MerlinMetro
27th Jun 2004, 06:29
Hi, interested to know if the Metro 3 and its variants are certified to the FAR Part 25 regs. My understanding is that they are Certified to the less stringent SFAR41 (a variant on the FAR 23 reg, to allow certain types to be used for commuter ops).
And if true, does operation with reference to V1 engine failure gurantee performance in as with Part 25 without immediate engine feathering to 400ft???
4dogs
27th Jun 2004, 15:11
MerlinMetro,
First port of call is always the Type Certificate Data Sheet:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/D1F2B5C91B56B3D28525672700558A91
Stay Alive,
Genghis the Engineer
27th Jun 2004, 19:36
Comparing FAR-23 to the TCDS, it looks like a classic case of "design to the limits of the certification code".
Not particularly unusual, quite a few smaller transports (Trislander, PC12 for example) are designed right to the limits of FAR-23. The critical limits are usually MTOW, no.pax and stalling speed.
The reason for doing this is straightforward enough, money - it costs at-least double, probably four times as much to certify an aircraft to FAR-25 as it does to FAR-23. Hence you get so many aeroplanes with exactly 19 pax seats, an MTOW of exactly 12,500lbf, and a stall speed of only just under 61KEAS.
I've no idea about the specifics of the Metro, but in general, this is pretty common practice.
G