Battery Box Problem - Anyone Else?

When you get to the firewall, you have to beware. I've been finding more and more plans errors lately as I'm moving ahead. If there is anyone up to the same spot I am, I am unlikely to be the only one with this issue. If you also have this issue, I'm hoping to join up with you and share the cost of some parts to repair it.

Let me explain:

In the plans, there are many areas on the stainless firewall that they tell you "DO NOT DIMPLE". There are also areas on the underlying support aluminum that they tell you "DO NOT COUNTERSINK".

The battery box gets riveted on to the forward side of the firewall using countersunk rivets. The INTENTION is to countersink the battery box and rivet it to the firewall. The reality, in the current version of plans, is that you end up dimpling all those holes in the firewall, and countersinking the aluminum supports under them. So, now you'll end up with a battery box that is laid on top of countersunk/dimpled holes...creating a gap, and then you countersink the battery box for the actual AN426AD4 rivet.

So, DO NOT DIMPLE OR COUNTERSINK the holes for the battery box as the plans tell you.

I emailed Van's support after finding this all out the hard way, and after a few days I finally got a reply that I didn't really like. It wasn't discussed with engineering...just off the cuff. The suggestion was to just rivet those dimpled holes with nothing in them, but then move the battery box over and re-drill new holes. The firewall supports being somewhat structural, I wouldn't do this without engineering blessing, but beyond that, now your battery box location is shifted and who knows what may be affected later on.
From the discussions I've had with tech support, it sounds like they are highly unfamiliar with the kit thus far, as you'd expect, because they need to learn as they go just like we do. Only engineering knows the intention, or structural concerns, so any RV-14 specific questions need deeper investigation by them until they learn it too.

I did find a better fix. Genuine Aircraft Hardware sells some Countersunk Repair Washers/Plugs, p/n LS5931A71, that are designed to go into a countersunk hole if you later need to cover it with a flat material or a round head rivet. It's a cone-shaped filler. It would fix the issue nicely.

The only catch is, they are sold in 100 packs only, at about $56 per pack plus shipping. We only need 19 to fix a battery box. If there are enough of you out there who have dimpled this area, then I'll consider ordering a 100 count pack of them and splitting it up. This being the real fix, it would be good to do, but at almost 1/2 the cost of a new battery I don't want to swallow it all alone if I don't have to.

Anyone else up to this stage with the same issue?

Tim

Firewall-Battery Box

TimO said:

I did find a better fix. Genuine Aircraft Hardware sells some Countersunk Repair Washers/Plugs, p/n LS5931A71, that are designed to go into a countersunk hole if you later need to cover it with a flat material or a round head rivet. It's a cone-shaped filler. It would fix the issue nicely.

The only catch is, they are sold in 100 packs only, at about $56 per pack plus shipping. We only need 19 to fix a battery box. If there are enough of you out there who have dimpled this area, then I'll consider ordering a 100 count pack of them and splitting it up. This being the real fix, it would be good to do, but at almost 1/2 the cost of a new battery I don't want to swallow it all alone if I don't have to.

Anyone else up to this stage with the same issue?

Tim

Click to expand...

Yes, just got off the phone with Van's, their solution is to use a hammer or rivet gun and bang out the dimples. I will go in with you Tim if that is a better solution. PM me. Thanks.

Thanks for the heads up Tim, I started on the firewall last evening but have not got to dimpling yet. First task this evening so I will be on the lookout.
Ron

Yeah, that bang out the dimples solution would be ok, if it were just the firewall stainless...but once you countersink those aluminum angles under them....then it's too late for that.

Right now I'm planning to order the 100 pack. I'm not sure how many people there will be to split them with. Sure would be nice if I didn't have to shoulder the whole $56+shipping is all. For $25 I'd not worry so much.

My other consideration was to JB weld fill the holes, then re-drill, but I doubt JB weld would have the tensile strength to not deform when you hammer the rivet.

A 3rd option I'm going to quick test tonight is to see if I can create these washers by undersize drilling through an AN426AD4 rivet, then use a reamer to ream it out to #30 or #31 without too many burrs. Once you hit that size, the stem would fall off, leaving you with a washer just like what we'd buy. The catch is, can you drill and create one that fills the void as nicely as the washer that's meant for the task.

Being an aerobatic plane for me, and a trainer plane for my daughters, I'm not sacrificing on anything that could be structural.

Tim
I wish I had read this half an hour ago! I think that a counter sunk .063 strip over those dimples on the cabin side might just do the trick. I will take a look at it after lunch and report back.
Thanks for the heads up!

