Worked on Cabin Frame

I rounded over the edges of the canopy frame joint strips.  These join the front and back halves of the cabin frame.  The radius is necessary so that the halves can be pulled tightly together.

I also put a strip of masking tape around the inside edge and marked for the lowest hole.  I’ll use a rivet fan to lay out holes along this strip and then use it to drill the holes evenly along the inside edge of the canopy frame.

Misc Engine Tasks

I received another order from Aircraft Spruce today with this AN816-4D fitting that is used to tie the manifold pressure line into the #3 cylinder.  The end is taped off with electrical tape to keep moisture out of the cylinder until the manifold pressure line is installed.

The order also contained some all-metal lock nuts, so I used a few to install some adel clamps on the starter cable wire.  In this picture you can see an adel clamp holding the wire to the oil pan just above and behind the mixture bellcrank.  After that, the line drops down…

…and run through these adel clamps on its way to the starter solenoid.  After everything was tightened down, I removed the terminal from the starter so that I wouldn’t inadvertently turn over the engine during future wiring.  It will probably not be reinstalled until just before first engine start.

Finally, I clamped the engine ground wire where it passes by the upper engine mount tube.  This was a fairly long wire (read heavy under high g loads), so I didn’t want it to be entirely supported by the terminals on the end.

Manifold Pressure Lines, Cabin Frame Joint

An order from Aircraft Spruce showed up today with some 1/4″ ID tygon tubing.  I cut a short piece to connect one outlet of the pressure transducer manifold port to the Dynon manifold pressure sensor.

I used the remaining tubing to connect to the other outlet and ran this through the firewall passthrough.  Inside the fuselage, I’ll transition from 1/4″ ID tubing to 1/8″ ID tubing for the connection to the Lightspeed electronic ignition.

Finally, I fabricated the splice plates for the cabin frame halves.  The pieces that Vans provided for this were not square.  The two short edges were not perpendicular to the long edges.  I laid the holes out square though since the rivets will be seen on the outside of the cabin frame.

Started Cabin Frame

I called Bonaco this morning and put in an order for a few hoses.  I ordered a short hose that will run from the fuel bulkhead on the firewall to the inlet of the engine driven pump.  I also ordered the hose that run from the outlet of the engine driven pump to the fuel servo.  This hose needed 45º fittings on each end with 270º clocking.  We’ll see soon if I measured correctly.  I also picked up the hoses that run from the brake fluid reservoir down to the master cylinders.  Since all of my other brake components are black, I had Brett do these in black as well.  Finally, I ordered the brake lines that go from the bulkhead fittings on the firewall down to the wheel cylinders.  Van’s plans call for rigid lines from the bulkheads down to the wheel cylinders with generous service loops inside the wheel pants to allow for flex and vibration.  This is a notorious source of cracking though due to flex in the aluminum line.  Since aluminum doesn’t have a fatigue limit, even minor flexing will eventually result in failure.  Even the MIL-PRF-83282D brake fluid (which is a huge improvement over the old MIL-H-5606 fluid) is flammable, so a brake line failure can really ruin your day.  Some people run rigid tubing down the leg and transition to flex line near the wheel cylinder, but the whole gear leg flexes when on the ground, so this really doesn’t eliminate the line flex.

Since I’m waiting on an order from Aircraft Spruce for new 5052 brake lines, I decided to get started on the cabin frame.  I clamped a straight edge to the bench and then clamped wooden blocks to the vertical legs to define the overall width of the frame.

The center seam was pretty close, but I touched it up with the vixen file to get the edges perfectly aligned.

The bottom edges were not even close to parallel with the guide angle, so I marked and trimmed them flush.

Here is the result.  It looks like there is a shadow here, but that’s just the black line I drew parallel with the guide angle.

The canopy frame is about 1/16″ taller than the plans specify, but I’m going to leave this.  In fact, I’ll likely try to cheat the canopy up another 1/4″ or more in final fitting.  This will directly translate to more headroom in the plane which I’ve heard is a problem for someone my size.

Last up tonight, I drilled the 1.5″ holes in the bottom end of the aft members the roll bar.  This is to allow access to the bolts that hold the cabin frame down to the seat back support.


Trimmed Forward Spar Cover Attach Angles

Happy Father’s Day everybody!

