NTSB AAR 92/02 text and photo above for UAL 811
Comment: If you go to http://www.corazon.com/811page35analydoor.html
or view above you will see the forward cargo door of UAL 811.
The UAL 811 door has a rupture at aft mid span latch. The aft midspan latch was damaged while the forward one was not. What is seen is a small rupture at aft midspan latch of door that led to door departing in two pieces and then slamming upwards and transferring paint to skin above.
What is seen in TWA 800 reconstruction photo TWA800hullrupture.html is large rupture of fuselage at forward cargo door at aft midspan latch. The large rupture allowed the bottom latches to stay latched while the top part of the door slammed upwards and transferred red paint from the door to the fuselage above.
If unable to positively identify all the latches from TWA 800, in particular the aft midspan latch, then the door rupture at aft midspan latch can not be ruled out and must be investigated further.
Aft midspan latch area of forward cargo door is six inch square and is shown to be damaged on one door, UAL 811, and will be on another, TWA 800.
Now, why did aft mid span latch of forward cargo door rupture/fail/open? It could be unsequenced unlatching. UAL 811 may have been very synchronized and all opened so door flew off in only two pieces with small rupture. TWA 800 and others were slightly slower and large rupture occurred before all other latches could unlatch so big hole appeared and expelled baggage into engine number 3.
Aft midspan latch is culprit, it just may be the weakest area against the large internal air pressure force: fuselage flexing on old airplane and that was the weak spot. Anyway, why it failed is open to conjecture, but that is now datum of damage. And UAL 811 and PA 125 and UAL preflight inadvertent open doors were electrical problem from chafed wires to door motor and that is probably the same on TWA 800 and others.
The aft mid span latch large rupture explains why the lower latches were latched on TWA 800, the large rupture hole released the air pressure and blew the outer top of door up against the upper fuselage and left red paint smears.
In pictures and text, UAL 811 now matches TWA 800 in sudden loud sound, abrupt power cut to FDR, at least nine never recovered bodies, and now fuselage rupture start point at aft midspan latch of forward cargo door.
Boeing 747 UAL 811 aft midspan latch rupture
Schematic0 Door Drawing latch pins
Boeing 747 nose picts right side cargo door
AD Airworthiness Directive 79-17-02
Airworthiness Directive Amendment to 89-05-54 amending 88-12-04
Airworthiness Directive 88-12-04 Boeing 747
More pictures of UAL 811 cargo door hole
Cargo door accidents