747 technical question...

[Dude~]

I wonder if anyone can help me with the answer to a couple of questions I have come up with since starting work loading freight onto 747s?

Firstly, how much does the main nose cargo door weigh on a 747 freighter? I never cease to wonder at the strenght of the hinges and the two arms that raise the door - they seem far too short for the job!

Also, how high is the main deck of a 747 off the ground - ie, if it were a pax aircraft, how far woulf the pasengers feet be off the ground?

Finally, on the 747-400, do the inboard and middle slats retract upn touchdown as I have notices them extending whenever the 400s turn off the runway. Are they perhaps retracted when the spolier deploy after touchdown?

Any comments gratefully received!!

[fesmokie]

1) I can only speak for the Classic. I have No idea how much the nose door weight is but it can be operated up to a wind speed of 40 knots and can handle 65 knots while open.
2) The height of the main deck is approx. 16 feet above the ground.
3) Leading edge slats 2 & 4 are retracted when flaps are selected up. They extend when flaps are selected to "1" and outboard flaps are out of the up position. Normally the crew will not select flaps up until clear of the runway.

[Thunderbug]

Dude

Ref the -400 flaps


During engine reverse (idle or greater...) the inboard & midspan leading edge flaps retract.

Very Eagle-eyed of you. During the landing roll, the reversers will be deployed and those sections of LE flap retract. As you turn off the runway the reversers are stowed and the flaps then deploy again to their original positions

T'bug :ok:

[Mr Levitator]

What purpose does that have? Would the jet wash from the reverse thrust impinging on the LE devices backwards damage them??

[gas path]

Mr Levitator, you've got it in one:ok:
Also the last of the classics had the same 'modus operandi'

[Dude~]

Thanks guys,

Since I work very close to the runway, and right where BA 747-400s turn off I often notice that as they are vacating the runway their slats extend, then they retract all the flaps and slats together, but I hadn't thought of linking it to possible reverse thrust damage - I thought it was perhaps to aid lift dumping.

Cheers for clearing that up!

[CR2]

Nose-door is roughly 7000KG. Those jackscrews open/close the door in 2 mins.

fesmokie quite correct concerning windspeeds.

Maindeck height depends on aircraft weight. We use 5.5m as a rough guide.

[747FOCAL]

Is it reverse thrust damage or does it have the same issue as the original 737? :E