TC
you stated......
"
Catastrophic TRF: If the tail gearbox departs flight, the associated change of CofG will almost certainly cause the aircraft to pitch out of control due to the (weight x moment arm) change caused by the removal of “x” Kg of metal at the end of that moment arm. ENDEX..... "
I'm very much with SAS on this one.
The following NTSB report should be mandatory reading.
http://dms.ntsb.gov/aviation/Acciden...2013120000.pdf
It clearly shows that loss of T/R and TRGB (and half the vertical fin in this case) is still controllable!
JJ