Removable Baggage Floors, DWG 29

Question for 7 builders who did the removable baggage floor mod. F747 R&L
The baggage floor normally would carry nut plates with F706A for the bottom of F751 Lower Baggage Bulkhead to screw in place. The aft flange of the baggage floors are normally riveted to the F706A bulkhead and nutplates installed through both layers.
Question
Did you use the same screw holes for both baggage floors and lower baggage bulkhead?
OR
Did you install countersink nut plates specifically for the baggage floors using some or all of the #3 rivet holes? The other nutplates would still be used to hold the lower baggage bulkhead. Seems like a stronger solution.

Hi Larry,
If I understand the question right, I did the second option you list. I put in nutplates specifically for the aft group of holes in the floor, then used the nutplates in the 706 bulkhead to attach the baggage bulkhead cover and the flange for the floor plates. The screws in the floor are flush and the screws in the bulkhead are not. I have a blue sharpie note to myself on the baggage bulkhead and the inside tailcone top to make sure that all the screws are in place and tight before riveting the roof of the tailcone. Not sure if it maters but it seems proper to me. Let me know if you would like some pics. I hope I described what you were looking for.

Solution

Lemmingman said:

Hi Larry,
If I understand the question right, I did the second option you list. I put in nutplates specifically for the aft group of holes in the floor, then used the nutplates in the 706 bulkhead to attach the baggage bulkhead cover and the flange for the floor plates. The screws in the floor are flush and the screws in the bulkhead are not. I have a blue sharpie note to myself on the baggage bulkhead and the inside tailcone top to make sure that all the screws are in place and tight before riveting the roof of the tailcone. Not sure if it maters but it seems proper to me. Let me know if you would like some pics. I hope I described what you were looking for.

Click to expand...

Gil
I love it when someone else has the exact same solution I consider.
Yes, a few pics would be appreciated.
Specifically, I'm curious how many of the #3 holes were converted into countersunk nut plates for the baggage floor. So far, I'm looking at about every other hole.
Thanks.

I converted them all. During my research I found a reference or two where there was a question about the structural requirements of the baggage and seat floors. I found enough posts that felt that the rivets that held the floors in place are a structural component. I'll see if I can find the reference for you. Replacing the rivets with nutplates seemed like a good plan, but if I was going to do it I needed to make sure they were all replaced. Which is what I did. I'm not an engineer by training or trade so I simply went with what seemed right. I wouldn't only do every other rivet had I chosen to do the floors per the plan.

Nutplates

Thanks Gil.

Option 2 for me too...

Hi Larry,

I went with your "option 2" also. I replaced all of the rivets that were going to hold the F-747 baggage floors onto the F-706A bulkhead with dimpled, #8 screws and K1100-L08 nutplates. IIRC, there is one location in a corner where you'll need a "one lug" dimpled nutplate instead of the "two lug" (K1100) nutplates.

This way I can remove the F-751 Lower Baggage Bulkhead and still have screws supporting the baggage floors. I'll send you some pix Wednesday afternoon.

I also used flush screws on the baggage side covers too. Not much more work and I thought it looked nicer. I also decided to make the F-750 Aft Baggage Side Covers removable because every other cover was removable, I might as make ALL of them removable!!

I hope this helps.

Jeff

Plans

JRichichi said:

Hi Larry,

I went with your "option 2" also. I replaced all of the rivets that were going to hold the F-747 baggage floors onto the F-706A bulkhead with dimpled, #8 screws and K1100-L08 nutplates. IIRC, there is one location in a corner where you'll need a "one lug" dimpled nutplate instead of the "two lug" (K1100) nutplates.

This way I can remove the F-751 Lower Baggage Bulkhead and still have screws supporting the baggage floors. I'll send you some pix Wednesday afternoon.

I also used flush screws on the baggage side covers too. Not much more work and I thought it looked nicer. I also decided to make the F-750 Aft Baggage Side Covers removable because every other cover was removable, I might as make ALL of them removable!!

I hope this helps.

Jeff

Click to expand...

Thanks Jeff. That's the plan.

Why?

Why do you want removable floors? I did it on one -7 and decided it was too much like work to make the same mod on others.

Don't overlook the difficulties you will encounter trying to cram plate nuts into the intersection of the center bag ribs and the rear spar bulkhead, especially the AN3 bolts holding the flap shaft's center bearing. Also, the vertical support for the seat back brace rests on these ribs, and you will need to locate its plate nuts amongst the others. IIRC, there could be interference if you don't look ahead. Also, sitting here and not at the airplane, I think the flap shaft pretty well blocks reaching screws under it with a driver; you'd need to remove the flap shaft to get to them.

I did change all the rivets to flat. Also, the ELT is located between a pair of ribs so there I fabbed a removable hatch. A whole lot less effort, and what's removable has a definite purpose. With a wee bit of forethought, planning bushings and conduits for wire routing obviates any need for removing floors on that account.

John Siebold

I used nutplates in the floor but kept the rivets in the flange. Why? Because I wasn't looking for a removable floor as much as I was interested in just being able to get at the sub area of the baggage compartment for inspection, specifically the condition of the steps.

Floors

It's a done deal. All the floor nut plates are installed except for the area in question. Baggage area is flush. Seat area is standard screws.

Now I guess I need some input on how other tackled the issues mentioned. Seat back braces, flap shaft and bearing?