47 CFR § 13.19 - Operator's responsibility.
(a) The operator responsible for maintenance of a transmitter may permit other persons to adjust that transmitter in the operator's presence for the purpose of carrying out tests or making adjustments requiring specialized knowledge or skill, provided that he or she shall not be relieved thereby from responsibility for the proper operation of the equipment.
(b) In every case where a station operating log or service and maintenance log is required, the operator responsible for the station operation or maintenance shall make the required entries in the station log. If no station log is required, the operator responsible for service or maintenance duties which may affect the proper operation of the station shall sign and date an entry in the station maintenance records giving:
(1) Pertinent details of all service and maintenance work performed by the operator or conducted under his or her supervision;
(2) His or her name and address; and
(3) The class, serial number, and expiration date (if applicable) of the license when the FCC has issued the operator a license; or the PPC serial number(s) and date(s) of issue when the operator is awaiting FCC action on an application.
(c) When the operator is on duty and in charge of transmitting systems, or performing service, maintenance or inspection functions, the license or permit document, or a photocopy thereof, or a copy of the application and PPC(s) received by the FCC, must be posted or in the operator's personal possession, and available for inspection upon request by a FCC representative.
(d) The operator on duty and in charge of transmitting systems, or performing service, maintenance or inspection functions, shall not be subject to the requirements of paragraph (b) of this section at a station, or stations of one licensee at a single location, at which the operator is regularly employed and at which his or her license, or a photocopy, is posted.