Wear Plates Primed

Not much to report from tonight's session. As planned, I prepped and primed the wear plates and the associated aluminum buffers.


The following reassembly of the gear legs might have to wait till the weekend.

Wear Plates Countersunk

It is a long time since I last had a job that I could do in my shop and tonight I could do one again. The steel wear plates had to be countersunk (on their bottom side!). A few weeks ago I had already ordered the 1/2" die with a 1/4" pilot and I could finally put it to use.


This was after the first one was done.


And here the set is complete. The nice thing about countersinking steel is that you can hardly go too deep by accident.
It was already dark when I was done and so I planned to prime the aluminum and steel parts tomorrow after work.

6" Drill Bits Arrived

The 6" drill bits from Avery Tools arrived today and I got right to work on the plane when I came home from the paying job and found the parcel.


The reflection of the drill bit on the template surface really helped getting the holes drilled straight. However, I cannot understand why Van's was so cheap to just provide one template for two sides. I ended up having remove those nuts holding the template over and over to swap the template from one side to the other and then back again for drilling the 1/4" holes. Come on, really, Van's?


Here you see the right side after opening up the pre-drilled holes to 1/4". After that the template has to get switched back to the left side as you need the reflection to ensure a perpendicular drill bit.

Finally, the chips were removed and the two mount assemblies were removed from the plane, while making sure that they stayed aligned as they were drilled to get marked clearly for reassembly. Also, I deburred the freshly drilled holes. The drill bits are really high quality and there were hardly any noticeable burrs to remove.


The sun had set by then and I called it a day after another 1.5 hours. So far, I have spent 25 hours working on this SB.

Snow in Tucson

What a freak event! The last time I saw it snowing in Tucson was in 2006 and the kids were dancing in the streets and most of them had never seen it snowing before. Today was much worse than that.



This has certainly nothing to do with the build at all. I cannot even use this as an excuse for not building today as I was waiting for the medium length drill bits. However, I thought, it might give Dave a chuckle to see what *horrible* weather conditions I have to work in.
Well, at 76F on the weekend (3 days ago) I was working on the plane in shorts and T, and now wild horses couldn't get me out there for good.

6" #30 Drill Bit Needed

I am glad that I got to work on the plane to night, as this could possibly safe me some valuable time waiting for new tools to arrive. I put together the new set of bolts, brackets and wear plates on the left side, to see how accessible the template and its holes would be for match-drilling. As it is imperative that the drill bit would be aligned perpendicular during the drill process to ensure a straight hole for the bolts, I also wanted to see how well the reflection of the drill bit on the template could be used to ensure that.
Putting the assembly together was the easy part, although it could help to have a second pair of hands for this.




It turned out that none of my drill bits would actually get the job done. The problem is that a 12" long drill bit is almost touching the back rest and wouldn't allow to attach a drill to it. And the short jobber bit wouldn't work because the chuck of the drill would be interfering with the side of the U-section. I measured and calculated and came up with a 6" bit to be perfect. I ordered one in #30 and one in 1/4", so opening up the match-drilled #30 hole would not get further delayed. I could probably get a usable 1/4" bit from a hardware store (or I might even have one in my toolbox ) but the shipping for just one drill bit is more than 200% of the bit's value and so I just added another one to it.

I hope the bits arrive before the weekend...

Doublers Riveted

Today was the second attempt at dealing with the CherryMax^® rivets. This turned out to be not all so bad as yesterday. I started with riveting the 1202-T and -U angles to the U-section. This time I started the outer rivets from the belly side. As you can see, they were properly pulled this time.


Access with the manual riveter to the front rivet was easy but the aft one was a real challenge. I needed all the wiggle room I could get and had to cant the rivet stem when extending the riveter's arm to get a grip for the next pull.


A riveter with a much longer head would be desirable for this job. The rest of the job was quite uneventful and business as usual. Here's a shot from half time riveting the doublers to the right side skin.


And shortly thereafter the riveting part of the job was done.


With a coarse grinding wheel I beveled the edges of the landing gear attach brackets.


Here you see both finished brackets among some workbench clutter.


