Locating the Oil Cooler

While I was thinking about the aileron control cables, I realized that my previous location for headset jacks wasn’t going to work. I cut the old bracket off and this is what was left:

Headset Bracket Weld Bead

Headset Bracket Weld Bead

I used the die grinder and files to clean off the weld bead. It’s always frustrating when I end up making more work for myself, but such is the nature of building my own airplane I guess. I picked up where I left off last week with the landing light bracket, which involved using the rotary file in the dremel to finish enlarging the center hole. This is what I ended up with (after a few attempts to get the diameter correct on the back bracket hole)
Landing Light Sandwich

Landing Light Sandwich

The idea is that there is just enough thickness in the LED unit to allow for a tight hold when I attach the front bracket with screws. I’ll need to figure out a way to attach this contraption to the nose bowl, preferably in a way that still allows for some aiming adjustment later on.
At this point I have enough of the cowling done to be able to trim the baffles to their final height. I had previously rough-cut them so that they weren’t touching the cowl metal, so all that I needed to do was make a mark where I wanted to cut. To make that line, I poked a small hole about 1.5 inches from the end of a hotel room key. Any sort of plastic would do the job just as well, it’s just that I have a pile of hotel keys available. I stuck the point of a marker in the hole, then ran the edge of the card along the inside of the cowl metal. Some of the lines ended up on the front of the baffles, and some on the back.
Marking the Baffles

Marking the Baffles

Marking the Baffles continued

Marking the Baffles continued

I trimmed the left side so that I could know where I would be able to put the oil cooler. Tabitha came out later in the afternoon to make more window plans. She laid out the new shape in the upper left window and we worked together to cut it out.
Window Thoughts

Tabitha is thinking, looking at the old window shape. In this shape, the plexiglas is layered between the skin and a backing strip. We’re going to change the configuration to put the plexiglas between the steel frame and the aluminum skin, which saves a bunch of fasteners and allows us to enlarge the window a bit.

Bearhawk Front Window Skin

Trimming around the lock mount on the front window

While she worked on that I marked where the oil cooler will go.
Back left baffle Lycoming 360 oil cooler

First, here are the mounting holes.


Then I made marks for where the opening will be.

Note! This oil cooler mounting strategy proved to be inadequate in flight testing. The oil cooler is probably a little bit too small for this engine, but more importantly, it should probably be located back away from that cylinder a little. In the end I fabricated a mounting system that moves the cooler back about one inch. Also note that the ideal arrangement would be with the oil flow vertical. The vertical arrangement would give an outlet for trapped air to flow out of the cooler.
Then I cut out the hole for the opening.

Then I cut out the hole for the opening.

Cowl Hinge

Tabitha picked up where she left off on the cowl door hinge, exchanging clecos for rivets.

We’re both motivated to keep the project moving along.

Posted on
Hours Logged This Session: 7.3
Total Hours: 1883.75

Back Seat Seatbelt Tabs

With the lower cowl in place I started preparing the outer fiberglass scoop that will cover the FAB and direct the intake air to the inlet. I found an RV builder who had a scrap scoop, which was quite affordable. I only needed a very small piece of the original, so any defects or mistakes higher up were not going to be an issue. I marked the edge and used the cutoff wheel in the angle grinder to get the edge pretty close.

Vans fiberglass intake scoop

This is how much fiberglass I cut off of the scoop.

Vans Scoop

Here is the final product, ready for the new fiberglass flange.

I wrote in a previous entry that the radius of the EMT elbows for the exhaust pipes was hard to adjust. Since the number 1 cylinder is closest to the cowling, I started working with it first. I needed a tighter radius, so here is what I tried:
Electrical Conduit Exhaust System

These saw kerfs allowed me to bend the pipe to a tigher radus. It was no trouble to weld the kerfs closed.

This is my second attempt on the number 1 pipe. On the last iteration I had the pipe coming out of the flange at an angle, which made it nearly impossible to get the nuts on. Next I made the seatbelt tabs for the back seat shoulder harnesses. I started with .125 4130 tabs that were 1″ wide.
Rear Seat Seatbelt Tabs

Rear Seat Seatbelt Tabs

Rear Seat Seatbelt Tabs

I shaped them on the grinder and welded them onto the cross tube over the cargo area.

A little bit of cleanup and paint will make that look much better.

Posted on
Hours Logged This Session: 5.25
Total Hours: 1883.75

Initial Prop Install

Today I connected the blue LED that will become the parking brake annunciator. Since the parking brake valve is just a check valve, it could be especially troublesome to land with it in the closed position. The brakes would apply normally, but they wouldn’t release! I’m planning to make this blue light come on any time the valve arm is not in the open position. I used a 430 ohm resistor and stuck the whole assembly into one of the little aluminum casings.

