Originally Posted by
Cubdriver
Janitrols are located in the nose and I doubt that one could light off without at least one engine running. But it is an excellent systems question for an exam and I'll check on it. They also have thermocouples to prevent fuel flow to the unit in the absence of exhaust heat.
I know the Janitrol in the C-411 would operate without an engine online (at least until you depleted the battery) and I thought the one in the Aztec would too, but I'm not certain of that one.
Also, it's been many years since I used one, but without fuel to burn to create heat, how could a thermocouple in the exhaust ever sense heat to permit fuel flow? This seems sort of circular (in the chicken or the egg first sense), but I may well be missing something (like I said, it's been a long time). I did think they had an airflow switch which wouldn't permit fuel to be introduced without proper airflow in unit.