Well, if you end up wanting the washers, let me know. If I buy 100, I don't want to be stuck with them all.

Tim

A plans revision/correction for this error is in the works right now.
The three prototype fuselages built so far were done with these holes not dimpled, so that was always the intent, but some how the grid area marking "do not dimple" these rivets got left off the final release version of the plans.

Tim, you mention in your initial post "I've been finding more and more plans errors lately".
I have only seen one other post by you recently regarding a plans error, but you apparently deleted it because it is no longer visible (I assume you found it was not an error after all?).
Are there others that you would like to mention?

My recommended fix -
The battery box is .050 thick. This is thicker than what is recommended for dimpling, but it is one of the few parts made from 6061-T6 instead of 2024-T3, so it is a bit softer / more malleable than 2024-T3.
Because of that, it should dimple countersink just fine as long as you use a c-frame tool / hammer. It will require a slightly modified #30 male dimple die to allow for the bend radius in the box

Scott Mc

Here is my fix for the issue. I took a piece of .063 angle and cut one side of it off to make a piece of flat stock that is the right width. The initial radius on the angle nestles nicely with inside of the firewall angle.
The length is just over four rivets long on the firewall. Although only two rivets are affected going an extra two rivets long is a bit of belts and suspenders.
The angle weighs 6 grams so I do not think this weight penalty will be too much to bear.
I back drilled it in place to get the proper fit and I am sure that this will solve the problem. The area is likely stronger now then it would have been if the initial cross piece had not been countersunk by mistake.

Yes, you are correct, there are more holes that are affected but the two that I showed in the picture are related to the firewall stiffener that is already countersunk.
What I will do for the other holes is to use some 3/4 .063 angle and match drill them to the holes that are dimpled. Countersinking the angle will look after the dimples in the firewall. These angles may just be handy later on for mounting things aft of the firewall.
I will wait until I get the larger cross pieces on the firewall before I make these extra angle pictures. If I get to it tomorrow I will post a picture.

This is a great kit and these little issues are part of the fun of being some of the first to go through these steps. I will pay a bit more attention now and read ahead a bit more then I have with the other parts of the aircraft.

Regarding the fix, I think that a dimple, although it may work, will probably not be very crisp in metal that thick, so the best fix is the fix that would be done using the proper hardware. I don't think that just putting the doubler on the inside of the plane is enough. You're still leaving a void area along that rivet, where you won't have any material, or support around the rivet shaft. It will probably hold fine, but rivets are designed to be driven and expand and fill the space and hold the material around it. So doublers on the inside don't do anything to accomplish that goal.

If you look at these parts:
http://www.gen-aircraft-hardware.com/images/pdf/CSK-repair_washers.pdf
and do a bit of reading, this is a hardware method that is actually designed to fix situations like this. If you want to lay a flat sheet over a dimple, and fill the void, you use these washers. Part number LS5391A71 does the task and in my opinion, after reading enough pages, is the actual MilSpec and approved type method of doing the quick repair. It's just a form fit filler washer that brings that back up into a flat surface. Easy, with no other real issues or impact. The only downside is the price. $55.80/100 from Gen-aircraft-hardware.com. But, if you think that's bad, I called places and got quotes from aviation hardware places that had stock yesterday. One place, sent me an official quote for $270/100. yes, that's right...trying to bend you over so bad that you'd actually pay $2.70 each for those little suckers. I called another place that had 46 in stock, thinking I could get only 19 that I wanted. They wanted over $5/each...I laughed in his face and told him they're .558/each from another vendor and he dropped it to $1.65. Still, that's insane.

So, I thought I'd try to see how I could manage in making them myself.
I took an AN426AD4-4 rivet, drilled a centered #35 hole in the middle, well down into the stem. Then used a reamer (either #31 or #30) to ream down into the rivet until the head popped off. This head, I then stuck in the hole, and sure enough, it fit great. It fills the void, and makes the material flat again. So rather than spend the money, I'm just going to hack up 19 of those rivets. I have photos that I'll post on my site on a later date.

Regarding the plans errors, yeah, I've found a few lately in sections 28 and 29, and some before that. Generally I either A) email Van's right from the garage and just let them know, or B) try to remember to email it in later. I don't like web forums in general because I don't reliably ever have time to visit them. Email based forums work much better for me. Unfortunately for the RV-14 there is none, and this battery box issue was going to be a big pain for a lot of people if I didn't bring it up, so I did.

