Busy Preparing for the Fuel Tanks and Tech Counselor Checks out my LE

My Technical Counselor and former long time EAA Chapter 301 President Jim Elliot has been mentoring me through all this LE mod fiasco. I had to wait a couple of weeks for him to become available to come and visit the "almost" finished LE work, and he was finally able to come out last Saturday and take a look. He is a Mooney aircraft owner and has helped several people build different makes and models of experimental airplanes. He definitely knows his way around an airplane, and with evaluating potential affects of modifications such as mine. More on that in a bit.

Since I knew I had to wait for a bit for him to be able to come over, I started preparing (for about the third time now) to get back to work on the fuel tanks. So although I have not posted in while, I have still been very busy thinking, reviewing, and planning for re-engaging on the fuel tanks to get those behind me as soon as possible. his started with a review of many previous posts where I actually started on the left fuel tank because you needed to match it up with the LE to check alignment and drill some holes in the T-712 mounting brackets for the wing spar and the rear tank baffle. This little journey took me clear back to posts from the Fall of 2017. About the last thing I remember about the tanks was fabricating the tank stiffeners for the bottom of the fuel tank skin, and countersinking skin-to-rear baffle holes per the plans.

After reviewing the stuff from the past, I ended up coming up with a list of new additional questions that required answers from Vans. As a side note, to date I have order at least 2 proseal tubes, a small sized can of proseal, and a full sized quart of proseal - ALL of which have shelf lives that have long since expired, so they will not be used to seal any part of my fuel tanks, and I will need to put in an order for more proseal yet again. Sucks to be me I guess - that's about the only way I can sum that up.

Many of these additional questions are questions that you do not see either asked or answered by others, but I find it quite strange that others are not asking the same questions. Anyway, to make sure that I don't lose the content, I am posting them here for myself and anyone else following my blog that might also appreciate the info:

385b and c SW fuel senders - for left and right - is it correct that the potentiometer scale/meter on c version for the right tank will be reversed (facing forward instead of to the rear, when installed on the side of the tank, or should the scale for both still appear toward the rear of the tank when installed correctly.

Vans says this backwards orientation is normal - important thing is that they both point down when installed either on the end rib or the rear baffle plate.

Am I supposed to scuff the back side of the sender flange of each sender if I am going to proseal it directly to the tank rib (NOT use the rubber gasket or cork as recommended by many who have been there before.)

Vans says not needed.

The left sender seems to have a dead spot at the end of travel of the arm (empty indication) - either no ohms reading at all or much higher (300 ohms or more - much higher than expected 240 ohms per the plans.) The right sender seems to be indicating correctly per the palns info. Ordered both SW senders from Vans on 4-16-18 order # 74191. SW says has a 2 year limited warranty - how do I proceed with a replacement. Go through Vans or direct with SW?

vans - Contact SW directly to replace it

Left tank will be flop tubed, so sender will be in bay #2 in rear of baffle.
1. Did I do a lot of extra unnecessary work by cutting the big hole in the aft of the end rib, when I found out that the sender needed to be placed in the second bay via the baffle in the first place.

Vans   -still good to have access t that bay due to the trap door and the flop tube/anti hangup bracket attachments.

2. With the sender in the secnod bay of the rear baffle, that means that the only way I can service that sender if necessary is to pull the entire tank, correct?

Vans - correct - you will have to pull the tank to service the sender that is mounted this way

3. For tank baffle mounted sender, do I need to cut another big round hole in the second bay AND use a reinforcement ring (T-407) as well, or just the hole big enough for the sender to fit in?

Vans says nope - no reinforcement ring or big hole needed - just a hope big enough for the sender to be inserted/mounted directly onto the rear baffle plate web. No reinforcement ring needed because the baffle plate is thicker/stiffer than the rib web.

4. Do I need to use another reinforcement stiffener ring for the T-411 cover plate on rib T-703 if no sender is being mounted in that hole, or can I just mount the cover plate, with nut plates mounted on the rib web itself instead of the combo of the rib web and the reinforcement ring?

Vans - would still use the stiffener ring here as the rib is not very thick and alot of strngth is removed by cutting that big hole.

5. Depth of tank for SW sender specs to determine what size to cut the rod - what dimension should I use for that (tank depth so I cut the rod to the correct length?

Vans - just clamp the sender in place and measure to determine based on the area where the float will be traveling.

6. Since the left tank sender will go in the rear tank baffle, do the dimensions of the float wire change from original plans for mounting in the rib on the side? Any issues with clearance of the bottom stiffeners when mounting the sending in the rear tank baffle?

Vans - measure to be sure, but should not be a change or a problem as far as they are aware.

7. Do you know a part number for a more malleable proseal for access plates that is not as hard as normal proseal to remove??

Vans - they do not use it and did not know the part number of hand - said to check Spruce and others.

8. Grounding the sender - how is this grounded to the airframe if you have the tank baffle or rib web, proseal, and the flange of the sender on the thin later of proseal. Are we supposed to run an additional ground wire from one of the sender mounting screw holes to one of the tank attach bolts or something similar?

Vans - Use a lock nut with the cut flanges that bites into the metal on the underside of the screw head and on the sender flange as it gets mashed down during screw tightening to establish contact for a good ground - so additional wire should be needed, even if screws are prosealed. Do it on all screws or just one or something in between?

