Other than this one copa is one of the very few forums worth visiting these days.
Peter wrote:
Interestingly, in the TB20, alt air closes off the air path from the air filter. I wonder why they did that?
Ice that forms behind the filter can detach itself in blocks and obstruct the alt air or damage the engine, I would guess.
Peter I will have to ask the guys on the CPA forum who fly 210s. There is a lot of experienced pilots on there if there is an issue it will come up.
CPA is a great source of maintenance information plus parts as well as experience with flying. It has saved me thousands of $ a year. Never been to the COPA or Beech site since I have never owned one. Although I have heard that Beech is wellworth it as well.
What are they saying about it? It would be a contribution to flight safety if the pilots who read EuroGA (currently ~800/day) can learn from it.
Nothing much because there’s no data – most analysis relies on having a download from the aircraft. The thread has gone quiet for now.
If I had to criticise, it’s a bit of a cultural thing. Everyone is just too polite on there – it feels like Sunday School sometimes.
I really like that part the best. Permanent aggression drove me away from some European forums. And I don’t mean “tough discussions” .. I actually like those. No, but stupid, mean aggression and jealousy. You knwo how often I had to read “you think you are something better just becasue you have a Cirrus”. Not only do i find commects like that stupid, I find them boring too. With COPA i never had that problem, after all everyone has a Cirrus there – or a PC-12 or TBM :-)
If the “alternate air door” opened up in warmer air – so I presume during descent – could it not be that it actually functioned as advertised and opened when icing occured in “warmer” temps than at FL230?
If the wastegate controller failed, would that bring manifold pressure to around 11 at that altitude hence rendering the engine seemingly impervious to throttle changes?
Flyer59 wrote:
Everyone is just too polite on there – it feels like Sunday School sometimes.
It’s the same on the “Vans Airforce”, more like a tea party for (really) old “distinguished” men. But there are so many there with tons of knowledge and experience, so it’s a technical recourse like no other. At the same time, such product specific forums tends to be void of healthy criticism of the product itself, or the company/designer.
Anyway, that Cirrus icing up could be another problem altogether. It could have “iced up” after the engine stopped for some other reason.
Flyer59 wrote:
Permanent aggression drove me away from some European forums
Funny, I don’t know any European forums except this one 
“The fact that the alternate air door ices up is very revealing of a big problem. It means
supercooled water droplets pass through the air filter (hardly surprising)
the air passing by the alternate air door has been warmed up sufficiently to be in the “danger” band of 0 to say -10C even when flying in -15C (TB20) or -25C (SR22T)
If an SR22T iced up its alternate air door while TKS was running suggests that the NACA inlets don’t get the TKS going in."
Peter even if TKS were to get in through the NACA inlets it wouldn’t help as the (heated) alternate air box and door are upstream of the air filters on the SR22T. TKS would have to pass through the filter and do a 180 turn and flow upwards to the box… unlikely. For the same reason it’s quite unlikely to have compression heating on the alternate air box and door. And any supercooled droplets getting through the filter would end straight in the compressor as well, not in the air box.
As a graphical illustration to the above – see http://servicecenters.cirrusdesign.com/pdf/SR22T_Technical_Presentation.pdf
Page eight there is a very good photo showing the two filter canisters, with the outside air port on the outer side and the alternate air port on the inner side, with the scat tubes connected to the alternate box below the prop shaft. Close-up photo of the filter canister on page 20.
I think in this configuration a stuck wastegate / controller failure is more likely than both filters getting iced up and the alternate airbox sticking closed…
