Updated: May 29, 2019
Helicopter main rotor blades are designed to "cone" up in flight. The blades are held rigid by the centrifugal force imposed with the proper RPM (rotations per minute).
The manufacturer sets the operating rpm and max gross weight with the main rotor blades included in this consideration.
If you overload the helicopter or operate at lower than recommended RPM, you could damage the blades due to over coning.
If the RPM is allowed to drop to the point of catastrophic blade stall, it is possible for the rotor blades to fold before the inevitable crash. If rotor RPM has been allowed to drop to that point, the folding will not change the outcome.
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