[Homer Bell]

It could be rocking on the shaft, not the bearing failing, just not tight on the shaft. If that’s the case you might not see any heat buildup. Trouble with that is , the shaft is probably being worn down and might eventually fail. Most bearings should be Lock Tited on installation to prevent this from happening. Long driveshafts and harmonics can be an engineering nightmare. Look at the way the tail drive shaft is mounted in the R22, pretty interesting design. But over-speeding the rotor system in these ships with drive shafts is a big no no, don’t do that. However in a RW with belts, 120%, no harm done, very forgiving.