I saw that memo this morning just before going flying. It said the 76 was a 'low inertia' head. R22's do teach you something useful then, although I did manage to fall out of the sky in the 76 sim at FSI when I had a double eng failure.
Funny how eng chip warnings could appear only minutes after the last mag plug check. The thing is, as an ex engineer, I know fine well how quickly a high speed rotating part can fail with little or no warning at all. Been a bit close to a few of them over the years!
High speed rotating machinery stores huge amounts of kinetic energy. When one or more rotating components burst, that energy is released. For example, a rotor weighing 272 kg (600 lbs), having a diameter of 76 cm (30 in) and spinning at 14,000 rpm has an energy equivalent of 2.1 x 107 Joules. This is equivalent to the power of some bombs. Even small rotors spinning at high speed can cause catastrophic damage during a burst.