Abstract: The pit cover assembly for a prefabricated pit for servicing aircraft is provided with an inverted concave cup, or hood, hingedly connected to the underside of the pit cover. The concave cup has a mouth which opens downwardly when the pit cover is closed. The cup is adapted to receive water sensitive articles or equipment. Because the mouth of the cup is directed downwardly, the inverted cup forms an air pocket or bubble chamber which will not fill with water even when the pit is flooded. The water sensitive equipment is thereby maintained in isolation from surrounding water within the air pocket, even during conditions of flooding.