Floor loading

[ft]

I’m interested in the maximum permissible floor loading for various types, and how it is specified, in both cabin and cargo areas.

Ideally, this includes any allowances made for use of spreaders etc.

Very grateful for any help. Regards,
/Fred

[MasterBates]

If this question is to be answered, it may result in a requirement that 50% of the American nation must be boarded in shoes size 20+ (American numbers) for weight distribution. :ok:

[744rules]

All these figures can be found in the weight and balance manual

[ft]

MasterBates,
so I'm not the only one who has noticed? Oh well, the usual application of common sense seems to solve that problem. I have yet to have anyone fall through the floorboards! :D

(Although high heels would be required off prior to boarding as well as before hitting the slides if I could have my way...)

744,
wow! No kidding. And phone numbers can be found in the phone book, I suppose? :rolleyes: If I had a wealth of W&B manuals at hand I wouldn't be asking, would I?

Regards,
Fred

[Milt]

ft

Seems you are already on to the old problem re stilleto heels.

Did carpets help to solve that one or was there another solution?.

Then there are the floor support structure design specs.

These have probably been changed lately to account for floor collapses following explosive decompression pressure imbalance should a cargo door come open. May have been provided for by adequate floor vents.

I think you have opened up a new can of worms.

Should be some interesting illuminating responses.

See you again soon on the Yaw/Asymmetric/Sideslip thread.

[ft]

Carpets seem to solve the problem as far as the heels not punching holes in the floorboards. The force distribution is probably still way out of line around the heels though as carpets aren't all that stiff, but let's not think (leave alone mention) that! :D

Definitely a can of worms.

Yeah, explosive decompression is considered these days. For starters, you are not alloved to cover the entire cabin floor with cargo, spreaders or lining. There has to be gaps large enough for the blow-out panels to do their job.

I'll go over to the yaw thread and see what is brewing.

Regards,
Fred

[john_tullamarine]

We need to keep in mind that there are various limits to address .. including ..

(a) shear strength ... related to vertical tearing failures .. a bit like supporting a sheet of ply on two beams 5-6 inches apart .. and then driving a motor car wheel along the central bit of the ply

(b) bending strength .. related to failures like might occur by excessively loading the centre of a longish plank supported at each end on two ladders. Also, with longer aircraft, particularly, we are concerned with fuselage bending .. so there will often be limits which permit lots of load over the wing carrythrough section ... progressively reducing as the distance from the wing increases. Often a critical consideration with composite floors due to the sudden onset failure which can occur with composites.

(c) local bearing strength (crushing) considerations .. related to failures similar to what happens when you belt a surface with a hammer or put some sort of high load item with a small support footprint onto the surface.

From a practical point of view, the W&B (sometimes the AFM/POH) manual will detail the limitations and then it is up to the load control/freight people to get the sums right to avoid problems.

.. and, if a pilot/operator cheats ... the effect on calculated and specified fatigue lives can be compromised significantly ...

The general message with all limits is that they are there to protect the innocent ... one ventures outside the limits in ignorance of the specifics which went into their calculation.

[400F]

On the 742/744 Freighters we do the calculations based on Area Load Limit and Linear Load Limit. Both of these figures vary according to whether you are calculating for the nose/over-wing/tail sections. The most restrictive result for the above two calculations applies.

[ft]

john_t, spot on. Then there's shearing around the edges of the body applying the load, shearing around the edges of the panel, allowed loads on individual frames...

What I am after is how various manufacturers have condensed this abundance of limitations on what is a Good Thing To Do into something which:

a) is useful to the people actually doing the work

b) still allows anything at all to be loaded

Regards,
Fred

P.S. If we have a cargo of live birds flying around the cabin, what will the floor lo... no, I'll leave the lid on that one. ;)