SPS
The reason for the 75% mag check is, or rather was clutch leaf springs/micro switches. (As I mentioned before and prob not anything to do with the fan)
After FAA appoval of 75% mag checks (13OCT00) they had sorted the spring thing.
I agree with you on the 7% 2sec prob.
Best to do a mag check at 104% and pulling power (low hover) - seriously not advisable.
Doing a mag check at low power/rpm is hardly noticeable so therefore 75%erpm 4% 2secs may be closer to the mark.
___
O-o
"`