The Department of Defense, through the Defense Logistics Agency (DLA) Aviation at Philadelphia, PA, is seeking proposals for the procurement of 25 units of a heat exchanger, specifically NSN 7R-1660-015126523-QE, REF NR 1001986-2. This procurement requires engineering source approval due to the flight-critical nature of the part, necessitating that only approved sources may submit proposals, as the technical data available does not support full and open competition. Interested vendors must provide detailed documentation as outlined in the NAVSUP Weapon Systems Support Source Approval Information Brochures, and failure to submit the required data will result in disqualification from the award process. For further inquiries, potential bidders can contact Joe H. Lewis Jr. at (215) 737-9462 or via email at JOSEPH.LEWIS@DLA.MIL.