dumb Hobbs question


Well-Known Member
In the 172, does the Hobbs meter start running only when the engine starts, or when the master switch is turned on?

So, if I flick the master on to get an IFR clearance while the engine is turned off, am I running up the Hobbs time?
the hobbs runs off the oil pressure if I remember correctly, so if the engine is not running, it doesn't advance.
That is correct....unless the owner changed it around or something. Theres a lot of different ways people rig Hobbs meters, but like Eagle said...Cessnas come from the factory with it hooked to oil pressure.
I've heard that some twins run the hobbs off of the oil pressure in one of the engines, and if you know which one, you can taxi out on the other engine and save a couple bucks. anyone heard of this? Not that I would do it, just curious.