Mirage turbocharged injected engines routinely operate to -30-40C. At that temp main challenge is fuel icing risks but that is more related to the fuel rather than engine itself.
Thanks all. Fascinating stuff. Makes -15C sound a balmy Summer’s day…
I have seen -37C in flight (FL195 near Norwich, UK).
Avgas freezes around -59C but there are possible fuel system issues such as this which happen at much warmer temps since they don’t involve the fuel actually freezing. Avtur freezes at something like -45C (google BA038 and the accident report, for a classic treatment of the subject) but jets benefit from aerodynamic heating of the fuel tanks so they can fly even at -85C OAT although they need to avoid long low power descents afterwards.
The heater is another topic 
A properly set up TB20 one will be ok down to maybe -30C at night, and easily so in daytime (I was wearing shorts on that -37C flight). Some other types are not as good though.
Jet-A freezes at a maximum of -40 and Jet-A1 (used in Europe) at -47 but the bigger problem is water precipitating out of the fuel and blocking filters.
Many jets have oil-fuel heat exchangers (as does mine) so the issue doesn’t arise.
Peter wrote:
there are possible fuel system issues such as this which happen at much warmer temps
Wow, that’s a pretty sobering report (especially as I fly the same type). So ice in the fuel servo is a real problem, and no-one (or very few) knew about using alternate air as a solution, not least the manufacturers?
The POH says use alternate air in all icing conditions, but you get two factors:
The POH says use alternate air in all icing conditions
Understood and duly noted for future ref And yet the report says: “…the Operation Manual (OM) of the PA-28-R200 does not provide instructions for the preventive use of alternate air to avert ice formation in the fuel injector in icing conditions.” A semantic spitting of hairs then perhaps.
Peter wrote:
Some other types are not as good though.
In DA42 it’s hard to stand -20 – the engines simply don’t provide enough heating and insulation is practically non-existing, especially when compared to TB20.
I have a thick woollen jumper, which is so warm it can’t be worn on ‘normal’ winter days. Same applies for a fur hat.
An Irvin-type lambskin flying jacket would keep you really warm but unless you have an open cockpit biplane you’ll just look silly
I once got up very early on a sunny January morning and it was only M05 but I the perspex kept fogging up, inside and out, and even warming the engine for ages the exhaust-exchange cabin heat was useless.
I wonder if Stephan ever solved that problem. I would expect an SR22 (modern type) to be pretty good.
As regards clothing, it’s funny how things have changed over the years. I used to have a ton of woolen pullovers, leather jackets with warm lining, etc. All that stuff went to the charity shops about 15 years ago… I find that modern fleeces are vastly better – as warm as anything else but much more breathable. The drawback is that I look scruffy, but I don’t care
