Originally Posted by
turboshafts
Radial load from the rotor mast is transferred through the upper planet carrier
and onto the planetary gear.
Is it though? I think if you look more closely you may find a bearing locating the 2nd stage carrier in the centre of the 'lid' of the epicyclic transmission module. Or is that only an oil seal? The location however of this bearing is dependent on integrity of the epicyclic casing below it. Have another read of post #1507. It may make more sense now why I was suggesting an additional load path around (from above to below) the epicyclic.
The 1st stage carrier does look to be floating. As jimf671 points out this carries less torque. As far as I am aware, no 1st stage planet has catastrophically failed in flight although AH have found cracks in at least one removed from service according to the G-REDL report.
Also the suspension bars locating the upper mast bearing are unlikely to have contributed in any way to the fatigue crack in the planet gear that propagated to failure. Three bars is determinate and an ideal way of locating something with predictable distribution of loads. On this aircraft they failed as a consequence of gearbox breakup, they were not a cause of it. Once the lower location is lost, no number of bars at the upper bearing will prevent the mast pivoting. The bars can take axial loads only (i.e. in their own axis), normally tensile.