In every complex aircraft I've been in, there is a gear warning horn.
Most of them (Cessna) are set to sound when the manifold or RPM drops
beyond a certain point. Makes certain manuovers a bit noisy at
altitude.

And I've heard of an "accidental" gear up landing involving a part 12*
carrier!

And then there is the goofy light problem. If you get two greens, now
what do you do?

I was told, if possible, pull one of the lights that is working and put
it in the one that isn't lit and see if it lights (this is for
locations where no one is on the ground to tell you if you have three
down -- but how would they know it isn't locked?).
Later,
Steve.T
PP ASEL/Instrument