14 C.F.R. § 27.1399 Riding light.
Title 14 - Aeronautics and Space
(a) Each riding light required for water operation must be installed so that it can— (1) Show a white light for at least two nautical miles at night under clear atmospheric conditions; and (2) Show a maximum practicable unbroken light with the rotorcraft on the water. (b) Externally hung lights may be used. [Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27–2, 33 FR 964, Jan. 26, 1968]
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart F—Equipment
Lights
§ 27.1399 Riding light.