14 CFR § 25.1301
Function and installation
July 13, 2020
(a) Each item of installed equipment must—
(1) Be of a kind and design appropriate to its intended function;
(2) Be labeled as to its identification, function, or operating limitations, or any applicable combination of these factors;
(3) Be installed according to limitations specified for that equipment; and
(4) Function properly when installed.
(b) EWIS must meet the requirements of subpart H of this part.
[Doc. No. 5066, 29 FR 18333, Dec. 24, 1964, as amended by Amdt. 25-123, 72 FR 63405, Nov. 8, 2007]