Z Brackets dont line up!!!!!

[danielhv]

Ok, im panicing right now because I was installing the tank onto the spar and the holes for the Z brackets dont line up perfectly with the holes in the spar! They are just a tad off. What do I do?? I followed the process on rvproject.com for match drilling the Z brackets to the spar... BUT, I had to replace the rear baffle... I know I got the Z brackets back on in the correct order. Man, its like 1 step forward, 3 back. I wish I bought a QB.

-Daniel

 

[Brantel]

Don't panic....

How far are they off? How much is "Just a Tad"?

If it is a slight amount, you might be able to open the holes slightly to get the bolts in....

 

[fstringham7a]

RE:Kep on keep on

Ok, im panicing right now because I was installing the tank onto the spar and the holes for the Z brackets dont line up perfectly with the holes in the spar! They are just a tad off. What do I do?? I followed the process on rvproject.com for match drilling the Z brackets to the spar... BUT, I had to replace the rear baffle... I know I got the Z brackets back on in the correct order. Man, its like 1 step forward, 3 back. I wish I bought a QB.

-Daniel

Hi Daniel

Part of the learning ,at least for me, were the frustrating moments of 1 step forward 4 steps back.

There were many times I wished I had bought the QB.....but....now that it is just about done.....2.5 years longer than anticipated and 35 k over budget....
I can look back on most of those learning experiences (@#$#@&&*^^%) as just that!!! Not really problems made but solutions to be sought.

I agree with the previous post...What is a Tad....if small differences give it a bit of a custom fit with the file and move on. In the end there is a whole bunch of stuff holding those tanks on!

Good Luck and let us know your solution.

Frank @ 1L8 ...RV7A... Just about to start the engine!!!!!!!!!!!

 

[danielhv]

Don't panic....

How far are they off? How much is "Just a Tad"?

If it is a slight amount, you might be able to open the holes slightly to get the bolts in....

Here are the pics... they are in order from inboard to outboard. The inboard holes arent as bad as the outboard, so #6 (last pic) is the worst The washer marks on the spar are from the previous installation (when everything DID line up!)

Thanks for any help guys, I really appreciate it.

 

[scard]

Daniel,
It looks to me that you are just fighting "the magic sequence". Some of these such things require you to get in tune with the universe and accept that sometimes the sequence of assembly or bolt/screw insertion is key. Really.
Pull all of the skin screws out first. Then maybe see if you can get, reasonably without really pulling on anything, one bolt in each Z-bracket. Maybe the middle one? Then... The magic sequence.

 

[chaskuss]

Are the nut plates installed?

Dan,
IF you have not yet fitted the nut plates to the Z channels yet, this "might" be an easy fix. I would check with Vans to see what they think of my suggestions.

#1 Drill out the rivets holding the Z brackets to the rear baffle and fabricate replacement Z brackets. You will have to remove the access cover, tip the tank with the inboard end down and shake the tank to remove the remnants of the old rivets.

#2 IF (big IF) the Z brackets are fabricated from 6061-T6, the holes could be welded closed, the contact surfaces filed flat and the offending holes re-drilled. Keeping the heat from transferring to the ProSeal between the Z channel and the rear baffle would be the major issue here. I would suggest wrapping a damp rag around the Z bracket during the welding to prevent heat transfer.

Charlie Kuss

 

[danielhv]

Daniel,
It looks to me that you are just fighting "the magic sequence". Some of these such things require you to get in tune with the universe and accept that sometimes the sequence of assembly or bolt/screw insertion is key. Really.
Pull all of the skin screws out first. Then maybe see if you can get, reasonably without really pulling on anything, one bolt in each Z-bracket. Maybe the middle one? Then... The magic sequence.

Yea, I tried doing that. It creates a bow on the top side of the skin where it sits flush with the LE skin.

 

[Michael Burbidge]

I thought that my z-brackets were messed up at first also. The key is the order. What I did is removed all skin to spar screws. Then I started with 1 bolt in each z-bracket. I did not tighten the bolt. I then put the other two bolts in all z-brackets. Again I did not tighten any of the bolts until all bolts were in place. Finally I torqued all bolts in each z-bracket.

When you do this it will look like the top skin is not aligned correctly. It will stick out and I thought, oh boy I don't have the z-brackets centered. But once I started putting the screws in the skins I could see that the top skin actually was supposed to have a little curve to it. When the screws were all in the contour from tank to skin was gradual and perfect, even though a little curved.

 

[sglynn]

open web holes

What do you guys think about opening the web holes slightly, like one or two number bigger in drill bit size? That would give it just a little more flexibility in getting the bolts in. And with all the bolts in I doubt it would move.

 

[Loman]

Worst case scenario

Having tried everything else first, what about cutting off the aft flange of all (or maybe just the worst) Z brackets and riveting on a suitable piece of angle to give you a new flange? These could be back- drilled through the spar while the skin is screwed in place for a perfect fit. Just an idea - I haven't thought it through.

If you are widening the holes, the nutplates will still be in the wrong position. Repositioning them would be possible (rotated 45 deg to give edge distance from the old lug holes) except how are you going to get access to mark the new position?

I would be surprised if the solution to this takes you more than a day in the shop to implement so it's not a full- blown disaster. I have had worse and I suspect most of us are the same.