On 11/28 I told Van's about the battery box, and another issue. Page 28-11 there are 2 rivets on the far left of figure 2 that are called out as AN470AD3-3 rivets, which is ok except in all the other places and that place we dimple the holes in the rib underneath. An AN470 would be much easier to install in that location, but since it's already dimpled, you're forced to do an AN426. Nobody got back to me on the battery box until 12/3, so I posted it here.

Page 29-05 I sent them a note that the VA-146's call to final drill #30, but they say AN470AD3-6 rivet...obviously an AD4 instead is what you need. No big deal.

The issue I posted and pulled the other day is Page 29-07, the F-01444A-L doubler. I wanted to be absolutely sure which part was the "R" and which was the "L" because although I could be 70% sure, a little hint on the plans would have helped a lot. Tech didn't know, but engineering confirmed that the bent edge of F-1444A-L faces AWAY from the part. But, I also had posted that we were missing the 12 CR3213-4-05 rivets that are in the plans. After talking to tech support though, I was told that they prefer I *not* post things on the forum first, but rather call. So I yanked the posting.
Incidentally, a couple days later I hear you're all going to be getting the CR3213-4-05 rivets that you need.

That's the last week or so worth of things I ran into. There have been a few questionable rivet length choices along the way, but I don't bring those up...just put in the one that works best and move on. So most of the things I find, if they're significant at all, I just shoot Van's the email. If I'm at home I'm likely in the garage, pounding rivets, not surfing the web. I'm finding that building goes much faster the more I keep my head in the project, and I want to see the finish kit arrive in early 2015 so that I can have this thing painted and completed by May/June if possible and I get my garage back next fall.

Don't get me wrong...for the most part, the kit is fantastic. I can't believe the engineers are so good that I can build some of these sections and join them with such precision. They think of everything. The occasional wrong rivet callout or missing part isn't that big of a problem. If anything, the biggest fault I'm finding is that perhaps Van's is trying to do TOO MUCH in the RV14...leaving less flexibility to the builder. When it comes to cutting the panel for my avionics, and doing the Throttle quadrant, I get the feeling that I'm going to have a good sized modification job ahead.

The RV-10 was much easier to customize, to just be given a big flat space.

Tim

TimO said:

The issue I posted and pulled the other day is Page 29-07, the F-01444A-L doubler. I wanted to be absolutely sure which part was the "R" and which was the "L" because although I could be 70% sure, a little hint on the plans would have helped a lot. Tech didn't know, but engineering confirmed that the bent edge of F-1444A-L faces AWAY from the part.

Click to expand...

Thanks Tim.

Crisp dimples on the battery box are not really needed. All the rivets will be hidden when the battery is installed, and the slightly less than perfect dimple will have zero effect on how flush the rivet is.
This was actually considered for the installation but since the B.Box is more than thick enough, machine countersinking got rid of the other dimpling and countersinking steps required.

All of the other errors you mentioned (and a few other very minor ones you didn't mention) are already known and will be correct soon in a plans update.

The one I quoted above is actually covered. If you look closely at Figure 2 on Page 29-07. It identifies which part is left and right... orientation can be established by the view of the flanges (shown facing you as you look at the figure).

Thanks again.

I am not really sure what the material is that the battery box is made from. It seems a bit softer. Thickness is close to .050. Interestingly I weighed the box vs. the old metal box and it was about 400 grams lighter, almost a FULL pound lighter!
The good news is that it dimpled quite nicely and thus solves the issue for those like myself, that had dimpled the firewall. I think that the dimple will actually be stronger then countersinking the battery box.

Tom Martin said:

I am not really sure what the material is that the battery box is made from. It seems a bit softer. Thickness is close to .050.

The good news is that it dimpled quite nicely and thus solves the issue for those like myself, that had dimpled the firewall.

Click to expand...

Tom,
In my previous post, I mentioned that that battery box was made out of .050 thick, 6061-T6.
I pointed out that it was softer material than 2024-T3 and that it should dimple countersink just fine. That is why I recommended that any builder that found them self caught by this plans error, should just dimple the rivet holes in the battery box.

Glad to hear that process did indeed work fine.

Scott, yes I see your prior post, and I am not sure why I missed it. My experience countersinking softer material has not always been good. The bottom holes on the tray are going to be tricky to do as the front lip of the box will make it hard to use a countersink tool, machine or by hand.
The material dimpled quite nicely and I believe that just might be the best method for mounting this part.
And can I say it again? "almost one pound lighter!!"