14 CFR § 25.1381 - Instrument lights.
(a) The instrument lights must -
(1) Provide sufficient illumination to make each instrument, switch and other device necessary for safe operation easily readable unless sufficient illumination is available from another source; and
(2) Be installed so that -
(i) Their direct rays are shielded from the pilot's eyes; and
(ii) No objectionable reflections are visible to the pilot.
(b) Unless undimmed instrument lights are satisfactory under each expected flight condition, there must be a means to control the intensity of illumination.
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