14 C.F.R. § 38.1 – Applicability.

(a) Except as provided in paragraph (c) of this section, an airplane that is subject to the requirements of 40 CFR part 1030 may not exceed the fuel efficiency limits of this part when original type certification under this title is sought. This part applies to the following airplanes:
1. (1) A subsonic jet airplane that has—
  1. (i) Either—
    1. (A) A type-certificated maximum passenger seating capacity of 20 seats or more;
    2. (B) A maximum takeoff mass (MTOM) greater than 5,700 kg; and
    3. (C) An application for original type certification that is submitted on or after January 11, 2021;
  2. (ii) Or—
    1. (A) A type-certificated maximum passenger seating capacity of 19 seats or fewer;
    2. (B) A MTOM greater than 60,000 kg; and
    3. (C) An application for original type certification that is submitted on or after January 11, 2021.
2. (2) A subsonic jet airplane that has—
  1. (i) A type-certificated maximum passenger seating capacity of 19 seats or fewer;
  2. (ii) A MTOM greater than 5,700 kg, but not greater than 60,000 kg; and
  3. (iii) An application for original type certification that is submitted on or after January 1, 2023.
3. (3) A propeller-driven airplane that has—
  1. (i) A MTOM greater than 8,618 kg; and
  2. (ii) An application for original type certification that is submitted on or after January 11, 2021.
4. (4) A subsonic jet airplane—
  1. (i) That is a modified version of an airplane whose type design was not certificated under this part;
  2. (ii) That has a MTOM greater than 5,700 kg;
  3. (iii) For which an application by the type certificate holder for a type design change is submitted on or after January 1, 2023; and
  4. (iv) For which the first certificate of airworthiness is issued with the modified type design.
5. (5) A propeller-driven airplane—
  1. (i) That is a modified version of an airplane whose type design was not certificated under this part;
  2. (ii) That has a MTOM greater than 8,618 kg;
  3. (iii) For which an application by the type certificate holder for a type design change is submitted on or after January 1, 2023; and
  4. (iv) For which the first certificate of airworthiness is issued with the modified type design.
6. (6) A subsonic jet airplane that has—
  1. (i) A MTOM greater than 5,700 kg; and
  2. (ii) Its first certificate of airworthiness issued on or after January 1, 2028.
7. (7) A propeller-driven airplane that has—
  1. (i) A MTOM greater than 8,618 kg; and
  2. (ii) Its first certificate of airworthiness issued on or after January 1, 2028.
(b) The requirements of this part apply to an airplane for which an application for a change in type design is submitted that includes a modification that meets the change criteria of § 38.19. A modified airplane may not exceed the applicable fuel efficiency limit of this part when certification under this chapter is sought. A modified airplane is subject to the same fuel efficiency limit of § 38.17 as the airplane was certificated to prior to modification.
(c) The requirements of this part do not apply to:
1. (1) Subsonic jet airplanes having a MTOM at or below 5,700 kg.
2. (2) Propeller-driven airplanes having a MTOM at or below 8,618 kg.
3. (3) Amphibious airplanes.
4. (4) Airplanes initially designed, or modified and used, for specialized operations. These airplane designs may include characteristics or configurations necessary to conduct specialized operations that the FAA and the United States Environmental Protection Agency (EPA) have determined may cause a significant increase in the fuel efficiency metric value.
5. (5) Airplanes designed with a reference geometric factor of zero.
6. (6) Airplanes designed for, or modified and used for, firefighting.
7. (7) Airplanes powered by reciprocating engines.