Extra fuselage tube

[TimHicks]

See the picture attached.
In my 1946 BC-12D, there is a horizontal tube in the fuselage that is bolted in. It's smaller diameter than most of the regular fuselage tubes.
And it doesn't seem to do anything.
Maybe it is for the headliner (which my airplane has not had for 20 years).

Can anyone tell me if this is supposed to be there or not?

[crispy critter]

Re: Extra fuselage tube

It also has an extra X brace just below that over the baggage compartment that I've never seen before. Would that be a sea plane mod maybe???? I've had a couple of BC12D's that had been on floats but never had that X brace....just looks like an unlikely area to need it.

[TimHicks]

Re: Extra fuselage tube

You know, I never knew that those tubes didn't belong either.
So, to try to find another example, I visited Rob Lees' restoration site of G-BREY (which I believe is also a BC-12D).
Attached is a picture I found there which seems to confirm what Crispy says.

[Hank Jarrett]

Re: Extra fuselage tube

Looks like a tube to attach a shoulder harness to me. You would need to keep the attach close to the outside ends or it would just bend when the load hits it.
Hank

[crispy critter]

Re: Extra fuselage tube

Here's some of Crispy. Also, the last two pics are of a fuslage I covered & painted a few years ago, niether have the tubes in question.

[barnstmr]

Re: Extra fuselage tube

Whats the serial number? Does the airplane have a history of damage / repairs. Perhaps this is someone's misinterpretation of the Gilberti drawing # G-120 which shows 2 tubes added in a similar welded criss-cross, but between the bottom longerons in stead of the top of the baggage area.

[crispy critter]

Re: Extra fuselage tube

I was thinking the same thing Terry. The X brace is identical to what they call for in the STC but they go under the floor of the baggage area....but that still doesn't give any clue as to why the smaller tube is going across the top. Maybe hank is onto something but if your going to do the shoulder harness in this location why not use the large tube straight above it like soo many others have done in the past? Just doesn't make sense.

[barnstmr]

Re: Extra fuselage tube

I would venture a guess that the other tubes bolted in might be for headliner attachment.

[crispy critter]

Re: Extra fuselage tube

Possibly, could've also been used as a hanger rod.....to hang things from??

[TimHicks]

Re: Extra fuselage tube

I doubt that it was intended for shoulder harnesses. When I bought the airplane in 1993, it didn't have shoulder harnesses. But it did have a headliner. And there was no opening to pass the harnesses through the headliner. And when I added shoulder harnesses, there was no way I was going to that puny extra tube. Mine are wrapped around teh big tube above.
So that's a mystery. But what I'm taking away is that I can remove it without harm.

Regarding the x-brace. I noticed that the seatback bar is welded to the forward end of the x-brace.
Maybe it was added to allow the seat to be a little further aft? Are your seatback tubes welded to your B-pillars?

My serial number is 9172.

[barnstmr]

Re: Extra fuselage tube

Does your airplane have an original seat sling or has it been modified with some non factory seat?

[crispy critter]

Re: Extra fuselage tube

Wow, Bingo Tim, you just hit the nail on the head. Compare where the seat bare is on yours compared to the pics of mine and Robs. It is moved back about 2-3 inches. The X brace is to move the top of the seat sling back to allow more room. Damn I wish I had seen this idea before I covered the fuslage on Crispy, I might have done this myself. I still don't know about the small bolt on tube up top.

[TimHicks]

Re: Extra fuselage tube

I use a standard seat sling. I just replaced it a couple of years ago with a stock TCraft seat sling from Aircraft spruce.

I never put 2 + 2 together previously. But I have noticed in the past that my seat sling and my baggage compartment had ill-fitting notches where the Xtra-brace passes across them. And notice that piece of wood at the back of the baggage compartment. I fashioned that to attach at the standard mounts yet avoid the Xtra-brace (which is right in-line with the attach points). I couldn't figure why everyone else didn't have the same PITA problem.
I stand North of 6' 4 " tall. So I'm obviously content to leave this alone. But thanks, everyone, for helping me understand these anomalies.

[crispy critter]

Re: Extra fuselage tube

I'm also 6'4" and that would have been a good upgrade for Crispy.

[BlueRidge]

Re: Extra fuselage tube

Wow, Bingo Tim, you just hit the nail on the head. Compare where the seat bare is on yours compared to the pics of mine and Robs. It is moved back about 2-3 inches. The X brace is to move the top of the seat sling back to allow more room. Damn I wish I had seen this idea before I covered the fuslage on Crispy, I might have done this myself. I still don't know about the small bolt on tube up top.


Does this modification require some kind of paperwork? Or can it just be done?