Sikorsky Aircraft Corp., Stratford, Connecticut, is awarded a $47,000,000 modification (P00009) to a previously awarded cost-plus-fixed-fee, firm-fixed-price, indefinite-delivery/indefinite-quantity contract (N0001923D0015). This modification increases the contract ceiling for compatibility assessments and engineering models, cost reduction analysis, software support, correction of software deficiencies and enhancements, service life extension analysis, and flight test supporting follow-on test and evaluation activities in support of sustainment efforts for the H-53 helicopter for Foreign Military Sales customers. Work will be performed in Stratford, Connecticut (97%); and various locations within the continental U.S. (3%), and is expected to be completed in March 2028. No funds will be obligated at the time of award; funds will be obligated on individual orders as they are issued. This contract was not competed. Naval Air Systems Command, Patuxent River, Maryland, is the contracting activity.