Presolicitation notice from the Department of Defense, specifically the Department of the Navy, is seeking a heat exchanger for air repair/modification. The heat exchanger is used in aircraft air conditioning, heating, and pressurizing equipment. The government requires source approval prior to contract award due to the item's flight critical nature and inadequate technical data for acquisition through open competition. Only previously approved sources have been solicited. Interested parties must submit the necessary information for source approval. The notice provides links to the NAVSUP Weapon Systems Support (NAVSUP WSS) Source Approval Information Brochures for spares and repair. Failure to provide the required data will result in disqualification. The notice also mentions the availability of military and federal specifications and standards for reference. The award will be made based on qualification requirements at the time of award. Additional information can be obtained from the specified office.