14 CFR 171.157 - Performance requirements.
(a) The DME must meet the performance requirements set forth in the “International Standards and Recommended Practices. Aeronautical Telecommunications, Part I, Paragraph 3.5” (Annex 10 to the Convention of International Civil Aviation).
(b) It must be shown during ground inspection of the design features of the equipment that there will not be conditions that will allow unsafe operations because of component failure or deterioration.
(c) The monitor must be checked periodically, during the in-service test evaluation period, for calibration and stability. These tests and ground tests of the functional and performance characteristics of the DME transponder must be conducted in accordance with the maintenance manual required by § 171.161(b).
(d) Flight inspection to determine the adequacy of the facility's operational performance and compliance with applicable “Standards and Recommended Practices” must be accomplished in accordance with the “U.S. Standard Flight Inspection Manual.”