Selfloading said:
Dunno, is it not possible the the fairing did not come away in one piece but broke up, and in doing so punctured the pressure hull?
Naaaaa. Had lots of fairings come off. They're plastic, composite, honeycombe, or thin sheetmetal affairs (or combinations.) Think flimsy. Think light. Think designed by Mr boeing not to be anchored into important structure without the fastner hardware designed to yield or strip free before it would be able to rip apart something as stout as a Frame or longitudinal stringer or spar.
What most SLF don't realize is that Goldfinger and Airport 77 are fiction. A small hole in the skin (if it doesn't break a crossbeam) probably isn't going to cause a rapid decompression. Conversely the 747 is not a boat; it is not water tight. In it's normal state, it is absolutely full of holes, leaks, seals hissing.....
Stick your hand down near a galley door. Chances are you'll feel it. Cold from the venturi effect of air escaping.
Sure, if it came loose, that fairing would flap around and maybe cause some little holes in the skin or screw up something else down stream when it disintegrated or possibly even go through an engine if you're real unlucky, but I can't see it causing that kind of damage.
IMHO, this is either a structural failure of the pressure vessel which took with it everything fastened to either side of the wall (O2 tanks and fairing)
- OR -
a structural failure of an oxygen tank that destroyed the integrity of the frame latticework.
Always suspect problems when engineers realize that the area has been previously repaired (as in this case.)
I give you as a case study, JAL Flight 123. The engineer who approved the repair committed suicide when it became obvious it was designed improperly.
Japan Airlines Flight 123 - Wikipedia, the free encyclopedia
Cause
The official cause of the crash according to the report published by the Japanese Aircraft and Railway Accidents Investigation Commission is as follows:
The aircraft was involved in a tailstrike incident at Osaka International Airport on June 2, 1978, which damaged the aircraft's rear pressure bulkhead.
The subsequent repair performed by the engineers was flawed. Boeing's procedures called for a doubler plate with two rows of rivets to cover up the damaged bulkhead, but the engineers fixing the aircraft used two doubler plates with only one row of rivets. This reduced the part's resistance to metal fatigue by 70%. According to the FAA, the one "doubler plate" which was specified for the job, (the FAA calls it a "splice plate" - essentially a patch), was cut into two pieces parallel to the stress crack it was intended to reinforce, "to make it fit".[10] This negated the effectiveness of one of the two rows of rivets. During the investigation Boeing calculated that this incorrect installation would fail after approximately 10,000 pressurizations; the aircraft accomplished 12,319 take-offs between the installation of the new plate and the final accident.
When the bulkhead gave way, the resulting explosive decompression ruptured the lines of all four hydraulic systems. With the aircraft's control surfaces disabled, the aircraft became uncontrollable.
[edit]Aftermath
The Japanese public's confidence in Japan Airlines took a dramatic downturn in the wake of the disaster, with passenger numbers on domestic routes dropping by one-third. Rumours persisted that Boeing had admitted fault to cover up shortcomings in the airline's inspection procedures and thus protect the reputation of a major customer.[4] In the months after the crash, domestic traffic decreased by as much as 25%. In 1986, for the first time in one decade, fewer passengers boarded JAL's overseas flights during New Years than the previous year.[11]
Without admitting liability, JAL paid 780 million yen to the victims' relatives in the form of "condolence money". Its president, Yasumoto Takagi, resigned, while a maintenance manager working for the company at Haneda committed suicide to "apologize" for the accident.[4]
Also there's this:
Safety Promotion Center - Wikipedia, the free encyclopedia
Section 41 and section 43 mods addressed known areas of weakness in the 747 design. The drawing supplied to us earlier in this thread is said by the poster to come from section 42.
These are all just my opinions; I am not an expert.
pac