Loman

 

[FredMagare]

Don't Worry

Daniel,

Scratch your head a bit and you'll think of something. I had just one of my nutplates misaligned which caused repeated stripped bolts. I opened the hole a bit and it was fine.

If the misalignment is more serious...new baffle and z-brackets or purchase pre-built tanks....

The difficulties we overcome in these projects are what give us our sense of accomplishment! What's the challenge if it's easy?

Good luck!

 

[airguy]

Daniel,

Scratch your head a bit and you'll think of something. I had just one of my nutplates misaligned which caused repeated stripped bolts. I opened the hole a bit and it was fine.

Same experience here, with one bolt, and same solution.

 

[chaskuss]

Scab Flanges

Having tried everything else first, what about cutting off the aft flange of all (or maybe just the worst) Z brackets and riveting on a suitable piece of angle to give you a new flange? These could be back- drilled through the spar while the skin is screwed in place for a perfect fit. Just an idea - I haven't thought it through.

snipped
Loman

Loman,
What you describe is referred to as a scab flange. Due to lack of work space, this would be EXTREMELY difficult (if not impossible) to do, on all but the end Z brackets.
Charlie Kuss

 

[chaskuss]

An idea

I thought that my z-brackets were messed up at first also. The key is the order. snipped

The quote above gave me an idea. Daniel, is it possible that you may not have re-installed some of the Z brackets in their original positions? If this is a possibility, Perhaps you should drill out the rivets holding the offending Z brackets to the rear baffle. This would allow you to try other positions using clecos, till you hit upon the correct combination. You will probably need "half height" clecos to do this.
Charlie Kuss

What, me make a mistake? It never happened. That's my story and I'm sticking to it!

 

[danielhv]

The quote above gave me an idea. Daniel, is it possible that you may not have re-installed some of the Z brackets in their original positions? If this is a possibility, Perhaps you should drill out the rivets holding the offending Z brackets to the rear baffle. This would allow you to try other positions using clecos, till you hit upon the correct combination. You will probably need "half height" clecos to do this.
Charlie Kuss

What, me make a mistake? It never happened. That's my story and I'm sticking to it!

I know for sure they are in the correct order. Each one was numbered, and I had the tank and baffle numbered w/ the corresponding Zbrackets. So if a different combonation will work, they would have to be out of order from the previous baffle... and pure luck! I know this is a "minor" setback... but this tank has given me such a hard time all together I am anxious to be done with it and move on. And just when I thought I had prevailed.... Makes me mad just thinking about it! hehe. I still dunno what Im going to do. Im going to shoot an email to the guys at vans and see if they have any thoughts as well...

 

[danielhv]

Ok, I just got off the phone with Vans Builder Assistance. Guss said to do one of two things... either elongate the holes so I can get a bolt in them, or force the Z bracket over far enough to get the bolts in and take it up to 50inch pounds. He said there is really no concern on sheer force in that area if the bolts are in a bind... as long as its holding the Z bracket against the spar it will be fine. *Whew!* He also said that he isn't suprised that they dont line up after replacing the rear baffle.

Im going to elongate the holes on the one that is the farthest off (last pic) and just use a pin to align the others to get a bolt in them. That makes my day so much better!!!!!

Thanks for all the help and suggestions guys! Hopefully someone else can learn from this in the future!

 

[chaskuss]

Ok, I just got off the phone with Vans Builder Assistance. snipped
Im going to elongate the holes on the one that is the farthest off (last pic) and just use a pin to align the others to get a bolt in them. That makes my day so much better!!!!!
snipped

How do you plan to locate, drill and rivet the nut plates onto the inner Z brackets? Since the Z bracket hole will be oblong, you will need to figure out a way to mark where to locate the plate nuts. Perhaps you could make a diagram on a piece of paper to aid you?
Charlie Kuss

 

[danielhv]

How do you plan to locate, drill and rivet the nut plates onto the inner Z brackets? Since the Z bracket hole will be oblong, you will need to figure out a way to mark where to locate the plate nuts. Perhaps you could make a diagram on a piece of paper to aid you?
Charlie Kuss

Im not following... the nutplates are already there. Im going to elongate the holes on the spar web so I can get a bolt into the Zbrackets.

 

[chaskuss]

Im not following... the nutplates are already there. Im going to elongate the holes on the spar web so I can get a bolt into the Zbrackets.

Sorry,
I didn't realize you already had the nut plates on. Vans said it was OK to oval the holes in the spar web. Hmmm?
Charlie

 

[danielhv]

Sorry,
I didn't realize you already had the nut plates on. Vans said it was OK to oval the holes in the spar web. Hmmm?
Charlie

Yes sir, Guss did. He even said "its just the sheet metal portion of the spar, so there its getting very little strength from the brackets anyway. He said they are simply to hold the z brackets against the spar, and with all the other screws and bolts in place, its not going anywhere. Just inspect it at each annual. Took me by suprise too!

 

[sjjonesnz]

I had the same problem...

...and solved it simply by pushing a small screwdriver through the centre hole. This pretty much lined up all of the holes (I levered the screwdriver slightly if they didn't) enough to get the first bolt into one of the other two holes - easy from there.

Quick, easy and didn't involve further cutting/drilling/breaking stuff.