RTCA DO-160 – Section 10.0 – Waterproofness
These tests determine whether the equipment can withstand the effects of liquid water being sprayed or falling on the equipment or the effects of condensation.
These tests are not intended to verify performance of hermetically sealed equipment.
Therefore, hermetically sealed equipment may be considered to have met all waterproofness requirements without further testing.
Equipment shall be considered hermetically sealed when the seal is permanent and airtight.
DO-160 is a standard for environmental test on avionics equipment published by RTCA, the Radio Technical Commission for Aeronautics. The DO 160 G was amended and now all guideline inside it are replaced by the DO 357.