Single load path
Every pound of the aircraft hangs from the main rotor system. Components like the "Jesus nut" (main rotor retaining nut) have no redundancy — which is why rotorcraft maintenance uses strict life-limited parts, replaced on schedule regardless of condition.
Autorotation: the built-in parachute
If the engine fails, the rotor keeps spinning like a maple seed as air flows up through it. Pilots trade altitude for rotor energy, then flare to cushion touchdown. Toggle it above: descent ~1,700 ft/min, RPM maintained by airflow, survivable when flown correctly — it's practiced in every helicopter license.
The over-water problem
Maritime ops stack risks: no visual horizon at night (spatial disorientation), salt corrosion, a moving landing pad, and rotor downwash spray. Degraded visual environments are a leading factor in over-water accidents across military and civilian fleets alike.
The deadly corners
The height–velocity diagram ("dead man's curve") maps combinations of low altitude and low airspeed where autorotation can't fully develop. Naval hovering ops — winching, deck approaches — live near those corners by mission necessity, not by carelessness.
"Why do helicopters keep crashing?" — the sober answer
Militaries fly rotorcraft in exactly the regimes civil aviation avoids: low altitude, night, over water, in formation, on tight timelines. Mishap investigations (each U.S. Navy accident gets a formal one) most often cite a chain: environment + human factors + mechanical contribution, rarely one cause. Fleet-wide, U.S. naval aviation's severe ("Class A") mishap rate is on the order of roughly 1 per 100,000 flight hours — far safer than decades past, but each loss is a crew, which is why every crash drives procedure, training, and engineering changes. Rather than a mystery, it's a hard operating envelope being flown at industrial scale.