HB 6167.4-2014 "Environmental conditions and test methods for airborne equipment in civil aircraft, Part 4: humidity cabinet test" specifies the test conditions and methods for airborne equipment in civil aircraft in a heat and humidity environment. This standard applies to those airborne equipment that is subjected to the effects of heat and humidity environments on civil aircraft. The main purpose of the test is to assess the tolerance of equipment to natural or induced humid atmospheric environments, with a focus on corrosion, changes in mechanical, electrical, chemical and thermal performance. According to the use of equipment in different environments, the standard classifies the equipment into Class A, Class B and Class C, which correspond to the test requirements under standard heat and humidity environment, severe heat and humidity environment and external heat and humidity environment conditions, respectively, to ensure Reliability and durability of equipment in various working environments.