As far as the tech counselor visit is concerned, Jim took a look at my unfortunate demise on the LE. Said that it is a dent and not a crease, but that it did deform the outer skin and the subskin. Then we had a conversation about acquiring an autobody or planishing hammer and a dolly that may have to be customized to try to pound (actually TAPPED) out to try to reform the skin back to the shape that it was in before. Unfortunately I can see where my unbelieveably STUPID idea t just keep pounding on the skin with the rivet gun when the rivet was not setting properly has indeed flattened it out a bit. So as a result, if I want to continue with the LE mod using what I have done thus far, I now get to learn a new skill that involves removing dents and reshaping metal, and I probably have to custom-make yet another tool = more wasted time.

So I went to local NAPA store, found a planishing hammer with a rounded head (NOT the kit you find at Harbor Freight, that only has flat headed hammers), and a Toe dolly that, when I fitted it up against the curvature of one of my LE ribs that I took with me to the store, looks like it will almost perfectly conform to the curvature of the LE skin/subskin/rib as long as it is held in the correct position. This is probably going to require a helper to hold the dolly in position while I tap the outer skin and hope like hell that I don't just deform everything beyond reasonable repair.

The last part of our visit was spent having a heart to heart about the possible structural impacts of what I am trying to do, and if I should go ahead and contact a DER (Designated Engineering Representative) to come and look at my invention and provide some further experienced insight on what I am doing. I wanted to go ahead and finish this mod regardless of the ultimate decision about its feasibility, just to see what it would take. At the end of the day I am not certain that this is a safe thing to do, and may still decide to abandon it all together. But I'm not throwing in the towel on the mod just yet.

I've got some parts to order from a number o different vendors so I am also putting that list together. I'll have some pics on the next post that show the damage from the F'd up riveting job  more clearly, and the tools I am going to attempt to use to fix it.

Cutting to the Chase

Well, the next logical sequence of this long drawn out process would have been to go through the steps to rivet the top side of the LE ribs together after finishing up the ones on the bottom. However, right now I think its just best to cut to the chase and remind any readers following this blog that deviating from the plans always involves risk.

To cut to the chase, I did unclamp everything and flip over the cradle and reclamp everything back together and begin the process of riveting the top side rivets to the LE skin, subskin, and ribs. In fact, I thought that this had gone just as well as I had thought that the bottom side had gone - perhaps even a bit better, now that I knew what to expect. I felt that way -  right up to the point that I shined the flashlight on the bottom most forward rivets attaching the subskin, outer skin, and ribs. If you have read the last 2 posts or so you will note that at one point I commented that I did have some difficulty with one of those most forward rivets, but at the time I did not know why, and I thought that I had overcome the problem eventually without doing any damage to anything in the process.

Well, when I viewed the shop heads of the forward rivets in that area, it become very apparent what had happened, and it was exactly what I had said all along that I absolutely could NOT do if  were to successfully complete the mod. In short, I discovered a crease on the subskin where the edge of my bucking bar had been digging into the subskin just beyond one of the most forward rivets on one side, so all the energy from the rivet gun was being passed through the bucking bar and into the subskin, which is why that one rivet would not set properly. My continued pounding with the gun only served to tighten the skin and stretch it a bit, which caused the outer skin to stretch a bit as well.

You can almost see it in the very last pic from my previous post by double clicking on it to make it larger and clearer, and look at the forward area next to the cut out in the outerskin along the one side. You can just see that the outer skin des not sit the same way against the subskin that the rest of area is, and that means that the outer skin has been stressed.

Here is a pic that I took, that, without even realizing it, captured the issue.

Look at the left side, just past the most forward nut plate on the bottom, and you will see what appears to be a whitish line. This is the crease that was hammered into the subskin. Remember to double click on the pic to make it larger. If the sides of my bucking bar had not been covered by duct tape I most certainly would have plowed the obviously incorrectly placed bucking bar right through the subskin and continued to pound into the outer skin. 

Finding this just about made me sick to my stomach, because this was precisely the thing that I feared the most that I knew I absolutely could not do. I now fear that the only way to correct this issue would be to completely remove all rivets, and remove and refabricate a new custom subskin. This is something that I absolutely will NOT do. I hate the fricking forward rivets just about more than anything I have ever hated in my whole life, and I will absolutely NOT start over to remanufacture a new custom subskin.

Right now I am waiting for a tech counselor visit to thoroughly inspect this damage and determine what to do next. Even if I am told to remove the subskin to effect a repair I don't think I will even do this. Instead, I am now prepared to order a new LE skin and perhaps new ribs to go with it, and rebuild the stock LE and completely abandon this idea so that I can hopefully have a flying airplane sometime before I leave this earth.

For anyone out there following - and I have said this before - if you are thinking about building then I strongly urge you to get the quick build wings and then you can decide if you want to do the quickbuild or slow build fuselage. The quickbuild wings will already have the LEs and fuel tanks completed by the factory - so you wont have to mess with ANY of those fricking forward-facing rivets. 

So I am pretty disgusted right now - but I still have fuel tanks to finish, so until I get a chance to talk with the TC about my latest blunder I will shift my focus to the fuel tanks once again. I  have discovered through this process of building a metal airplane that I absolutely hate riveting - so this will most definitely be the first and last time that I endeavor to build one. There is just too much aggravation involved for me. YMMV.