Thanks, all helpful. I actually rejigged the scene I was writing - a character wants to get down into the hold to a coffin that's being transported back to the UK, but ends up just going loony instead and pulling open doors before being restrained...
I think it actually turned out better that way... I'm always sceptical of films set in aircraft that have reams of corridors and trapdoors.
I'm sure I saw one where someone went down into a computer in the nose cone?!?