Short Version: How does the FAA define the terms "make" and "model" in regulatory documents, particularly in the context of referring to pilot experience in aircraft?
In 14 CFR 135—and doubtless elsewhere in 14 CFR—the FAA occasionally uses the terms "make", "model", or some combination of these, such as "make and model".
Specifically, §135 gives requirements for pilot experience to be eligible for certain operations, such as to operate under "eligible on-demand" rules or to act as PIC.
See, for example, 14 CFR 135.4, "Applicability of rules for eligible on-demand operations":
(3) Pilot operating limitations. If the second in command of a fixed-wing aircraft has fewer than 100 hours of flight time as second in command flying in the aircraft make and model and, if a type rating is required, in the type aircraft being flown, and the pilot in command is not an appropriately qualified check pilot, the pilot in command shall make all takeoffs and landings in any of the following situations: [omitted for brevity]
(4) Crew pairing. Either the pilot in command or the second in command must have at least 75 hours of flight time in that aircraft make or model
See also, 14 CFR 135.105, "Exception to second in command requirement: Approval for use of autopilot system":
No certificate holder may use any person, nor may any person serve, as a pilot in command under this section of an aircraft operated in a commuter operation, as defined in part 119 of this chapter unless that person has at least 100 hours pilot in command flight time in the make and model of aircraft to be flown and has met all other applicable requirements of this part.
See also, 14 CFR 135.244
(a) No certificate holder may use any person, nor may any person serve, as a pilot in command of an aircraft operated in a commuter operation, as defined in part 119 of this chapter unless that person has completed, prior to designation as pilot in command, on that make and basic model aircraft and in that crewmember position, the following operating experience in each make and basic model of aircraft to be flown:
In contrast to the foregoing, the FAA often uses the term "type" to refer to the group of aircraft that the pilot must be experienced or trained on. An example of this would be §135.225 (e), where a pilot is required to have logged 100 hours as pilot in command in that type of airplane.
My question is, what does the FAA mean by these terms, and how should we apply them?
I would typically understand the term "make" to refer to the manufacturer: Cessna.
I would typically understand the term "model" to refer to the basic model, without reference to sub-model designations: 172 (but not 172M vs 172R). However, note where the FAA uses the phrase "make and basic model", to make this idea clear, perhaps in contrast to a separate meaning where the word "basic" is omitted.
Type, in reference to pilot certification, seems clearly to refer to all types encompassed by a type rating designation.
To apply this, would a pilot's time in a Cessna Citation 550 Bravo count toward the time required when operating a Cessna Citation 560 Encore? What about in a Cessna Citation 500 or a Cessna Citation 560 Ultra? All of these fall under the same type rating.
Does the FAA offer some guidance on this, or is there a letter of interpretation perhaps?