Originally Posted by
DaveReidUK
What function do those springs have when a plug door is fitted?
It's clear what role they perform when a live door is being opened, but do we know they are even present when the aircraft has the plug door (which is only ever going to be opened on a check)?
I expect they are to lift the door to disengage the fingers. If the door was unable to move up then the fingers cannot release.
The question is, are the bolts at the springs situated in circular holes or in slots? If they are in slots to limit the travel of the door to just enough to clear the fingers that would make sense. It would ease the process of reinstalling the the door to the closed position. From the latest
chrisbrady b737.org.uk video there is a stop cap on the top of the guide that the springs are installed on. Since the guides appear to have remained with the plane and not been bent or twisted, but the caps didn't stay, how did that happen?
It seems more like the caps, the lower locking bolts, and the upper locking bolts were never installed before delivery and who knows what was holding the door from popping up and out. Someone put the door in on the springs and then shut it. Maybe they tightened the adjusters for the fingers enough to hold it in place with friction.
I am leaning toward the door having opened during the taxi or early after takeoff and the plastic interior panel plugging the leak until it could no longer be supported by the cable straps. Then the door was ejected by the lift springs and the interior panel was adios muchacho. It would not have moved if pressure was applied before it opened as that would have damaged the fingers around the frame.