The next step is to match drill additional holes into the U-section for additional bolts to be added to hold the gear legs. This is a job where I will just get one try, hit or miss, so I decided to postpone that work to a day when I'm fresh.
So far I've spent 22.5 hours on the SB.

Beware of the CherryMax®!

CherryMax^® rivets that is. This pull-style rivet looks so familiar but behaves to differently and is very unforgiving - but I'll get to that in a moment.

I had worked on the SB during the week as much as I could (which wasn't all that much, but at least I worked on it). So, I had done all the deburring of the side skin doubler and the newly drilled holes. I've also managed to prime the doublers on one side. When I removed the vinyl on one of the large doublers, I've noticed that it some light corrosion which I also removed and sprayed over with primer. That should last until the plane gets painted.
When I sprayed the primer it was already dark and pretty cold too, so I used two halogen lamps to heat up the metal and expedite the curing process. That where the yellowish tint in the following picture is coming from.


Yesterday then was the big work day where I had planned to put all the doublers in place and rivet them on. First I cleaned the U-Section to put the now two skin attach angles in place, using these fancy CherryMax^® rivets.


I tapped the wing bolt bushing out a bit more to see how I could get access to the rivet for riveting. I chose the forward-most position as an example as this one appeared to be the trickiest one to get to.


You can see the stripped down riveter in the upper right side of the picture. It appeared that it was a close call but possible to get to the rivet and pull it straight. As a spoiler, and to avoid that you're making the same mistake, let me tell you right here, that it was not good enough. And that includes the aft=most position as well. Do not follow my example and rivet those from below.
The angle was put in place, clecoed and rivets where inserted.


Now, to my own defense, I have to say that I did indeed read the notes about how to install CherryMax^® rivets and how important it was that the stem was not tilted while pulling. I can just guess that pulling 20,000 LP4-3 rivets that don't give a damn about the angle of pull, might have given me a callous attitude towards sensing such a tilt.
To me the access to the rivet appeared to be perfectly ok and so I riveted the angles in place


Pulling these rivets feels different than LP4-3, so I didn't know what to make of the sensations I felt in my hand and the unusual sounds I heard. First I thought, it was much easier than I thought it would be and then I looked at the heads. If you look closely, you can see that the stem left a hole in the head on the foremost rivet. The center two do not show that hole. An inspection from below confirmed my fears:

.
The stems of the aft and front rivets had not pulled in sufficiently and the stem broke prematurely! I decided to try to drill out the rivets, following Van's note about CherryMax^® rivets. While drilling into the stem of the first rivet using a #40 angle drill bit, something felt odd and I pulled the drill out. Oh no!


The drill bit had broken off inside the stem and the piece was stuck in the head. There was no way for me to remove the rivet now, without causing serious damage to this delicate area. I decided against further experiments and instead chose to add two more holes to the angles and the U-section. (I might decide to use a rivet gun on the two stems that have not seated properly to improve the rivet strength but I first have to get one.)


Now being away from the sides of the U-section, the access was definitely easier and the riveter worked as it should.


The rest of this ordeal went much smoother after this CherryMax^® rivet episode. The usual CS4-4 and LP4-3 were no problem at all, also the ChreeyMax out the skins were no issue as they were all easily accessible.



That concluded Saturday's work.
Sunday started with the removal of the 1202T angle in the U-section on the right side. This one was much tougher as the ELT bracket is very much in the way of any operation you would like to perform in this area.
The angle drill and thanks to some Yoga lessons helped in getting the job done right.


With the experience from the left side, drilling out those rivets on the right side was a quick job. Note that I clecoed the skin while removing rivets to give it a bit of support.


Match-drilling and deburring went along and soon the skin was ready to receive the doublers.


The doublers were scuffed and primed and dried in the warm sun (76 degF today!).


Right at sunset I finished clecoing the doublers in place for the riveting action to come.

Landing Gear is Off

My shop day started chilly temps down in the lower 40s and I decided to utilize the propane heater for my second day working on the Landing Gear SB. Thanks to calm to no wind conditions, the heater worked pretty well in the open car port. In just 45 minutes the first leg was off.

