'StartUp' Overspeed
Hmmm.
Starting the engine with the drive belts not-engagaed is a different type of overspeed. The massive torque on the lower driveshaft, which in a sense has not yet been secured by the drive belts will cause a destructive harmonic resonance. Imagine holding a 10 foot long thin peice of bamboo, and spinning it around in your hands....the free end will be all over the place. However, when you engage the clutch, you are secureing the free end, and the resonance is thus dampened. This is why, it is not an overspeed when you go from idle to full when the clutch system is engaged (as in a autorotation power recovery). The point is, this kind of overspeed occurs way before the engine has got to normal operating RPM. Thus, I don't think a govenor can help here.
Disclaimer: Now, I'm not a mechanic and have based that last paragraph on my understanding of the 300CB 'startup' overspeed. The 300CB POH specifically sets paramaters for what is an overspeed or not. I would love someone with more understanding to help out here and confirm whether the case is similar for R22.
I would be most interested to hear what RHC have to say about this.
CL