RTCA DO-160 – Section 6.0 – Humidity
This test determines the ability of the equipment to withstand either natural or induced humid atmospheres. The main adverse effects to be anticipated are:
Change of equipment characteristics resulting from the absorption of humidity.
Electrical (conductors and insulators)
Chemical (hygroscopic elements)
Category A – Standard H. Environment
It ordinarily provides an adequate test environment for equipment intended for installation in civil aircraft, non-civil transport aircraft and other classes, within environmentally controlled compartments of aircraft in which the severe humidity environment is not normally encountered.
Category B – Severe H. Environment
Equipment installed in zones not environmentally controlled may be required to be operated under conditions such that it is subjected to a more severe atmospheric humidity environment for periods of time in excess of that specified for the standard humidity environment.
Category C – External H. Environment
Equipment may be required to be operated under conditions such that it is subjected to direct contact with outside air for periods of time in excess of that specified for the standard humidity environment.