europaxs wrote:
I don’t know where, but I believe it was in this forum, that a Columbia 400 owner complained about this system not producing enough heat during prolonged descends from the flightlevels.
The Columbia (the Cessna 400 version at least) takes the heating from the intercooler. It works really well, but only if you keep the turbo working hard, so prolonged holds etc. are best done with reasonable high power settings. The advantage is that it is CO safe.
There is a mod to take the heat from the linkage between the two turbos, but I am not sure it is worth the effort.
AdamFrisch wrote:
I was always terrified of running the Janitrol in mine, so more times than not I was freezing my n*ts off. Something about the Janitrol, open flames, gasoline etc in the tail (on my last two planes) that really freak me out. I mean really.
Looking at the NTSB data to that subject, there are a few incidents where Janitrol heaters have indeed malfunctioned in a fatal way,but they are very few indeed and I think that most of those issues were addressed in AD’s.
There is one fatal accident where the Janitrol Heater was labled inop and used anyhow.
So the whole NTSB Database has exactly ONE fatal accident because of the Janitrol heater and 2 ground fires.
Seeing how many of those things are in use, I would not think that this is any base for not using them if they are in airworthy condition and work. What I have heard though is that they often enough do not work in the first place, but that is an inconvenience, not dangerous per se.
FL270 in our C340 between Goose and Narsarsuaq. We still had 800fpm with RAM VII engines. There was a lot of frost on the windows and thank heavens for the Janitrol. In less extreme conditions you can use the turbo bleed air to take the chill off, but if you want a blast of positive warmth you need to burn some gasoline.
mmgreve wrote:
The Columbia (the Cessna 400 version at least) takes the heating from the intercooler.
Well, not exactly from the intercooler since that would defeat the purpose.
The Columbia 400 /TTx uses the warm compressed air coming off the turbo compressor, just before it enters the intercooler, and diverts it to the cabin for heating.
As stated, for this to work, the turbo needs to be “working” AND you need a very tight leak-free cabin.
IIRC, the 400 owner/pilot that complained about the heating also had an issue with the pneumatic door seal.
Mooney_Driver wrote:
What I have heard though is that they often enough do not work in the first place, but that is an inconvenience, not dangerous per se.
That’s because they have a couple of “fail safe” devices built in, so if the operating parameters are not met (think over-heat, lack of air, etc.) then they shut down, hence the rather frequent “inops”
Michael wrote:
[Columbia 400]… had an issue with the pneumatic door seal.
Given a sample of three, I have yet so see one that did not have damage to the door seal caused by the door locking mechanism and an a clumsy pilot/mechanic/handler, and/or a patch at that particular location…
On the Columbia 400 the locking mechanism does not damage the pneumatic seal which is on the door itself. It damages the rain seal which is on the door frame. On the other hand the pneumatic door seal can be damaged by something caught between the door and the frame, for example a seat belt buckle.
My understanding is that at 25,000 ft the partial pressure of O2 in your lungs is the same as in the cabin. Therefore, you need a positive pressure of O2 (“pressure breathing”) in order to be able to breathe. In my military days the cabin was pressurised to “half plus two” i.e. at 48,000 ft the cabin was at 26,000 ft which is about when pressure breathing started automatically, so I think it makes sense.
The celing in my A36TN is now 25,000 ft. I haven’t been that high yet but at 24,000 on air test I was still climbing at 400 fpm, so I’m sure the engine would take me way above 25,000 ft.
You donot need pressure breathing at 25.000 ft, fortunately. Pressure breathing is a very strange experience, as is listening to R/T from someone who is doing it, if they are not trained and used to doing it. Inhaling pure oxygen, I agree you only need pressure breathing at altitudes where the absolute total air pressure is lower than the partial oxygen pressure at sea level, but that happens at a higher altitude than 25.000 – it is closer to 40.000 ft as I remember.
