Thursday, May 31, 2012

Nose Leg Installed

In the morning Elizabeth and I managed to lift the fuselage off its work bench. It was about the maximum of weight I could manage and I was glad that I had to move it just a few feet to get it cleared and let it down.

After that I had another artistic episode. Remember my artsy fuel line bendings in the fuel line installation section? Well, this was even better! I could bend large sculptures free hand this time. I'm talking about the brake line installation.
The cutting and flaring part was harmless yet.

In deviation from the plans, I started bending the circular 360 degree bend around the brake calipers and the gear leg. After I had an idea how to get this done and I had an angle to follow the gear leg, I installed the opposite end in the tunnel. It needed a bend in there too to clear the gear leg hardware.

The left brake line was rather long and I had to add some curves to "burn" the excess length.

The same artistic bending procedure was done to the right side.

The cable ties and plastic tubes were added and tightened but that rather disturbs the otherwise nice looks. I moved on to mount the nose gear leg. 13 AN3 bolts had to get inserted and torqued. I started by adding two temporary AN3 bolts on the front of the firewall which helped keeping the leg in place while I was inserting the correct bolts from the bottom.

The work on the nose fork was a bit tricky because I wanted to avoid having to take this all apart again in section 36 when installing the wheel pants. So I looked ahead and figured out what changes they wanted me to make to the fork while generally following section 35.
The first step was to countersink nutplate attach holes and rivet the nutplates in place.

This was followed by more countersinking to rivet on the little plates on the inside of the fork. I also put the AN5 bolt and the stack of washers in place.

That's when I hit a road block in form of a missing tool. The plans asked for a 5/16"-24 tap and my toolkit obviously didn't contain that. It was 4pm and beginning rush hour so I held off on driving to the hardware store and instead built my HP shop crane for the engine installation.

It's in its folded configuration in this picture. I hope this will make the One-Man-Rotax-Installation easier.
Two hours later I drove to the store and got my tap and continued section 35.

I tapped the two holes and inserted the screws but my happiness about continuing was short lived. I hit another major roadblock. This time in the form of a missing part. I went through the inventory lists over and over and couldn't find a hint of it. U-611 the two disc springs were the pieces missing. I started to clean up the shop and after searching for more than an hour I finally found them. It was passed sunset at that point and there was no point in trying to finish the next step.
Instead I got everything ready for an early start in the morning. I packed the bronze bearing with AeroShell #22 grease and laid out all the necessary parts.

Wednesday, May 30, 2012

Two Legs Are On

Today was the day of the big move. The big move of the evolving fuselage from the patio to the carport. It was pretty tight - mainly due to the clutter that has collected in and around the corners. I won't say a lot and just let the pictures tell the story.

And that was it. Not too bad but I could have used another helping hand to push while I was pulling.
The next step was to put the fuselage on its belly again. Shifting the fuselage around on the work bench has gotten pretty tricky now as the weight is causing a lot of friction and one person is almost too little to move it now. I'm glad to have it on the wheels soon.

Unfortunately, the work bench is too wide to allow both legs to get installed. I had to pull the fuselage all out to a corner and cant it so the tip of the corner would sit underneath the gear leg tunnel. It took me about half an hour to move fuselage inch by inch into that position.

Then access was possible on both sides by just pulling the fuselage laterally a bit to clear the inboard access hatch to tighten the bolts. Here you see the inboard leg support on the left side.

That was fairly easy. The hard part was yet to come. I assembled the outboard leg support and greased the work plate before inserting it.

However, the "insertion" was the problematic part. At first it looked like it would go in.

Looks good, doesn't it? Look closely though. The rivet wart in the shadow of the bolt is right behind it. So close that I cannot turn the bolt head and pass the rivet with a nut or wrench.

This is a long known problem and has been extensively discussed on VAF. The rivet had to get drilled out which is easy if you have an angle drill or a long drill bit.
After this hurdle was passed the leg went in fairly easy.

Rinse and repeat on the other side. I had to drill out the obstructive rivet there too. On to the installation of the wheel axle. Note that in the following picture the axle is not installed right. The holes for the wheel pants are vertical and they have to be horizontal. I wish I had seen it then. Also note that the brake thingy is on with the groove in the knurled nut on the brake side. It should be on the wheel side though. I didn't find anything in the Matco documentation about the torque for these axle mounting screws, so I used the maximum of 140 inch pounds for AN4 bolts.
Almost forgot to mention that I also fixed an error I had committed earlier when preparing the gear leg section by assembling the tires. Back then I didn't care to read manual and assumed I needed automotive bearing grease for the main's bearings. I removed this grease, cleaned the bearings and re-packed them with AeroShell 22. This took quite a while. What is the approved and correct way of removing grease from bearings? I really created a mess with that and had this stuff all over me. Yuck!

A note in my builder's manual said at that point to check with section 36 before continuing. That's the section for the wheel pants and I wish I had put that note BEFORE the step I just completed. Section 36 revealed on page 36-05 that ....

