; (2) shall include an assessment of whether a legacy system is an outdated, insufficient, unsafe, or unstable legacy system; (3) with respect to any legacy systems identified in the audit as an outdated, insufficient, unsafe, or unstable legacy system, shall include— (A) an analysis of the operational risks associated with using such legacy systems; (B) recommendations for replacement or enhancement of such legacy systems; and (C) an analysis of any potential impact on aviation safety and efficiency; and (4) shall include recommended performance metrics by which the Administrator can assess the circumstances in which safety-critical communication, navigation, and surveillance aviation infrastructure within the national airspace system can remain in operational service, which take into account— (A) the expected lifespan of such aviation infrastructure; (B) the number and type of mechanical failures of such aviation infrastructure; (C) the average annual costs of maintaining such aviation infrastructure over a 5-year period and whether such costs exceed the cost to replace such aviation infrastructure; and (D) the availability of replacement parts or labor capable of maintaining such aviation infrastructure. (c) Deadline Not later than 15 months after the date of enactment of this Act, the audit required under subsection (a) shall be completed. (d) Report Not later than 180 days after the audit required under subsection (a) is completed, the Administrator shall provide to the appropriate committees of Congress a report on the findings and recommendations of such audit, including— (1) an inventory of the legacy systems in use; (2) an assessment of the operational condition of the legacy systems in use, including the interoperability of such systems; (3) the average age of such legacy systems and, for each such legacy system, the intended design life of the system, by type