This test determines the resistance of the equipment to the effects of blowing sand and dust where carried by air movement at moderate speeds. The main adverse effects to be anticipated are:
Penetration into cracks, crevices, bearings and joints, causing fouling and/or clogging of moving parts, relays, filters, etc.
Formation of electrically conductive bridges.
Action as nucleus for the collection of water vapor, including secondary effects of possible corrosion.
Pollution of fluids.
Category D: Equipment tested as recommended in the following paragraphs for Dust test is identified as Category D. Such equipment can be installed in locations where the equipment is subjected to blowing dust in the course of normal aircraft operations.
Category S: Equipment tested as recommended in the following paragraphs for both Dust test and Sand test is identified as Category S. Such equipment can be installed in locations where the equipment is subjected to blowing sand and dust in the course of normal aircraft operations. Such location includes cockpit or any other location not intentionally protected against sand and dust exposure.
