The scene…Preflight of widebody (Old Pilot showing New Pilot the ancient art of survival which starts with a thorough and knowledgeable walkaround).
OP This is the main landing gear.
NP Wow! (sonofabitch this is a big muttha sukka!)
OP We must check that the gear pin is removed before flight. Show me where the gear pin goes.
NP (Easy question, I am think that I am getting a greasy grip on this flying business). In this hole Captain!
OP Good lad! Now tell me how the gear is extended young fella!
NP You select MLG handle down… (is this guy nuts?)
OP And how does that actuate the gear to extend?
NP Arrrrr….the electro mechanical lever doodad uses hydraulics to power the gear down?
OP Very good!
NP (Thank goodness…This guy is out to lunch…and I am gonna have to fly with him all day?).
OP Now, I think you will notice that the hydraulics are now completely un-powered, so how is the gear being prevented from folding up and crushing us to death as we do our walkaround?
NP (Holy crap! This is bad! Thinking very quickly…) Ahmm… there is some over centre doodad that creates some sort of geometric lock?
OP Very good lad, and here it is that lock just where you showed me the gear pin hole is located. Now can you tell me what is holding this over centre lock in position?
NP (Straining eyes and imaginative resources…) Might it be these little springs sir?
OP (This lad is going to be a great aviator!) I shouldn’t have to lead you around by the nose. You are going to have to work a lot harder if you want to continue a career in aviation.