedure for the majority of aerospace manufacturers. Because of its limitations most applications are based on the examination of delaminations and disbonds within sandwich composite structures, particularly the honeycomb core.
In the helium leak test the individual packages are placed in a pressurized air containing helium for a specified period of time. After that, the packages are moved into an air chamber, and the stream of helium that flows out of the leaky packaging is observed using a mass spectrometer. The stream of helium is monitored only once, and is then pumped out into the chamber.
The resolution of the measurement changes throughout the course of the day, because the background helium of the measurement area increases as time passes. It is essential to track the time of transfer after helium bombing on every device, as this delay greatly affects the measurement.
It is essential to conduct the gross leak test (bubble test in solvent) following an helium leak test in order to find devices that have very massive leaks.