Bearhawk Panel Annunciators

Annunciators- Dynon Warning, Low Voltage, and Parking Brake

It’s time to start making the cowling so that I can build the intake and exhaust systems. The first step is to put on the prop:
Hartzell Propeller

The prop fits! It sure is a hassle to install though.

This allows me to check the nose bowl positioning again.
Bearhawk Nose Bowl Position

Positioning the fiberglass nose bowl based on the spinner location

Since most of the wiring is done I put the boot cowl pieces back in place for a little while. I definitely would not have wanted to do all of that wiring work with the boot cowl on! Back when I cut the side vents in the boot cowl I did it wrong and ended up with a bad shape. Here’s my solution:

Fixing my eroneous vent hole (not a metaphor)

I’ll add one more little D-shaped filler piece and fill the crack with smurf extract. When I put the right side boot cowl on I found a bit of a clearance shortage. The side vent duct is a squeeze between the boot cowl and the electrical distribution panel. Fortunately I think it will still work just fine.
Right Side Vent

Minor clearance shortage

While I had all of that back on I also set the new windshield in place just to see how it fits. I don’t think I’m going to have to trim it at all, which is very nice.
LP Aero Plastics

Windshield Trial Fit

Posted on
Hours Logged This Session: 6
Total Hours: 1883.75

Antenna Mounting

6/21 1015 ground shields, drill left com antenna, add tab to tail post 1235 2.4 hours
This morning I connected the rest of the audio shields to each other. I didn’t have any of the one-ended crimp-on terminals so I just used one half of a yellow crimp-on splice. I found a good spot for the VHF Communication antenna out past the fuel tank, and drilled a mounting hole for it and the grounding screw. I’ll put one just like it on the other side, which will allow for easy connection for the handheld VHF radio.

Left VHF Com Antenna

Left VHF Com Antenna in Wing

I wanted to come up with some method for stabilizing the VHF Navigation feedline in the vertical stabilizer. I added this tab so that I can have something to clamp the feed to.
Tail Post Tab for VHF Nav Antenna wire

Tail Post Tab for VHF Nav Antenna wire

Posted on
Hours Logged This Session: 2.4
Total Hours: 1883.75

Window Re-design

This evening Tabitha came out and we worked more on the left rear window design. We are making a cardboard template that will be the same size as the final lexan piece. This will give me something around which to fabricate a steel structure. The new window will be much larger than the original, on the bottom section in particular.

Posted on
Hours Logged This Session: 4.5
Total Hours: 1883.75

Powering Up the GPS

Today I brought out the Garmin 430 unit so that I could test my wiring. This is a bit of a stressful moment, since the unit is very expensive and I ran all of the wires by hand. I powered the circuit with fuses and used my meter to re-verify every single pin to be sure that power was only applied on the power input pins and that grounds were only continuous where they were supposed to be. With nothing else to test, I put in the box and turned on the switch.

Garmin 430 initial power-up

The moment of truth- powering up the expensive box on my own wiring!

Thankfully, it worked and didn’t start smoking. I ran a few initial coax cables for the antenna feeds, and designed a method for mounting the cat whisker VHF navigation antenna in the vertical stabilizer. I’d like to be able to remove the antenna once the covering is in place, so I will need to have a large enough hole in the covering to allow access to the mounting bolts. This H-shaped arrangement will give me a good hard edge to end the covering on, and a place on which to mount an aluminum hole cover.
VHF Navigation Antenna Mount, before prep and paint.

VHF Navigation Antenna Mount, before prep and paint.

The antenna that I found had a little bit of wear in the solder joints on the balun, so I fabricated a new one out of RG-58. I measured the original and made the new one to match.
New VHF Antenna Balun

New VHF Antenna Balun

Posted on
Hours Logged This Session: 6.5
Total Hours: 1883.75

Intercom Testing

It has been a couple of weeks since I’ve been able to get back to work. I installed the rear audio jacks and created the d-sub connection that I wrote about last month. Since the three non-pilot jacks all share a common audio source, I had to find a way to connect several small wires in a mechanically robust way. Here is the solution:

Combined wires for the Flightcom 403

Soldered D-sub for intercom wire consolodation

The wires go from the cabin jacks to a crimped d-sub connector. That connector plugs into this soldered piece, which is sort of like a mini bus bar for each channel. The three connections are for the audio left and right and ground.
I mounted the intercom box:
Mounted Intercom

Mounted Intercom

Intercom in Panel

Intercom mounted in panel

Then connected the audio wires between the Garmin 430 and the intercom. I wired the push-to-talk switches in the sticks, which allowed me to run the final wire for the intercom. I powered it up and everything works well. Never before has it been so much fun to talk to myself! I wish I could say the same for the audio amplifier circuit that I built. It keeps blowing it’s fuse, so I probably put something in the wrong place. I’ll email Bob N. and see if he has any troubleshooting suggestions.

