FAA FAR index in relation to Propliners

The dwindling numbers of vintage transports (Propliners) in the U.S operate according to regulations stipulated by the F.A.A.: Flight Aviation Rules (FAR).
The permit issued refers to a Federal Aviation Administration's "Part" number, which describes the bounderies of (air transport) operating permit: passengers and/or cargo, national or international and such like. It also describes in detail matters like Manual Requirements, Aircraft Requirements, Airplane Performance Operating Limitations, Special Airworthiness Requirements, Instrument and Equipment Requirements and much more.
I was frequently confused by the references and below I have attempted to sort them out whereas they refer to the "Propliners" in which I have an interest. The regulations do not refer to engine types, but rather the size of the transport equipment; however, when an Aircraft Operator is being referred to as a "Part 121 Operator" this shortlist might be useful as a quick reference.

Part 91 General Operating and Flight Rules
Part 121 Operating requirements: Domestic, flag, and supplemental operations
Part 125 Certification and operations: Airplanes having a seating capacity of 20 or more passengers or a maximum payload capacity of 6,000 pounds or more; and rules governing persons on board such aircraft
Part 129 Operations: Foreign air carriers and foreign operators of U.S.-registered aircraft engaged in common carriage
Part 135 Operating requirements: Commuter and on demand operations and rules governing persons on board such aircraft
Part 137 Agricultural Aircraft Operations

Marc Hookerman knows how to describe how an operator can change within these regulation to serve changing marketing conditions:
Florida Air Transport has actually recently started operating under Part 129. They were 125 (payloads of 6000lbs or more), but because they needed foreign air carrier status to start the Turks runs again, they needed to move up to 129 which makes them foreign operator (the Turks Air part of the equation) of US registered aircraft for common carriage. The days of loosely monitored, general Part 91 operations are few and far between because of new restrictions and heavy monitoring by the FAA and DoT. Part 91 is general flight operations, 125 is 20+pax or 6000lbs+ max payload, and 129 is foreign common carriage (which acts as a piggy back on 125).
Thanks Marc !

Jeff Holtz, flying with Rhoades added some interesting information to all this:
You might be interested in adding Part 135, which applies to cargo capacity of 7500lbs or less, and I do not remember the number of seat for pax. I know that with more than 29 seats a flight attendant is required. The beginning of each Part describes the applicability. Many large aircraft operate under a "deviation" from part 125. Such would be the case of a corporation owning and operating a Convair 580 with seats for shuttling their own employees. They can operate under 91.
Rhoades is a Part 121 Supplemental Air Carrier for the Convairs. We are Part 135 also, for the DC-3TP and twin Cessnas.

Thanks Jeff !
(Peter de Groot, after reading the above, remarked "..in part135, paragraph 107, is stated 19pax and up requires a flight attendant").

Some examples of operators of "round engines":
Everts Air Alaska is a Part 135 Air Carrier
Everts Air Fuel is a Part 125 Air Operator
Everts Air Cargo is a Part 121 Air Carrier
Brooks Fuel is a Part 91 fuel carrier and a Part 125 Cargo Air Carrier
International Air Response is a Part 137 Operator (the US regulation for aerial firefighting is considered "Agricultural Operations").
See my Links page for links to these companies.

FAA 's Code of Federal Regulations-CFR index

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