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Generally, a leakage in a high pressure hose assembly can be determined if hydraulic fluid falls down through fitting
which is swaged with a rubber hose. This study tried to visualize leakage, which is considered a failure occurring often
in the hydraulic system. In the case of methods which verify leakage paths in the power steering hydraulic system
equipped with a high pressure hose assembly, three types of leakage paths, which could be seen by cutting the swaging
part, were generally found. However, it was difficult to find out leakage paths by using power steering oil. In this study,
four methods, including the thermal burn image method, the hole drilling method of fitting metal, the white paint
infiltration method, and the fluorescent infiltration method, were tried to introduce. The thermal burn image method
failed to find out the leakage path between the fitting part and the rubber part. The hole drilling method is the way to
check a leakage path on the fitting part, which doesn't need to cut a hose assembly. This method succeeds to visualize
the leakage path partially but it could not check a sequential path of leakage, either, because it needs to drill more
closely. The white paint infiltration method also could find the leakage path partially by using white paint mixed with
thinner, which was pressurized by hand pump, instead of power steering oil. This method could check the leakage path
by cutting the swaging part. The fluorescent infiltration method could verify the leakage path with naked eyes simply by
holding the cutting swaging part closely to the ray of light. Reappearance test methods in the high pressure hose
assembly, which include a hole drilling, a white paint infiltration, and a fluorescent infiltration method, can be applied
to find the failure mode and to approve the test before the mass production of the high pressure hose.
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