Originally Posted by
Lonewolf_50
Pablo, are you referring to the upper bearing where the mast comes through the top of the housing? Unfamiliar with this aircraft, but I think I understand that there are oil jets that keep lube coming to that bearing. If the lube doesn't get there, how does a rising temperature get detected? (I think I see your point on an impending bearing failure being picked up by a HUMS sensor).
On the 225 the MRH shaft is supported in the lift housing by 2 taper roller bearings. The bearings are lubricated by internal drillings in the lift housing and MGB Flared housing.
All should become a lot clearer tomorrow.