Pursuant to a congressional request, GAO provided information on the Navy's intercooled recuperated (ICR) engine program, focusing on the: (1) Navy's need for the engine; (2) cost, schedule, and performance of the program; and (3) impact of the Navy's test and development strategies. GAO found that: (1) some Navy officials are questioning the economic viability of the ICR engine program and have raised concerns over placing ICR engines on naval destroyers, since most destroyers are equipped with reliable propulsion systems; (2) engine development costs pose a significant economic investment; (3) some officials believe the engine should not be used on naval destroyers given the small number of new U.S. destroyers involved, adequacy of current destroyer engines, high cost of incorporating the engine, uncertainty of future integration plans, and current state of ICR development; (4) the Navy has not recovered from initial recuperator failure that resulted from design, manufacturing, and quality assurance problems; (5) a contractor is instituting a recovery plan to redesign future recuperators, but the plan is not allowing sufficient time to evaluate test data prior to ordering production ICR engines; (6) the Navy has interrupted work on redesigning future recuperators because of funding reductions, contractor quality control problems, manufacturing problems, and delivery delays; and (7) the Navy needs to decide how and when it will use the Philadelphia ICR test facility and if it will test the ICR engine at sea.