View Full Version : FAR23 vs FAR 25 for aircraft >5700kg's

1st Jul 2004, 06:22
In relation to the heading is the take off performance for certification identical, ie V speeds and performance with loss of engine and the 400, 1500 ft height segments etc.

1st Jul 2004, 08:01
FAR 23 doesn't even know such things exist ....

If you are looking at the commuter type aircraft which are a bit above 12500, the basic FAR 23 isn't relevant.

.. or have I missed the thrust of your question ?

2nd Jul 2004, 05:52
So what u saying is that if an aircraft, in the case of me Metro liner is certified in acordance with SFAR41, a derivative of FAR 23, then it doesnt have to meet the requirements of V speed scheldule operation, and the segmented takeoff performance like the big jets. ????

Genghis the Engineer
2nd Jul 2004, 08:10
There are a whole series of certification codes for aeroplanes, in order, the main ones are:-

FAR-103: ultralights, single seat, below 115kg empty weight

- Section S, UL2, BFU-95: light aircraft up to 450kg, Vso<35n, max 2 seats.

- JAR-VLA: non-aerobatic light aircraft up to 750kg MTOW, Vso<45kn, max 2 seats.

- JAR-22: gliders up to 750kg MTOW, motorgliders up to 850kg MTOW, Vso<80kph, max 2 seats.

- JAR-23: aerobatic or IMC capable light aircraft, all aircraft between (roughly) 750kg and (roughly) 5,700kg, twins, Vso below 61 kn, max 19 pax seats.

- FAR-23, as JAR-23 but permitting more than 2-engines.

- JAR/FAR-25, anything that doesn't meet any of the above limits.

(These definitions are a bit simplistic, but make the point.) Each time you move up the ladder, the cost and complexity of certifying the aeroplane go up - this is deliberate, since each step marks both an increase in risk to the general public in the event of an accident, and a decrease in survivabilty on-board in the event of an accident.

So each time you step up, a huge raft of areas become more complex - whether it's asymmetric handling, OEI climb performance, gust loadings on the wing.

As a consequence you'll find a great many aeroplanes (of all classes) that are designed right to the limits of the certification standard. That's why so many small twin airliners have exactly 5,700kg MAUW, so many motorgliders have an MTOW of exactly 850kg, so many light aircraft have a stall speed just below 61 knots.

Which is a very complex way of saying, yes.


4th Jul 2004, 03:25
The Metro has an intermediate set of requirements. I have done work on these in the past and have a reasonable library of AFMs etc.... if you post specific questions, I am sure that one of us will be able to confuse the issue a bit for you.

4th Jul 2004, 04:07
FAR23 sets the certification standard for aircraft up to 12,500 lbs MTOW.
Aircraft above 12,500 lbs must meet FAR25
SFAR41 allows aircraft up to 13,500 lb to meets only FAR23.
The Lear 23 for example was designed as an FAR23 aircraft and had an MTOW of 12,500 lb. With an aircraft, crew, passengers and bagage you were at 12,500 before you put in any fuel !!
Hence SFAR 41:O

In UK you can request a category of C.of A. i.e private, cargo passenger etc depending on what you plan to use the aircraft for.
Under FAA the C. of A category is indicated on the TCDS ( Type Certificate Data sheet). Below 12,500 is Normal and above 12,500 is a Transport Category
Thus if you buy your Grannie a B747 for personal use it will be a transport Category C.of A.:D

4th Jul 2004, 06:11
Thanks for that.