Dent behind propane bottles?

[CA_Tallguy]

Hey folks, I'm wondering if any of you can help me understand what might be going on behind my propane bottles on my 77. It looks to me that the center panel back there is dented in but for the life of me I can't figure out how something like that might have happened. It clearly looks like something isn't right as there is a lot of filler vulkem around the battery doors, broken rivets to attach them, etc. Is there any natural indentation in this location? I am 70% sure this is damage vs a natural indentation for the vent or some other reason. (Why is there a vent here anyway?)

Not asking what I might have done to cause this as this is certainly a pre-existing condition to my ownership, but I would like to try to understand what may be going on and how it may have occurred so I can know if I need to worry about anything but fixing it.

[perryg114]

I think something hit that vent on the left side and buckled that panel. It looks like you have some potential leaks around the battery boxes. I would pull the coucho and see what the floor looks like back there. You want to make sure you don't have front end separation. What is that center vent for? I would also strongly consider getting rid of that undercoating gunk on there.

That area between those battery boxes is a structural attach point and the buckling maybe because the front of the trailer is being supported by very little sheet metal between the two battery boxes and that vent that does not look factory.

Here is what mine looks like on the inside. This is before I replaced the battery boxes and yours are probably shot by the way.



Perry

[ROBERT CROSS]

Front end separation?

Bob

[4RXLA]

Could be a couple things. 1) that trailer originally had a large plastic compartment behind the tanks that housed the Excella-vac vacuum brake booster. The placement of that compartment could have pushed in the skin. 2) the battery boxes are supported by wood blocks. It looks to me like both plastic boxes have lost this wood block and have fallen to the floor, which has caused the aluminum skin to separate from the box doors causing the gap that will leak if not sealed. Both my battery boxes had to be repaired and resealed. You will need to take a look from inside the trailer. Make sure those plastic boxes are firmly supported and then use long enough screws to join the metal door frame with the plastic box and seal properly. I doubt you have front end separation as you appear to have the hold down plate as evidenced by all the rivets between the 2 doors.

[CA_Tallguy]

Wow, I'm glad I asked about this as there is a lot going on in the front here. Good to know that I may have the hold down plates. I'm going to research front end separation anyway just to try to learn about the structural and motion dynamics in the front of the trailer. I'm clueless in this regard.

I was planning to remove the battery boxes at some point anyway as they don't fit my current batteries. I don't know what the vent is there for. As for the vacuum brakes, I may have had those as it is referenced in my owners manual.

Can I reskin that section using simple flat alclad aluminum stock of the right type? Or do I need to order a replacement panel for that part? Awhile back, when thinking about a patch panel, I researched suppliers of the right kind of aluminum for airstreams and found a local place where I might be able to buy it. This section looks like it should be almost flat. Since it has all this rock guard gunk on it and I want to remove the battery doors, and with the body damage, I might as well just replace it.

[perryg114]

You could go a little thicker on that panel but yes you can use off the shelf stuff to replace it with. It looks like you have a hold down plate at the bottom and you want to retain that or make a stronger one. Also make sure you have the stringers on each side of the boxes. You can just eliminate the boxes all together with the new panel. I would definately buck rivet as opposed to the olympic pop rivets. You can work out any dents on the corners while you have everything off as well. Pull all that fiberglass out and replace with ridged foam board and maybe some radiation barrier.

Perry

[AldeanFan]

My bet is someone backed in to the front panel or they hit the propane tanks and pushed the tanks in to the front panel.

Check propane tank mount to see if it has been repaired.

The panel is flat or mostly flat, but the ribs may be bent. Good luck

[CA_Tallguy]

Originally Posted by AldeanFan

My bet is someone backed in to the front panel or they hit the propane tanks and pushed the tanks in to the front panel.

Check propane tank mount to see if it has been repaired.

The panel is flat or mostly flat, but the ribs may be bent. Good luck

I wonder the same thing but with the tongue in be way and the bottles mounted a foot from the shell, I can't see how that would have happened. It does seem like it was dented somehow but for the life of me I can't see how it would have happened with the tongue in the way. The only thing I can imagine, and it seems like a stretch, is that the rear overhang of a truck came in from the side and above the tongue?

