This is a procurement for 35 units of a flight-critical part that requires existing Government source approval prior to contract award. The Government intends to negotiate with only one pre-approved source under an exception to full and open competition. Unapproved sources may submit a proposal but must also include a complete source approval application, with the note that the approval process is typically too lengthy to delay an award. Proposals from other sources will be considered if received within 45 days of the synopsis publication. The delivery terms are FOB Origin.