This is a specialized procurement for a flight-critical part requiring existing Government source approval prior to contract award. The Government intends to negotiate with only one pre-approved source under FAR 6.302-1. Unapproved sources may submit a proposal but must simultaneously provide detailed source qualification information, with the understanding that the approval process is lengthy and an award cannot be delayed for it. Proposals from responsible sources will be considered if received within 45 days of the synopsis publication. Interested parties may also identify their capability to provide a commercial alternative within 15 days.