If that hydraulic box previously mentioned was mounted behind the bottles, then maybe it was more likely.

[4RXLA]

The hydraulics box could have been broken by someone backing into the tanks and would have made that kind of dent.

[CA_Tallguy]

Any suggestions on removing the bed liner material? I will eventually be polishing the trailer and suspect theses panels will absolutely need it after that. Also, they will be covered by those corner rock guard things at some point.

But replacing them may not be all that difficult while I am doing the center panel. Hmm.

[FL Crackers]

Okay, here's a POSSIBLE scenario based upon how my '77 looked when I picked her up. You can see the box behind the propane tanks that housed the hydraulic brake system and how close they were. You will also note the same vent above the box. In the next photo, you can see how minimal the contact is between the tank and the tongue frame. If it's not tightened down from above, the tanks can kinda pivot inside that little knub that sticks up. Now imagine that you're inexperienced at backing up and the turn gets away from you. Could a bike or some other attachment to the TV bumper make contact with the tank and/or the brake housing in a jackknife? (Don't ask how I dreamed that up.)
As for the vent. I suspect it provided cooling ventilation for the huge heat-producing univolt system that they installed on the interior wall. (last pic)

[CA_Tallguy]

Oh wow, now it is making more sense. Yeah, that box must have been pushed in!

[CA_Tallguy]

Am I likely going to need to replace the ribs or is there a good chances can salvage them? I'm guessing the few under the window are going to be bent a bit.

[CA_Tallguy]

FYI for anyone looking at the same repair.... I've been reading a lot of threads trying to verify what aluminum to use for my 1977 trailer. A PDF floating around talked about airstream using 3004 aluminum in 1977 and 78, but I'm pretty sure that my service manual contradicts that. It says "alclad aluminum" for the major side panels -- .040 down low and .032 for the roof. Then under the panels for the front and back, it says that middle section is .050

The manual only seems to spec out 3004 for the banana wrap and belly pan.

I am assuming that "alclad aluminum" is 2024-T3 alclad

[CA_Tallguy]

Pic from the inside of the trailer behind that center panel. Damage is certainly more evident. I'm surprised there are no vertical supports in this area. The only structure in here is a frame for where I guess the brake booster box was on the tongue.



I'm wondering if I should add additional structure in here while repairing it.

[CA_Tallguy]

Help! I'm trying to remove this center panel and I'm wondering if it can be done without removing the center window. Anyone know? I think that I have all the rivets that I can see out but the panel isn't budging. It feels like something is still holding it at the corners to the window frame. If so, I'm nearly certain it isn't a rivet that comes all the way through. I'm wondering if highly "tacked" this panel in place before installing the window on top and those "tack" rivets are now the problem. That's my best theory right now. I've been going at the panel with a torch and hot knife trying to get as much sealant out from under the lip of the window frame. It is only wiggling as much as it might from a rivet with a. Elongated hole or something. The sides and bottom of the panel are free in the wind and I was thinking this panel should just slide out from under the window frame lip (visible rivets removed from the frame) but no dice.

[Aerowood]

Probably just a portion of a drilled out rivet. Use a sharpened putty knife and drive it up between the the window frame and the skin with a hammer. that should shear any rivet residue. A thick layer of sealant can also cause problems also.

[Alumaholic]

In a 1976 I was owned, that type of dent was caused by frame failure where the "A" frame of the tongue is joined to the frame. Moisture runs down the top of the protruding tongue members and collects where tongue meets frame (behind the skin).
As weld fails, tongue actually starts to bend upward, imperceptible to visual inspection, but enough to crimp aluminum skin as yours has done.
Mine was repaired from the bottom by removing portion of belly pan.
There is a thread on this where other Air Forums member had same issue.
Will try to find.

[FL Crackers]

I'm having a hard time visualizing the problem. Did you remove the screen frame from around that front, center window? Removing the frame doesn't remove the window. I found hidden rivets behind the screen frame on the rear window of mine when I was searching for leaks.

[perryg114]

Can you post a photo of the damage from the left side. In other words a photo facing the front of the trailer from the inside and far enough back so we can see what the structure looks like.

Perry