The only part of the landing gear that remains inside the tunnel, is the inboard mounting block that also connects to the brake line. I put a paper towel under the brake line fitting, to catch any drops of brake fluid coming out of it.

The right leg was up for removal next.

This one gave me some grief as the outboard mounting block could not get removed without drilling out the infamous rivet again that keeps that block from easily sliding in and out the tunnel. Eventually, after 45 minutes again, the leg was removed and stored.

The part in the instructions about what parts of the removed landing gear hardware we are supposed to retain was text only and, me being a visual person, I needed a while to look up the drawings in the landing gear section to identify what they were. As a short-cut here is a picture of the hardware for one side.

It consists of the two nuts of the outboard bolts (the washers were not mentioned, but I wonder why, so I threw them in anyway), the outboard mounting bracket and the inboard wear plate.

A closer look at the washers showed some odd deformation on two of them. You can see it best on the washer in the center of the following picture.

This indicates some very small stress points and I cannot figure where this was coming from. This landing gear wasn't even in use yet, so I can really see how this could cause some stress related fatigue and failure on the U-section where this washer was located.

Next step was to mark the side skins to highlight the region where rivets had to be removed.

I drilled out all the rivets inside the marked area on the left side. And pushed out any stubborn stems that didn't want to just fall out. The 4 rivets in the U-Section that attach the stiffener for the side skin were most awkward to get to. The recommended 12x#30 drill bit is way too long to get to them and the jobber bit is too short. I ended up using my rivet remover kit that is about 6" long. This will be even trickier on the right side as the ELT bracket will prevent me from using even that 6" long bit. I anticipate hacing to use the angle drill there but I haven't tried yet.

Then the doublers were deburred and clecoed onto the side skins. Some 50 something holes of drilling later, the side skin was perforated as requested and it looked like a cleco hedgehog.

Before I removed these doublers, I match-drilled the new 1202U side skin stiffener which will go on the upper side of the U-Section (in addition to 1202T, the one on the lower side). This stiffener combo is a bit weird as the SB kit comes with a replacement 1202T that looks pretty much like the 1202T that I just removed from the plane. I cannot see that the material of the new 1202T was any thicker or different from the old one.

I assume we will be asked to discard the old one and I will surely install the new 1202T, I just would like to understand what the difference is.

Next, all the doublers and clecos came off again and the holes and parts were deburred. They are ready for riveting now and I think I'll prime them before that. These doublers will be in an area where they could easily collect moisture and grow corrosion without noticing.
This was the time when daylight was getting scarce and I called it a day. I'm now 9 hours into the SB and close to halfway done with it.

During the week I plan to throw some hours in for prep work. I need to prep the doublers for priming and prime them, and I think U should be able to do some of the drilling out of rivets during one evening as well.

Starting the SB - for real

Tonight I started to seriously work on the landing gear Service Bulletin. Finally!
The trick to fool myself is real simple. All I have to do is to convince myself that I go out in the shop and vow to complete one single step. The single step I had avoided for so long was to drain the brake fluid.

That's really all it took.
I drained both calipers at the same time and helped it by pumping the brakes manually (meaning: with my hands, not sitting in the sawhorse-supported fuselage).
The system cannot drain completely without blowing air into it from the reservoir level but I think Van's did not mean the 'drain system completely' instruction literally.

So, after I had completed this little step, I felt like I couldn't just walk away after so little time put in - and now that I'm here, why not do the next step, and the next, and the next. That's how it worked for me, until it really was too dark to continue and the next step being a bit too much for a short evening.

I disconnected the outer brake lines in preparation of removing the gear legs and measured and marked the drill spots on the belly skin to allow for easier access to the outboard landing gear bolts.

I punched and pre-drilled the four holes and opened up the holes with the step drill to 3/8" diameter and deburred the inside of the holes.

As the cockpit area is currently covered with a tarp I decided to delay the removal of the outboard cushion clamps until I have access to the U-section anyway. The following step was to remove the gear legs and that was a bit too much for a short evening. At least, I got to see a beautiful sunset before closing up shop.