I spent most of the day with family and some friends, but had a little chance to get out into the garage late tonight.  First up, I marked and cutout the notches in the outboard forward spar cover attach angles.

Next, I decided to try and bend the fuel lines that come in from the sides of the fuselage and connect to the fuel selector.  I knew I shouldn’t have started something like this at 11:30 at night.  I got the first piece mostly bent, then realized that I put one of the lines on the wrong mark on the bender and left one leg too long.  Attempting to fix it only fucked up the tube enough that I couldn’t get a sleeve to slide over it anymore.  I then took the only remaining piece of tubing I had and tried again.  After carefully measuring the bends, I proceeded to put one of the lines on the wrong god dammed mark on the bender again and left a different leg too long.  Holy fucking christ!  I was pretty pissed off by now.  I’m out of tubing and it’s expensive as shit to ship these 6′ long pieces from Aircraft Spruce.  I don’t want to order just one piece either, because what’s the chance that I’ll bend the next two perfectly.  So this was probably a $50 fuck up tonight just because I was not thinking clearly.  I’m going to bed…

Riveted Spar Cover Attach Angles

I blind riveted the attach angles to the gear webs using LP4-3 rivets.  I had to grind down the tips of the rivets and pull them in small steps (pounding the rivets further in each time).

I also installed the nutplates using MK-319-BS rivets since there wasn’t enough room to get a normal rivet squeezer in here after riveting these to the gear webs (and the nutplates couldn’t be installed first since they would have interfered with squeezing the LP4-3 rivets).  I just realized that I forgot to cut the notch in these for the fuel line grommet.  I’ll have to do that in place.

Installed New Mixture Arm

The shorter mixture arm arrived from Precision Airmotive today.  I installed it and then spent a little time adjusting the various linkages to get proper movement.  Here is the linkage in the idle cutoff position.

And here it is in the full rich position.  The shorter throw meant I could easily go stop to stop at the mixture arm.  With the longer arm, I could either hit one stop or the other, but not both.

Here you can sort of see that there is plenty of clearance between the mixture arm and the starter now.  At its closest, there is at least 1/4″ between these two.  Since all of this is rigidly mounted to the engine, this is plenty to ensure that these will never make contact.

More Work on Forward Covers and Fuel Selector

I put the forward spar covers in place.  These are supposed to fit under the front edge of the seat pan, but I put it on top initially so that I could match drill the seat pan to one hole in the forward spar cover.

Here’s a closeup of the hole that needs to be drilled.  A nutplate will mount on the spar cover and a screw will go through the seat pan and into this nutplate.  If I put the spar cover behind the seat pan, I’d be drilling this hole blind.

After match drilling those holes (one per side), I installed the nutplates and reinstalled the covers.  Next, I cut the flange off of the fuel selector mounting plate flush with the forward face of the fuel valve cover and cut a notch in the bottom of the fuel valve cover so that it could temporarily sit over the fuel pump.  I then took the fuel pump top cover that Van’s sells for the Airflow Performance fuel pump kit and figured out how low I could mount it.  Since the Andair pump kit is significantly smaller than the Airflow Performance pump kit, I had previously decided to lower the cover as much as possible.  This will require fabricating custom side pieces, but that’s pretty easy.

After determining the mounting point, I drilled the fuel pump cover to the fuel selector cover.

After enlarging the opening in the bottom of the fuel selector cover, I fit the flange from the fuel pump cover inside the fuel selector cover.  These holes will get dimpled and these pieces will be riveted together along with the side covers I need to fabricate.

Aft Top Skin

My buddy Andre stopped by today and prepped the aft top skin for riveting.  We didn’t have time to get it riveted, but it’s clecoed on and ready to go for next time.

While he was working on that, I moved the tee in the static system up near the top of the bulkhead, right next to where one of the stringers will be installed.  Since I decided to mount my ADAHRS from the top rib between F-706 and F-707, I decided it would be simpler to run the static tubing along that top stringer and directly into the back of the ADAHRS.  This has the advantage that the static ports are the lowest portion of this part of the static system, so in theory it should allow water to drain out of the system and not make its way into any of the instruments.

I also worked on the forward half of the center cover.  I’ve enlarged the hole at the back half for the fuel line to drop through.  I’ll still need to enlarge it a little more to ensure it can never come in contact with the fuel line and abrade it.