I know in the CF6-6 and -50 engines LPT Coupling nut was at the end of the LPT ,,,,the hot end of the engine ,,,stays nice and dry , The Genx is at the front of the engine ,its always more cold and moist (visible during ground runs ). This means it cycles cold to ambient numerous times and creates moisture each time.
Partially true. More to the point, the CF6 family (-80s too) have splines w/ coupling nut at the AFT AND FWD ends.of the FMS.
Thus the GEnx-1B thread cracking issue seems to be more related to its unique chemistry/metallurgy, and NOT to its non-unique cold-end location.
