47 CFR §73.1225

1. (a)The licensee of a broadcast station shall make the station available for inspection by representatives of the FCC during the station's business hours, or at any time it is in operation.
2. (b)In the course of an inspection or investigation, an FCC representative may require special equipment tests, program tests or operation with nighttime or presunrise facilities during daytime hours pursuant to § 0.314, part 0, of the FCC rules.
3. (c)The following records shall be made available by all broadcast stations upon request by representatives of the FCC.
   1. (1)Equipment performance measurements required by §§ 73.1590 and 73.1690.
   2. (2)The written designations for chief operators and, when applicable, the contracts for chief operators engaged on a contract basis.
   3. (3)Application for modification of the transmission system made pursuant to § 73.1690(c).
   4. (4)Informal statements or drawings depicting any transmitter modification made pursuant to § 73.1690(e).
   5. (5)Station logs and special technical records.
4. (d)Commercial and noncommercial AM stations must make the following information also available upon request by representatives of the FCC.
   1. (1)Copy of the most recent antenna or common-point impedance measurements.
   2. (2)Copy of the most recent field strength measurements made to establish performance of directional antennas required by § 73.151.
   3. (3)Copy of the partial directional antenna proofs of performance made in accordance with § 73.154 and made pursuant to the following requirements:
      1. (i)Section 73.68, Sampling systems for antenna monitors.
      2. (ii)Section 73.69, Antenna monitors.
      3. (iii)Section 73.61, AM direction antenna field strength measurements.