The Department of Defense, through the Defense Logistics Agency (DLA) Aviation at Philadelphia, PA, is seeking qualified sources for the procurement of 11 units of a heat exchanger (NSN 7R-1660-015126523-QE, REF NR 1001986-2). This procurement requires engineering source approval due to the flight-critical nature of the item, necessitating that only approved sources may submit proposals, as the technical data available does not support full and open competition. The heat exchanger is vital for aircraft air conditioning, heating, and pressurizing systems, ensuring operational reliability and safety. Interested parties must contact Isabella Perrins at (215) 660-7088 or via email at ISABELLA.PERRINS@DLA.MIL for further details, and proposals must be submitted within 45 days of this notice to be considered for award.