ok  

Gear up and tucked has no bearing on what a blown float will do to a door.  Remember there are squibs and explosive links in a 76 float inflation system and it don't give a s--- what positon your gear handle is in if it decides to go.

This case happened to have a sagging wiring bundle in the over head that should have been securly fastened to the ceiling with tyewraps but those had long since dry rotted in a area not easily visible during inspections.  That heavy wiring bundle ended up sagging down enough it rested on a rivet line that then began to eat and chafe into the outer most strands of wire in the bundle.  Those outer most strands just happened to be the power wires that went to the rh main landing gear float bottle squib.  Normally those power wires would be in the armed state and just waiting for the pilot to lift the safety cap over his inflate plunger on the cyclic grip and smash down.  Well.....there happened to be another wire adjacent to that squib wire....and it had power already on it.  Older Kapton wire is well known to get super crappy and develop cracks in the insulation as it ages and this wire didn't need much persuasion to allow an arc across from power to ground or power to the now exposed squib wire.  You get the idea.  Boom.  Insta air brakes at cruise.  But Mr. wizard, you say, that would have only inflated 1 float, and to that I say you would be correct in that understanding, but this is a redundant system with relays and dual bus backups, Primary and Essential.....and power can backfeed, and it did. Boom, all floats deploy. 

That's all you get for today.  Story time is over.

Go away now.