Originally Posted by
nitefltguy
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.
One human factors lecturer used this accident to show how we accumulate data to show we can do things safely. As I remember, the original inspection of the jackscrew was done at 300hrs and by the time Alaska went into the water, that inspection cycle had increased to nearly
3000 hours. Also, the jackscrew had been inspected and was near limits but was still WITHIN limits posing the problem of when do you change out parts.
The inspection was also problematic in that lubrication cannisters, once in the gun, were difficult to identify so it was possible to use the wrong lubricant. Also how it was to be applied, how much and where was fuzzy.
This was all used to show that EVERYONE was involved... the regulating authorities, mechanics, airline, OEM.. everyone said it was safe to continue and had the data to show it could be done. Like Challenger and Columbia.
Yes, the DC-8 had two jackscrews but it was decided the -9 could operate with one much like the 727 had two yaw dampers but you could dispatch the 737 with NO yaw damper so it got only one.
Finally, I have always been taught with a flight control problem you remain in that config is at all possible. The crew had lost control once and regained control before continuing to troubleshoot and losing control the second time.