This is a pre-solicitation notice for engineering services to resolve issues with ALR-56C and ALR-56M Radar Warning Receiver modules, structured as a sole-source award to BAE Systems Integration, Inc. The anticipated contract will have a one-year basic period with four one-year options, for a total performance period of five years. The contract will include firm-fixed-price line items for engineering services and data, plus a cost-reimbursable line item for travel. The authority for the sole-source action is that only one responsible source can satisfy the agency's requirements. This proposed action is a follow-on to an existing contract.