An equipment unit for installation in an aircraft includes an enclosure, in which at least one movable mechanical element is arranged, a supply duct, and a non-return valve, wherein the enclosure includes an inflow port and an outflow port, wherein the supply duct is connected to the inflow port, wherein the non-return valve is connected to the outflow port, wherein the supply duct is connectable to a source of heated air providable in the respective aircraft, and wherein the enclosure is designed that air supplied through the supply duct enters the enclosure through the inflow port, picks up moisture from inside the enclosure and exits through the outflow port.