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Locking switches--both positions, or just "on"?

rmartingt

Well Known Member
Musing over some switch philosophy while heavy into panel planning...

Let's say you have some critical switches (e.g. fuel pumps, ignition coils, etc. for an electrically-dependent engine), or even just some switches that would be mighty inconvenient to accidentally turn off. To me, it is obvious that you would want a locking feature to prevent those switches from being bumped accidentally and shutting off power. But should it also be required to turn them on?

Here's my thinking... my master switches and main engine power switches will be locking both ways--you'd have to unlock them to turn them on or off, thus preventing accidental shutoff in flight, or accidental activation on the ground.

For some of the other engine-related switches, like the fuel pumps and maybe the ignition coils, I'm considering using switches that lock into the on position only--you have to pull/unlock them to shut them down, but they can be activated simply by pressing them up. My thinking is that if I put the engine-related switches all in a row, including the primary/backup ECU select switch, then part of the engine failure checklist/memory item list would be to simply push all those switches up. On/Up would be the "safe" direction for in flight, and on the ground it wouldn't matter (the engine power switches should be off on the ground and they lock both ways).

Am I overthinking this, or is it reasonable to make turning these things on easy, and turning them off hard?
 
Personally I think there is a lot of over-kill here. Just place the switches where they are not likely to be "bumped" during flight.

I placed my Master and Avionics Master to the far left away from other switches. My Ignition switches are on the sub-panel with the throttle and mixture controls.
Airframe related switches are located across the top of the panel. Been this way for over 25 years and never regretted anything.

Of course it's your airplane and you are the final authority. You need to do what you are comfortable with.
 
I’m with Mel on this - too many lever-lock switches can make activation/deactivation difficult. (Not to mention, they are expensive!). A step in between unprotected toggles and lever-locks is to use switch guards - they really help in keeping things from being bumped.

I do use some lever locks - mostly for things like an avionics master that turns on all the fancy navigation stuff. Primarily this is to make me think before turning them off because you can lose a lot fo programming when they go dark and you have to start loading the flight plan over....

Personal preference, but I make limited use of them.

Paul
 
I am with Mel on this, Location.... location.

The only switch that needs guarded is the EJECTION switch.....:eek:
 
What I did...

I have Robert Paisley's EFII system, electrically dependent. On this system, the only switches that are truly critical not to be turned off are the master and the two ignition coil switches. In my setup, the master is keyed and the two coil switches are locked in the on position. The fuel pump switch just selects between the primary pump and the identical backup pump and the engine doesn't care which pump is delivering the fuel. The ECU switch just controls which ECU is operating the fuel injectors and again, the engine doesn't care about that either. The emergency power switch is only critical if the bus fails and the engine doesn't care if this is switched on either.
 
Lock both directions for the stuff I don't want to inadvertently turn on or off.
One way locks are to easy to bump on by accident.

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