Presolicitation notice from the Department of Defense, Department of the Navy, is seeking a valve assembly for environmental purposes. This valve assembly is used in the repair and modification of aircraft air conditioning, heating, and pressurizing equipment. The notice specifies that the valve assembly requires engineering source approval to maintain its quality and that only approved sources have been solicited. The item is flight critical and the technical data available is not determined adequate for acquisition via full and open competition. Interested parties must submit the required information for source approval along with their proposal. The notice also provides links to source approval information brochures and other relevant documents. The proposed contract action is for supplies or services for which the Government intends to solicit and negotiate with only one source. All responsible sources may identify their interest and capability to respond to the requirement or submit proposals, quotations, or capability statements.