1975. I was a young L/cpl in an 81mm mortar platoon. Flew off a LSD (landing ship;Dock- not the other one) off the coast of Spain. Ch-46, the Marine version of the Chinook helicopter. Going to spend about a week in the field, no biggy, usual grunt stuff. Aircraft hummin' along nicely as Ch-46's go, probably at about 5000 feet guesstimate. Cruisin' along, remember weapons pointing downward, everyone just sorta lookin' at each other, blah, blah blah. No headsets for us, no internal communication, we're just grunts along for the ride. Power gone. Engines silent. Drop like a stone... CH-46 has the glide ratio of a safe. We just look at each other... I reckon' it to be a macho-jarhead thing, I was scared beyond explanation. About 10 seconds (estimate) prior to impact, on come the engines, aircraft vibrates to the point that all blurs in my vision, noise barely endurable, aircraft suddenly slows rate of descent literally while able to see out the opposite window landscape. This is how I was introduced to the concept of auto-rotation, a methodology employed for "rapid vertical envelopment" to avoid ground-fire, etc. Woulda been kinda nice for the wing-wipers to let us know, IMHO. Scared of flying? Every single (hundreds, and hundreds) time, in every kind of aircraft, and STILL refuse to let anyone know... We're (jarheads) as dumb as we look.