Has anyone done a comparison of post engine shutdown rotor run down times against another example of the type? The gearbox change may be significant in that it's internal drag may be higher than it should be.
I sometimes shut off the engines and observe the rotor rundown from the cockpit with my headset off, without using the rotor brake. Not required by the manufacturer but I feel it's worth doing on occasions.
Another clue is at what N1 the rotors start turning on startup. However, I feel this is less reliable because the oil isn't up to working temperature.q