Airplanes certificated before July 1, 1942. No certificate holder may operate an airplane that was type certificated before July 1, 1942, unless—

That airplane meets the requirements of § 121.173(c), or

That airplane and all other airplanes of the same or related type operated by that certificate holder meet the performance requirements of sections 4a.737-T through 4a.750-T of the Civil Air Regulations as in effect on January 31, 1965; or §§ 25.45 through 25.75 and § 121.173(a), (b), (d), and (e) of this title.

Airplanes certificated after June 30, 1942. Except as provided in paragraphs (c), (d), (e), and (f) of this section, no certificate holder may operate an airplane that was type certificated after June 30, 1942, unless it is certificated as a transport category airplane and meets the requirements of § 121.173(a), (b), (d), and (e).

C-46 type airplanes: passenger-carrying operations. No certificate holder may operate a C-46 airplane in passenger-carrying operations unless that airplane is operated in accordance with the operating limitations for transport category airplanes and meets the requirements of paragraph (b) of this section or meets the requirements of part 4b, as in effect July 20, 1950, and the requirements of § 121.173 (a), (b), (d) and (e), except that—

The requirements of sections 4b.0 through 4b.19 as in effect May 18, 1954, must be complied with;

The birdproof windshield requirements of section 4b.352 need not be complied with;

The provisions of sections 4b.480 through 4b.490 (except sections 4b.484(a)(1) and 4b.487(e)), as in effect May 16, 1953, must be complied with; and

The provisions of paragraph 4b.484(a)(1), as in effect July 20, 1950, must be complied with.

C-46 type airplanes: cargo operations. No certificate holder may use a nontransport category C-46 type airplane in cargo operations unless—

It is certificated at a maximum gross weight that is not greater than 48,000 pounds;

It meets the requirements of §§ 121.199 through 121.205 using the performance data in appendix C to this part;

Before each flight, each engine contains at least 25 gallons of oil; and

After December 31, 1964—

It is powered by a type and model engine as set forth in appendix C of this part, when certificated at a maximum gross takeoff weight greater than 45,000 pounds; and

It complies with the special airworthiness requirement set forth in §§ 121.213 through 121.287 of this part or in appendix C of this part.

Commuter category airplanes. Except as provided in paragraph (f) of this section, no certificate holder may operate under this part a nontransport category airplane type certificated after December 31, 1964, and before March 30, 1995, unless it meets the applicable requirements of § 121.173 (a), (b), (d), and (e), and was type certificated in the commuter category.

Other nontransport category airplanes. No certificate holder may operate under this part a nontransport category airplane type certificated after December 31, 1964, unless it meets the applicable requirements of § 121.173 (a), (b), (d), and (e), was manufactured before March 20, 1997, and meets one of the following:

Until December 20, 2010:

The airplane was type certificated in the normal category before July 1, 1970, and meets special conditions issued by the Administrator for airplanes intended for use in operations under part 135 of this chapter.

The airplane was type certificated in the normal category before July 19, 1970, and meets the additional airworthiness standards in SFAR No. 23, 14 CFR part 23.

The airplane was type certificated in the normal category and meets the additional airworthiness standards in appendix A of part 135 of this chapter.

The airplane was type certificated in the normal category and complies with either section 1.(a) or 1.(b) of SFAR No. 41 of 14 CFR part 21.

The airplane was type certificated in the normal category, meets the additional requirements described in paragraphs (f)(1)(i) through (f)(1)(iv) of this section, and meets the performance requirements in appendix K of this part.

Certain newly manufactured airplanes. No certificate holder may operate an airplane under this part that was type certificated as described in paragraphs (f)(1)(i) through (f)(1)(iv) of this section and that was manufactured after March 20, 1997, unless it meets the performance requirements in appendix K of this part.

Newly type certificated airplanes. No person may operate under this part an airplane for which the application for a type certificate is submitted after March 29, 1995, unless the airplane is type certificated under part 25 of this chapter.