14 C.F.R. § 25.1383 – Landing lights.

(a) Each landing light must be approved, and must be installed so that—
1. (1) No objectionable glare is visible to the pilot;
2. (2) The pilot is not adversely affected by halation; and
3. (3) It provides enough light for night landing.
(b) Except when one switch is used for the lights of a multiple light installation at one location, there must be a separate switch for each light.
(c) There must be a means to indicate to the pilots when the landing lights are extended.