A_Pommie.
I take your point about certification but a HC based system using, say Propane (R290) is going to have around 250g due to density differences compared to a HFC system. If you have a leak then you won't get more than a 50% discharge so you are now down to 125g (about 2 cigarette lighters equivalent) which will require an auto ignition temperature of more than 420 C to ignite.
Significantly less than the fuel you are carrying. And not a major hazard in the greater scheme of things.
My point about using a HC was that they are more efficient and can be designed to be smaller in many cases, which is why I asked the question. It just seems to me that with some of the modern Diesel engines being developed it would be nice if we could have A/C in a plane as well.
