I've just started my multy commercial training with Beechcraft 76 Duchess. While im going thru the fuel system i found on the system schematic that in the priming pipe between auxiliary pump and primer there is an "primer solenoid", as well as in pipe going to the heater is "heater solenoid".
In the system description of engine priming: The battery master and the aux fuel pump (l or R) switches must be turned on prior to activating the fuel priming system. The push to prime switch may be actuated in either the both or start position. Pushing in on the magneto/start switch activates a solenoid, located behind the firewall in each nacelle, and supplies fuel directly into the no. 1 2 and 4 cylinders for engine priming.
The questions are:
What are those solenoids for? My instructor said that the main purpose of solenoids is to drive the fuel from the tank into the cylinders (or to heater in cabin heating system). But im quite unsure with his answer, because it seems to me not logical. My guess is that that solenoids is like a shutoff valve. They are not driving fuel itself (it must be done by pump), but opening valve in pipe so fuel can go to cylinders when priming activated, or heater system switched on.
Could you, guys, who familiar with what are solenoids, what are they for in fuel system for, explain me this. And if you have pictures or schematics of how that kind of solenoids looks like to share a link.
Thank you very much!