In the TB20GT it is dead easy. The Master switch does not illuminate any outside lights, and the cabin overhead courtesy light connects direct to the battery (and is easy to flip to the “permanently on” position when a rear passenger is getting in or out).
DA42 is similar although it’s not easy to turn on cabin light unintentionally.
I use a shutdown checklist.
If the stall warner is electric, move the vane as you leave. There’ll be a squeel if you’ve left the master on.
Very easy. Once the avionics switch is off, there’s nothing lit up until the low voltage light comes on!
Forgetting it is usually a post fiddling about with something rather than a post flight thing, SLIM (switches, lean, ignition, master) ensures everything’s turned off after flight, but sometimes I forget to do that if I’ve just moved the plane on the ground or flicked the power on to do a radio check then someone’s distracted me. So I’ve only ever flattened the battery once. These days I always make a paranoid final check before putting the cockpit cover on.
This is why some make a habit of never switching off the beacon.
Years ago I flew a plane where someone had installed a switch in the door handle, connected to a buzzer, so it worked both as a door-open warning and a master-not-off warning. A nuisance on hot days, though, where you wanted to taxi with the door open.
I cannot imagine leaving the master switch on is very common cause for depleted batteries. You would at least hear the gyros rotating. Who would walk away from an airplane with the master on except for walk-around?
On the DA40 (and probably DA42) however, the pilot chart light does not come off with the master switch. So it is really easy to leave it on, and the result is predictable. I cannot remember having seen that on any other airplane I have flown. But maybe I have just forgotten.
How long is it safe to leave the master on without the engine running to mess around with the GPS etc? During my training my instructor used to make out like you should almost never have the master on and the engine off.
There is no major difference between gyros spinning down and gyros continuing to run on my aircraft. Also not every aircraft has gyros spinning with the svionics master off.
It has never happened to me but almost happened once…
Aviathor wrote:
You would at least hear the gyros rotating.
Quite a lot of us don’t have electric mechanical gyros any more :-)
