Difference between commuter and transport categories

[Chuck_YeagerBomb]

G'day folks been trying to track down a clear definition for the differences between these categories but to no avail... and what the hell is a SFAR 41 aeroplane anywho?

Cheers

[Lefthanded_Rock_Thrower]

You need to go to the far superior FAR's ( the FAA legislation ), they have a website, you can chase down the certification info there. Enjoy........

[Tinstaafl]

Here's my understanding. Bear in mind I didn't grow up in the US system so there's quite probably errors. Even so I think I have the general idea.

Broadly, most civil aircraft are certified (jeez, I loathe the word 'certificated' which seems to have become the norm. Dunno why, but I do) under one of two US sets of regulations - Federal Aviation Regulation 23 (FAR 23) or Federal Aviation Regulation 25 (FAR 25). These, in turn are a subset of Part 14 of the USA Code of Federal Regulations ie the overarching set of US Fed. Regs. from which all the others gain their authority.

FAR25 deals with Transport Category. This set of rules specifies with great detail what requirements must be met for an aircraft to be certified to comply with these rules. A general rule of thumb is that FAR25 aircraft must be able to have sufficient performance, and constrain their operations at all stages of flight, to either reject the take off or continue flight to land at a safe airport. Additionally, there are requirements about redundancy to systems & procedures to prevent any forseeable single point failure leading to a significant reduction in safety.

Pretty much any airliner is a FAR25 aircraft.

FAR 23 specifies the requirements for an aircraft to be certified under its set of specifications. Generally aircraft certified under this part do not have to meet the same level of performance or redundancy that FAR25 aircraft must meet. Most general aviation aircraft from pistons to turboprops fall under this Part.

However, within this Part are subsections, one of which refers to commuter category aircraft. This subsection tries to give some semblence of FAR25 aircraft performance & redundancy, but without having to go through the entire FAR25 rigamarole. It's intended to cover aircraft that were never designed to be FAR 25 type aircraft but are used similarly ie Regular Public Transport.

This isn't meant to imply that getting an aircraft design certified under FAR 23 is simple or easy. It's not, but in general meeting FAR 23 requirements is less onerous. For example, a multi-engine aircraft has no requirement to have asymmetric climb performance except in an aerodymically clean configuration at maximum continuous power.

Special FAR 41 (no longer current) was a special FAR (hmmm....what gave that away?) that allowed certain FAR 23 types to gain a supplemental type certificate that went a little way towards FAR 25 safety. It's no longer current and, I believe, has become the FAR23 (Commuter) requirements.

[mjbow2]

The simple version goes something like this.

Part 23 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=66dd96ba24f9921c6441f7c05df69d55&rgn=div5&view=text&node=14:1.0.1.3.10&idno=14) deals with the certification/performance requirements of all non turbojet aircraft less than 12,500lbs (5700kg) in the Normal, Utility, Acrobatic and Commuter categories.

Once upon a time all non jet aircraft <10 seats were certified under Part 23 which was segmented only by the Normal, Utility and Acrobatic categories.

SFAR 41C was designed to add a 'commuter category' for aircraft like the King Air B200 and Swearingen Merlin with the ability to grow and exceed the 12,500lb limit set out by Part 23, but which mandated a higher level of safety (ie performance).

SFAR 41C was valid for only 10 years which included a 'sunset clause' when FAR Part 23 commuter category superseded it.

SFAR 41C aircraft include Beech King Air 300 1900A-B and C models (oversized King Airs) and the Swearingen/Fairchild Metro 1, 2 etc ( Merlins on steroids). The Metro 23 was certified under the new FAR Part 23 (commuter category) as was the Beech Super King Air 350 and 1900 D model.

The commuter category of Part 23 allows aircraft with between 10 and 19 seats and/or >12,500 lbs max take off weight to be certified under this part rather than the more onerous Part 25. From memory the maximum certificated weight for a commuter category is 19,000 lbs. (Some one may wish to check that)

Part 25 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=66dd96ba24f9921c6441f7c05df69d55&rgn=div5&view=text&node=14:1.0.1.3.11&idno=14) deals with certification/performance of aircraft greater than 19 seats. And those aircraft that are turbojet powered. There is no lower weight limit for Part 25 aircraft.

It has been a while so someone may wish to correct any misleading information in the above.

[tcasblue]

Part 25 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=66dd96ba24f9921c6441f7c05df69d55&rgn=div5&view=text&node=14:1.0.1.3.11&idno=14) deals with certification/performance of aircraft greater than 19 seats. And those aircraft that are turbojet powered. There is no lower weight limit for Part 25 aircraft.

It has been a while so someone may wish to correct any misleading information in the above.

Exemptions for jets are now available...

https://dms.ntsb.gov/public/59500-59999/59774/602495.pdf