Posted on
Hours Logged This Session: 4
Total Hours: 1883.75

HS34 Installation

Today was a long productive day in the hangar. I started by installing the HS34 to make sure that the bracket was in a good spot.

HS-34 in Place

HS-34 in Place

Here’s how the instrument panel looks as of today:
Instrument Panel Overview

Instrument Panel Overview

I finished the audio wiring for the front two jacks, and went home to escape the mid-day heat. Our windshield arrived today in a giant box. I ordered it through Mark at Avipro just a few days ago. The date of manufacture is 4 days ago, which makes it about as fresh as it could be. I opted for 1/8″ thickness and pre-trimmed. The smaller thickness will weigh less, and it should still be plenty adequate for our airplane.
Big Windshield Box

The windscreen comes in a big box!

Later in the evening Tabitha and I both came back out to enjoy the cooler temperature. She started by precoating the left aileron for taping.
Tabitha Prepares the left aileron for taping

Tabitha Prepares the left aileron for taping

We worked together on applying the tapes until she was ready to go home. I stayed for a few more hours and did more wiring.
Audio Out jack resistors

Audio Out jack resistors

Left Front Audio Jacks

Left Front Audio Jacks

Messy Intercom Wiring

The intercom wiring is messier than I would prefer for it to be.

Posted on
Hours Logged This Session: 8
Total Hours: 1883.75

Wiring and Covering

Tabitha came out today to help with the covering. She drew the pencil lines for the right aileron tapes while I worked on more wiring stuff. I installed the bracket for the HS34, which was far more difficult than it should have been. For some reason Dynon pre-drilled the mounting holes. This means that I have to try and drill holes in the panel that will match their pre-drilled holes. Since the mount is bent to provide the tension that will hold the instrument tight against the panel, it is impossible to match-drill the holes from the rear. They certainly didn’t do me any favors by pre-drilling the holes! I asked the Dynon reps if they could offer the bracket without the holes, and they said no. I started wiring the front seat headset jacks. The left jack will also host the audio out jack (for recording audio later) so it was a little bit complicated. To simplify things some I decided to move the audio out jack over to the area where the headset jack is.

Posted on
Hours Logged This Session: 5.6
Total Hours: 1883.75

Audio Jacks

I spent a few hours heat smoothing this morning. I’ve been using the 21st Century model airplane covering iron that I’ve had for many years, but today the handle broke. I find myself applying fairly heavy pressure during the process, and it’s probably not designed for that kind of use. I mixed up a batch of JB Weld and reattached it, but it will be out of service until at least tomorrow. I relocated the headset jacks to eliminate the aileron cable interference problem. I moved the front seat jacks to the instrument panel, since this will make for much simpler wiring and shorter routing. I moved the rear seat passenger jacks to the area under the rear door post for the front door.

Flightcom placards

Flightcom provides these jacks, but they will take up too much room on the panel. I’ll use them for the aft stations.

Bearhawk audio jacks

Back Seat Intercom Jacks

Posted on
Hours Logged This Session: 2.4
Total Hours: 1883.75

Audio Wiring Continued

One of the problems that I’ve encountered with the audio system wiring is the high number of connections. Since it is a stereo system, there are even more wires than usual. The Flightcom 403 wiring instructions show several wires that are connected before they make it to the plug that goes into the back of the intercom. I used an idea from Bob Nuckolls to consolidate the wires. I used a solder-cup d-sub connector, which I’ll have a picture of later. After a couple of years of watching and waiting I got a great deal on an HS-34 on ebay. I started laying out the mount for it today, after trimming the left flange off of the D100 mounting tray. Since the instruments have a flange that sticks out a bit past their mount, I also had to widen the hole in the instrument panel a little.

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Hours Logged This Session: 1.3
Total Hours: 1883.75

Audio Wiring

Today I took a break from covering and finished the wiring for the audio isolation amp. I took the cover off of the intercom to adjust the dip switches, which control how the intercom handles music. I prefer for it to mute the audio for incoming vhf transmissions, but not for passenger discussion. Without disabling this feature, everyone would get an “automatic solo” with any singing along. Maybe that wouldn’t be so bad, if it would discourage singing along. I installed the headset jacks in the overhead panel and realized that they would interfere with the aileron cable that runs across the top of the cabin. This is unfortunate, but I’m glad I found the problem now instead of later.

Posted on
Hours Logged This Session: 3.3
Total Hours: 1883.75

Covering Ailerons

The weather is starting to get warmer, so I’m starting earlier and finishing later. Today I recoated the tapes on the right flap. Now it is ready for smoothing

Right Flap Taping Complete

Right Flap Taping Complete

I added the rest of the fabric to the left aileron:
Bearhawk Left Aileron Fabric

Left Aileron Fabric

And used the iron to shrink the fabric:
Shrink polyfiber fabric

Left Aileron shrunk, ready to brush.

