Abstract: A "bilge-like" valve, adapted to be mounted on the lowermost wall of an aircraft fuselage, is disclosed in which the valve has a normally open condition to drain accumulated condensate through a registering opening in the fuselage wall when the interior cabin is depressurized, and assumes a closed condition in response to a differentially higher cabin pressure relative to outside air pressure to seal off the interior of the fuselage. A valve housing retainer is affixed to the inner surface of the fuselage wall in registration with the wall opening for detachably retaining a valve housing incorporating a piston-like reciprocating valve member and biasing spring that is insertable and removable through the wall opening from the exterior of the aircrafts fuselage for ease of servicing.