14 CFR 23.1557 - Miscellaneous markings and placards.
(a)Baggage and cargo compartments, and ballast location. Each baggage and cargo compartment, and each ballast location, must have a placard stating any limitations on contents, including weight, that are necessary under the loading requirements.
(b)Seats. If the maximum allowable weight to be carried in a seat is less than 170 pounds, a placard stating the lesser weight must be permanently attached to the seat structure.
(c)Fuel, oil, and coolant filler openings. The following apply:
(1) Fuel filler openings must be marked at or near the filler cover with -
(i) For reciprocating engine-powered airplanes -
(A) The word “Avgas”; and
(B) The minimum fuel grade.
(ii) For turbine engine-powered airplanes -
(A) The words “Jet Fuel”; and
(B) The permissible fuel designations, or references to the Airplane Flight Manual (AFM) for permissible fuel designations.
(iii) For pressure fueling systems, the maximum permissible fueling supply pressure and the maximum permissible defueling pressure.
(2) Oil filler openings must be marked at or near the filler cover with the word “Oil” and the permissible oil designations, or references to the Airplane Flight Manual (AFM) for permissible oil designations.
(3) Coolant filler openings must be marked at or near the filler cover with the word “Coolant”.
(d)Emergency exit placards. Each placard and operating control for each emergency exit must be red. A placard must be near each emergency exit control and must clearly indicate the location of that exit and its method of operation.
(e) The system voltage of each direct current installation must be clearly marked adjacent to its exernal power connection.