Code of Federal Regulations

Title 14 - Aeronautics and Space
Volume: 1Date: 2023-01-01Original Date: 2023-01-01Title: Section 27.1357 - Circuit protective devices.Context: Title 14 - Aeronautics and Space. CHAPTER I - FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION. SUBCHAPTER C - AIRCRAFT. PART 27 - AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT. Subpart F - Equipment. - Electrical Systems and Equipment.
§ 27.1357 Circuit protective devices. (a) Protective devices, such as fuses or circuit breakers, must be installed in each electrical circuit other than—
Code of Federal Regulations / Title 14 - Aeronautics and Space / Vol. 1 / 2023-01-01552
(1) The main circuits of starter motors; and (2) Circuits in which no hazard is presented by their omission. (b) A protective device for a circuit essential to flight safety may not be used to protect any other circuit. (c) Each resettable circuit protective device (“trip free” device in which the tripping mechanism cannot be overridden by the operating control) must be designed so that— (1) A manual operation is required to restore service after trippling; and (2) If an overload or circuit fault exists, the device will open the circuit regardless of the position of the operating control. (d) If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that circuit breaker or fuse must be located and identified so that it can be readily reset or replaced in flight. (e) If fuses are used, there must be one spare of each rating, or 50 percent spare fuses of each rating, whichever is greater. (Secs. 313(a), 601, 603, 604, and 605 of the Federal Aviation Act of 1958 (49 U.S.C. 1354(a), 1421, 1423, 1424, and 1425); and sec. 6(c) of the Dept. of Transportation Act (49 U.S.C. 1655(c))) [Doc. No. 5074, 29 FR 15695, Nov. 24, 1964; 29 FR 17885, Dec. 17, 1964, as amended by Amdt. 27–13, 42 FR 36972, July 18, 1977]