FAR 23.841
If certification for operation above 25,000 feet is requested, the airplane must be able to maintain a cabin pressure altitude of not more than 15,000 feet, in the event of any probable failure condition in the pressurization system. During decompression, the cabin altitude may not exceed 15,000 feet for more than 10 seconds and 25,000 feet for any duration.
“Failure condition” = engine failure. That wording means you need a backup. In the case of the Cirrus Jet there isn’t one at this time. This altitude was also lowered from 33,000 ft to 25,000 ft in Amendment 23-49, which is why the TBM has a higher operational ceiling.
I agree with FAA on this – do we want aircrafts to fly around that in the case of a high altitude engine failure (that might most likely be totally survivable), the occupants pass out before they have a chance to land it safely? No, there needs to be a redundant pressurization system. Even if it’s just an emergency one that will cover you for a descent. You can’t rely on oxygen masks, or 10000ft cabin warning lights to bridge that gap as we’ve seen in the TBM930 and Hellas crashes.
Are they allowed to certify unpressurized planes above 25k, and plan on military style oxygen masks instead? Or is that a no no?
That’s strange, as the SF50 has been certified to 28,000 feet, which is more than 25,000 in the rule.
Are you sure that “any probable failure condition in the pressurization system” = engine failure?
loco wrote:
That’s strange, as the SF50 has been certified to 28,000 feet, which is more than 25,000 in the rule.
Are you sure that “any probable failure condition in the pressurization system” = engine failure?
Yes, the rule is about failure in the pressurisation system not engine. Engine failures are dealt with seperately and you must be able to show the aircraft can be descended to a safe altitiude in sufficient time although oxygen changes the effect somewhat.
Would the Garmin Perspective’s automatic descent feature (activated when hypoxia is suspected) help in getting past this certification requirement ?
No, but it is a possible failure scenario. FAA has some statistic rule as to what is ‘probable’ and not, I read somewhere. Apparently, blowing out a window is not probable. But an engine failure is. There are of course numerous other ‘probable’ things that could also happen in regards to that system, like a malfunctioning outflow valve or security valve, or a leaking door seal.
I took a walk the other day and birds were singing “autoland in v2” and “rvsm not sure”. Obviously may not be true, but autoland sounds intriguing. We’ll have to wait and see.
Finally got to fly one! Just a short flight to holding at FL120 and back to land.
The good:
1. Fantastic view. Think Diamond or even better.
2. Flexible seating, easy entry, pilot can be any height.
3. Minumum buttons, knobs, etc. Remaining ones laid out ergonomically.
4. FADEC and other nannies. It won’t lower flaps if you’re too fast, etc.
5. No problems hand flying. No button to switch off YD??. Smooth ride on ground.
The bad:
1. I thought it would be quieter. High pitch whine even gets through A20s. Subjectively, noisier than TBM.
2. Plasticky cabin feeling.
It is very modern and I’m sure it will be a hit, but I would choose the TBM every time. Maybe I’m just used to it.
I see one flying around Poznan (training probably) and one in the vicinity of Bonn. I hope they crank up production…
Friends of mine are now in Duluth doing the type training and then will bring one here. Have to say can’t wait to see it.
