Such a waste of a good helicopter. If you're able to watch the slow motion footage you'll see one of the aft blades break its blade damper grip. That is the cause of the aft pylon seperating from the fuselage. Take a closer look though at how the engineers attached the helicopter to the pad. No one in their right mind would disable the oleo strut function of an articulated rotor system helicopter. So this is the end result. Helicopter goes into ground resonance, aft blade lead/lags beyond perameters, aft blade damper grip fails, aft blade goes out of rotation, aft blade contacts forward blade, and aft pylon fails from imbalance in centrifugal force.
Each blade is 350#
Rotor 225 rpm
60' rotor diameter
(Blade tip rotating at appx 8 mpm or 480 mph or 704 fps)
A Break down in repair.
Blade $210,000 ea: need 6 ea
Aft Transmisison $780,000 ea: 1 ea
Enginge 1,000,000 ea: 2 ea
Engine Transmission appx $280,000 ea: 2 ea
Aft Vertical Shaft appx $160,000 ea: 1 ea
Aft Pylon appx $????? expensive
engine drive shafts, $???: 2 ea
Hydraulics repairs, airframe repairs, drive shafts 1-9 replacements, I think they have to replace both heads, and the combining and forward transmissions as well. I would guess about 8-10 million easy in damage, and this is mostly the big stuff. But it doesn't take into effect the cost of pride and loss of major cool points.