Greek Apache Helicopter crashes into sea.

[JohnDixson]

SAS, I believe that LRP has the correct picture re the UH-1C and subsequent Bell rotors that incorporated pitch/cone coupling by design.

This particular AH-64 video reminds of several others:
1. BO-105 accident with Seifried Hoffman flying, in New Jersey, I believe.
2. Last year's NH-90 crash into a lake.
3. The S-67 accident practicing the demonstration routine at Farnborough 1974.
4. A similar UH-60 "incident" flown by a US Army crew and I can't remember the time, but it was filmed and SA got the blades back. An "almost " version of the first three. The aircraft is seen doing a vertical type manuever and the pullout is at first obscured from the camera by a tree line, and then, just when you'd expect to see the smoke, the ship reappears.

The issues in 3 and 4 were looked into in detail, and I'm suggesting that the first two are similar. It is altogether both possible, and easy, when throwing a helicopter around close to the ground, to put the machine into a position where the application of maximum power/collective and appropriate cyclic input is insufficient to sufficiently change the flight path of the machine given the altitude remaining. A related consideration is that there is sufficient collective range in most ( if not all ) machines at the speeds noted in these examples ( and the Apache accident as well ) such that application of full collective will demand more than the power available, resulting in rotor droop. With rotor lift being a function of the velocity squared, this can really aggravate an already bad situation.

In the case of the S-67, the video showed extremely high flapping/cloning prior to impact. In the case of the Army UH-60, each of the rotor blades had wrinkled trailing edges, the result of aft damper stop contact. Damper lag angle in an articulated head is a pretty much linear function with power: higher power=increased lag angle.

There may be other factors involved in this Apache accident, rendering the above thoughts irrelevant. Stuff happens: I recall the story of an accident that occurred with a UH-2 Kaman machine where a very high speed crash was finally attributed to one of the pilots heels getting sandwiched into the base of the cyclic.