That same show highlighted the fact that the NTSB has consistently recommended that the FAA write into Company Flight Manuals that once trim problems were discovered in flight, "to land the aircraft at the nearest suitable airport". That recommendation, at least for the DC-series, has not been acted upon. As an accessory drive it was not considered structural. And most trim problems, like said earlier, lead to a locked up screw which can be an armful but not a structures failure. They mentioned the same jackscrew was used for all the DC-series aircraft, and that the DC-8 had two jackscrews.