This is a sole-source procurement for a flight-critical item (NSN 7R-5985-145187376-P6) where adequate technical data for competitive acquisition is unavailable, and Government source approval is required prior to award. Only previously approved sources are solicited; new sources must submit a Source Approval Brochure package with their offer, but approval processing normally cannot be completed in time to allow award. The Government intends to solicit and negotiate with only one source under FAR 6.302-1, though all responsible sources may express interest or submit capability statements. This notice is not a request for competitive proposals, but the Government will consider any proposals received within the stated period. No budget amount or performance location is specified.