Fuel tank attach Z's on wrong

SOMETING WONG!!!

After feeling pretty good about completing both fuel tanks with no apperant leaks, I lined them up on the work bench and discovered I reversed the middle three T-1012 tank attach Z brackets on the right tank. What to do now)???

1. Drill out the six AD-42H rivets on all three reversed Z's (18 total) leaving the shavings and rivet pieces in the fuel tank forever (of course trying to shake them out through the fuel cap as much as possible). Doubt that too much will come out though. Then installing them facing the correct way. If I do this option will just twirling the new AD-42H rivets in fresh proseal and putting a fresh smear on the tank baffle after thoroughly cleaning it be enough to insure no leaks???

2. Drill three new holes for each of the three center reversed attach Z's in the main spar (9 new holes total) and attaching them that way. Can be done with a good template. Would that weaken the spar with 9 new holes in it and not using the 9 original holes? Would the stress transmitted to the new holes effect the structure of the spar in a negative way? New holes would be close to old ones by about 1 1/2 inches and appear to spread the load evenly. All bolts to attach tank z brackets would still be accessible through the three inspection holes in the lower wing skin. There are no interference issues as well.

Any advice would be helpfull.

Thanks in advance...

Rich

At least you`re not in any real bother Rich. There`s always a correct way to fix things. It might not be easy but it can be done.

If you carefully drill the rivets and remove the Z-brackets, the drilling swarf will be outside the tank, not in it. The AD-42H rivet tails are closed on the end and will have a small steel (magnetic!) core remaining inside them when you carefully punch them through into the tank.

I`ll bet you can eventually shake them all down to one end of the tank.

From there you should be able to retrieve and account for all of them with a vacuum hose or a neodymium magnet from your local craft shop attached to a string or some such rig of your own design. Masking tape on a stick works in some situations too.

The final step is to count them and make sure you have them all.

Wet installing the new rivets will prevent leaks.

DON`T DRILL ADDITIONAL HOLES IN THE WING SPAR WITHOUT APPROVAL FROM VANS!

Been there done that

Had similar problem. I put brackets in reverse order, placing bracket 1 on the wrong side of the tank. To my surprise, I had to drill out only one bracket, others actually fit fine. Made and installed new one. I was lucky, my bracket was in the bay where fuel cap is, so I could get rivet bottoms out thru the hole, However, because of heat when drilling it made bottoms stick to very conspicuous places. I ended up lowering my web cam on the stick to find them... I found all of the 5 steel studs and bottoms with pro seal on them. I got all of the smallest particles out (I think). Try to attach the tank so you can see if and what you need to correct.

hayabusa said:

At least you`re not in any real bother Rich. There`s always a correct way to fix things. It might not be easy but it can be done.

If you carefully drill the rivets and remove the Z-brackets, the drilling swarf will be outside the tank, not in it. The AD-42H rivet tails are closed on the end and will have a small steel (magnetic!) core remaining inside them when you carefully punch them through into the tank.

I`ll bet you can eventually shake them all down to one end of the tank.

From there you should be able to retrieve and account for all of them with a vacuum hose or a neodymium magnet from your local craft shop attached to a string or some such rig of your own design. Masking tape on a stick works in some situations too.

The final step is to count them and make sure you have them all.

Wet installing the new rivets will prevent leaks.

DON`T DRILL ADDITIONAL HOLES IN THE WING SPAR WITHOUT APPROVAL FROM VANS!

Click to expand...

I will be calling Vans tomorrow morning to ask their opinion as well.

Thanks for your comments...Much appreciated

Rich

AK-Models said:

Had similar problem. I put brackets in reverse order, placing bracket 1 on the wrong side of the tank. To my surprise, I had to drill out only one bracket, others actually fit fine. Made and installed new one. I was lucky, my bracket was in the bay where fuel cap is, so I could get rivet bottoms out thru the hole, However, because of heat when drilling it made bottoms stick to very conspicuous places. I ended up lowering my web cam on the stick to find them... I found all of the 5 steel studs and bottoms with pro seal on them. I got all of the smallest particles out (I think). Try to attach the tank so you can see if and what you need to correct.

Click to expand...

Thanks for your comments, much appreciated

Rich

z's

Sorry to here about your costly error. On my glastar I lost a rivet inside the flap and faced with undoing several rivits I was able to get something like proseal on it and leave it inside the flap stuck to a rib. good luck

It's always a bummer when you discover a mistake like this!

The first thing that popped into my mind is the fuel tank leak repair method that cuts large diameter holes in the back of the tank should allow you to get in there and clean out any debris created from drilling out the rivets. You may even cut the holes and get a shop vac hose running while the drilling operation is underway. There has to be quite a few RVs flying around out there that had leaky tanks repaired with this method. Just a thought...looking forward to hearing what the Vans recommendation is....

Vans said to not drill the spar, but to drill the rivets out of the Z brackets and turn them around to face the proper way.

Kind of thought that's the way it was going to go.

Instead of all the whining I did I could have just sucked it up and done that in the first place.

Turns out it only took me a couple hours to drill out the rivets and clean up the pro-seal on the brackets and the rear tank baffle. I ordered some more 42H pop rivets and when they come I am sure it will only take a couple of hours more to pro-seal it back together correctly.

I did vacuum as I drilled to keep all the shavings out of the tank. Trying to get the rivet remnants out will be a different story though. I can hear them rattle a little when I shake the tank. When the new pro-seal is fully cured I will put in a gallon of fuel and try and swish it around to get the remnants out.

Lesson learned. Like measure twice and cut once, look at the plans more than twice before riveting anything together, then look at them again before...

Thanks again for all the advice,

Rich

Good to hear you`re getting it sorted. You WILL be able to retrieve all the rivet tails, it will just take time. That`s the nature of aircraft!
There`s a right way to do something, and a shortcut that can end up taking longer and can cost a lot more in the end!

Just a suggestion Rich, if you`re ever thinking about deviating from the plans like drilling an "extra" hole, ask yourself what you are doing it in accordance with before you start.
Is it allowed for in the scope of the drawings?
Have Vans approved it?
Is it covered in AC43.13?

Keep up the good work!