Originally Posted by Chris Scott 7th Apr 2011 05:55 Post #3143
The door underneath it is light and flimsy.
Not to put too fine a point on this aspect of the discussion...
Yes, agree with your comments. Further to your point in your response to BOAC, (who, I should acknowledge, has previously mentioned the notion that the gear may have free-fallen slowly, after impact, and during the slow descent to the bottom)...
The MLG doors are made from Carbon-Fiber Reinforced-Plastic (CFRP) with a NOMEX honeycomb core. The belly-fairings are similarly constructed,(the cabin material is the same NOMEX honeycomb structure but with a fibreglass surfaces and aluminum extruded edges/fastenings.) So while light and strong, they are indeed "flimsy" in the sense that direct, high-impact forces would break the material as we have seen in the recovered wreckage. IOW, this material will not "bend and conform" to the shape of the gear and so impede a free-fall, but would likely shatter, and provide no resistance whatsoever to the massively-heavy MLG structure. That the uplocks would break at impact has already been discussed.
Again, when the MLG actually free-fell is immaterial - it did, and it, and its dressings have remained attached to the rear spar and support structure. I think it is more important to rule-in/rule-out the crew extending the gear. It is a debate until the recorders tell us.
I mentioned the THS (
#3129) not in relation to the Perpignan accident (AoA problem) but because I don't recall if/where in the three major AF447 threads, the failures of ADIRUs 1, 2 & 3, which provide input to the FCPCs which control the THS signals, have been discussed.
The aircraft went from M0.82 (or turb penetration speed of M0.78) to about M0.60/198kts (roughly the stall speed under the circumstances). I've tried that in an A330 simulator and it takes long time just to lose 80 to 90 kts in level flight with engines set to IDLE, (not suggesting that engine thrust was idle for AF447, I'm just describing the "loss of speed" experiment). So something else intervened to advance the loss of speed and approach to stall. What, and why?
There is always a causal path to a loss of control whether it resides primarily in human factors, (the known ones such as rule-breaking, distraction, overwhelmed, competence etc), or resides in technical/system causes or, (more likely) a blend of the two. As many have pointed out over the length of these threads, these have always been the primary questions.
PJ2