... I had to unscrew those bolts I had just installed, throw out the washers under the bolt heads and install the U-00003's which are mounting points for the wheel pants.
I also installed the tire and the brake at that time on the left side. However, I would soon find out about the aforementioned mispositionings and undo all that again.

For an unknown reason everything went accidentally correct on the right side which I didn't take photos off to not bore you.
I had started at 9am and now it was passed sunset. Here you can see the current arrangement in the carport.

That was about the time when I noticed my mistake on the left axle. I just accepted fate and undid everything and turned the axle as well as that brake thingy, then fastened everything again.

I am not sure if I tightened the axle nut correctly and left the cotter pin disengaged, just as a straight pin. The wheels need a lot of force to turn right now but reading the manual that seems to be correct. I will research this issue and then decide what to do about the cotter pin. Maybe I wait until certification before really engaging it.

Now I have to find out how to get the even heavier thing off the work bench tomorrow. I hope ELizabeth will have a moment to assist me with this. I wonder what the fuselage will do on two legs. Is the CG in front of the wheels or aft of it? I bet it's aft and that would help with the nose wheel installation too.

Tuesday, May 29, 2012

A Broken Servo

It was indeed a broken servo that caused all those problems I had encountered before when first testing my avionics. The new one arrived today. The left one is the "new" one - remanufactured that is. That's why it has a serial number lower than the one I had bought from Van's. The left one in the picture is the replacement unit, the right one is the broken one.

I crimped the connectors on and hooked it up to the bus, without installing it yet.

I first booted the avionics without external power, just using the battery. Everything worked fine (remember, before the swap, the fact that the servo was attached to the bus made the EMS and ADAHRS disappear) and I powered the system up with the external power supply. Switching the AP on, didn't cause any problems. Hardware detection showed an additional servo that needed a firmware upgrade. So I did that and then the system showed all 5 devices as operational.

Great! I faked some servo calibrations and confirmed the new unit was working correctly before installing it back in place.

Excellent! Everything is now working as it should have about 25 work hours ago. At least the problem is fixed. All that was left to do was to clean up the wiring, put the backshells back on and hook everything up to the Control Module again.

Then I attached the rudder cables temporarily to the rudder pedals as part of section 32. This is the last thing to do before I wanted to turn the fuselage back on its belly to attach the gear legs.
That means that tomorrow I will clear the carport and move the fuselage out of the backyard.

By the way, I am very amazed that the SkyView system, running two separate network buses, can be so easily confused by an erroneously acting servo. And get so badly confused that it would have been of no help in providing the pilot with essential data to fly the plane. This experience just confirmed that it was a very good decision to plan for analog ASI and ALT devices.

Sunday, May 27, 2012

Floor Panel Modified

Before working on the floor panel I finished the bulkhead back support angle. It needed the nutplate attach holes drilled and dimpled as well as the screw holes dimpled.
I did all put the corner hole which will get a one lug nutplate of which I don't have a sample here, so I have to wait until I get the actual nutplate.

Then I focused on the floor panel. I thought it through for a while and then decided against repositioning the drill markings. Lining up the screw holes would have created clearance issues with the back support and the closest flange.

The little angle you see is one of the tabs of the wing ribs we had to saw off. It has 4 evenly space holes in it and I used it as a drill template and as a stiffener for the back plate.
I separated the panel using the fine hack saw and for about an inch the sole saw blade again.

Drilling the nutplate attach holes and dimpling all the holes in the back plate was up next.

I had 6 of the countersunk K1100-08 nutplates in stock. With this amount I could have riveted the large angle for the bulkhead or the floor panel support. With the one missing nutplate type for the bulkead angle I decided to finish the floor plate as I would not be able to finish the big angle anyway.
So I riveted the three nutplates for the floor panel in.

Then I attached the backplate to the floor panel piece, using AD4-4 rivets.

Here you can see how I applied the angle. The riveted piece is much stiffer than the floor panel itself. I think this modification actually increases the structural stiffness.

This completed the floor plate mod. Outside I was spraying some primer on the bulkhead back support as it has time to dry sufficiently and bond to the metal while I am waiting for my order of nutplates to arrive.

I am running out of work at this point as I am waiting for the servo to finish the avionics installation before I can move the fuselage outside into the carport and continue the gear leg section. One of the few things to do was to install the power supply for the PCAS. After some thinking I decided to install the breaker the install kit came with. I will run the unit off of the GPS/ADSB power supply and I don't want to lose my backup GPS if the PCAS would have a tripping fuse. Here's how the panel looks like now.

Of course I will remove this breaker before certification and just put a matte black sticker over the hole. But at least I can set up as much of the add-on wiring for now and reduce the amount of work after certification. I am not completely done with the hook-up and will finish this tomorrow.
I'm pretty much out of work at this point without having the servo. I could just assume that it really was the culprit but I rather verify that before closing anything up.
Maybe I could look into the cockpit light installation and close section 40. I'm sure I'll find something to do ...