Sorry for late follow up as such, some interesting comments, much appreciated. In the company aircraft we lease, I've had a "F/W Chip" light come on. Landed and student used his all singing and dancing "I" phone thingimy (I'm a total pre computer ager, when I joined the Air Force the most advanced piece of office kit at 17 Sqn was a hand cranked copier...) to send a photo to the blackhanders of some very fine metal schwarf on the F/W unit magnetic plug. Was told looks ok, good to continue. If it came on again however within 30 min or so, would have insisted they come and have a look. Yes the incident aircraft discussed earlier had stood for a while, but it had flown a number of auto's before the incident, and somehow water had contaminated the free wheel unit possibly through condensation (Canada - winter). I agree aircraft procedure does not call for throttle close check N2 split, but when I shut down, I do always snap the throttle closed to idle to watch the rate of N1 decay, but again that is to check for turbine rub. Moving the rotor during pre flight is good, always do it to check for any strange noises from engine (t-rub) and transmission and drives, but not sure about watching the power N2 turbines...as far as I know you can't see them, even looking down the exhausts? I still think the sieve is a better option then the restrictor in the F/W oil system. Basically it is a bit worrying that if it does go wrong, it is pretty catastrophic. But then again, that is the nature of the beast, I was discussing loss of the tail rotor emergency procedures with students, but didn't have the heart to tell them that the loss or partial loss/failure of a T/R blade would probably cause such bad imbalance that it would probably throw the tail rotor gearbox, leading to a massive CofG forward shift, making the loss of tail rotor the least of your problems...I think I will go off to the fridge to get a beer.
