This is a sole-source procurement for a flight-critical part where only previously government-approved sources are being solicited. The government intends to negotiate with only one source, but it will consider proposals from other interested parties received within 45 days of the notice's publication. Unapproved sources must submit detailed source approval information with their proposal, as the approval process is lengthy and cannot delay an award. The delivery terms are FOB Origin. The requirement is subject to Free Trade Agreements and the Buy American Act.