Then applied the first coat of poly-brush by brush:
Left Aileron Brushed

Left Aileron Brushed

And added reinforcing tapes to pepare for stitching:
Rib Reinforcing Tapes

Rib Reinforcing Tapes

I also finished riveting the right aileron’s trailing edge and balance tube in place. It is now ready to cover. I started wiring the audio isolation amplifier, which consolidates the various audio inputs into a single channel for the intercom. I finished the power and ground wires today. I’ve saved the audio system wiring for last, since it is by far the most confusing.

Posted on
Hours Logged This Session: 6.8
Total Hours: 1883.75

Electrical Distribution Panel

I deburred the lightening holes in the electrical panel, and removed all of the sharpie ink from layout planning.

Electrical Distribution Panel

Deburred and Clean

Electrical Distribution Panel

Electrical Distribution Panel

Next it was time to get to work populating that panel. I started with the diode bridge for the SD8 circuit.
SD-8 Diode Bridge

SD-8 Diode Bridge

First up is the resistor:
SD-8 Wiring

I soldered the solid lead components instead of using the crimper.

Soldered ring terminal

Like this. Then I covered as much of it as I could with heat shrink.

Here’s the resistor for the capacitor:
SD-8 Capacitor

A little heat shrink will help limit shorts.

SD-8 Capacitor

SD-8 Capacitor

Here are most of the other components:
Electrical Panel

There are two problems here. First, I had to remove the jack on the middle of the right side. That was for alternator diagnostics, but with the Plane Power alternator that isn't available. Second, the ebus diode, just above the junction of the two fuse blocks, wasn't well enough insulated, so I changed the mounting later.

From left to right, top to bottom: Main bus fuse block, ebus diode, ebus fuse block, alternator diagnostic plug (later removed), SD-8 Diode Bridge, ebus relay, SD-8 Relay, SD-8 Capacitor, SD-8 Regulator, and SD-8 Crowbar overvoltage module.
And the back:
Back of Electrical Panel

The components also add a lot of stiffness.

I’m attaching that panel to the fuselage tubes with adel clamps, so I thought I’d make a copy of a tool to help install those clamps. The V on the end goes into the threads of the bolt that secures the clamps, relieving tension on the nut after compression. That makes a 3 hand job into a 2 hand job.
Adel Clamp Tool

Adel Clamp Tool made from thin stainless.

Here’s the panel in place. I didn’t realize at the time, but it’s going to crowd the duct for the right front seat passenger vent.
Panel in Place

Electrical distribution panel in place

Since the weather was nice I also cleaned and primed the steel straps that connect the rudder cables to the rudder pedals.
Rudder Cable Straps

Here the other side is ready to paint.

More Electrical Infrastructure

Today I picked up where I left off yesterday, adding a few more parts to the power distribution panel.

Populating the Panel

A few more items on the panel

Electrical Distribution Panel

It's getting a bit more crowded.

Next I started making a few parts to mount the audio amp and the low voltage warning.
Homemade Circuits

I decided to combine the two homemade circuits in an enclosure made from scrap aluminum.

Circuit Enclosure

This enclosure will provide mounting and short protection.

The next challenge was to cut a hole with the odd shape of the d-sub.
d-sub shaped hole

Here's how I cut an odd-shaped hole- drill the corners, then the dremel wheel to connect the dots.

The crowbar overvoltage module for the SD-8 doesn’t have any easy mounting options, so this is the best that I could come up with:
Crowbar Overvoltage

The clothespin holds the module while the JB Weld sets up, then I'll screw the small piece of aluminum to the distribution panel.

I also cut two more odd-shaped holes for the Dynon serial cables. These will be for firmware updates and that sort of thing.
Dynon Serial Holes

Two out of three- one for the D180, one for the D100, one to come for the HS34.

I allowed myself to become a bit distracted from electrical work to address a couple of other issues. First, the steel tabs that I made for the rudder cables were starting to rust. I took them off and dropped them into a bucket of phosphoric acid that I was also using to start prepping exhaust conduit parts.
Rusty Parts

Bare steel rusts quickly in the hangar.

I also installed the Dynon OAT probe. This is the probe version that connects to the D180, not the version that connects to the magnetometer. I wanted to put it somewhere with the minimum drag penalty and minimum damage risk, so I chose the spot right behind the wing strut junction. I figure that the air through there is going to be so turbulent that the drag penalty will be minimal, and it will be out of the way of birds and bugs.
Dynon OAT

Dynon OAT probe location

Next I drilled the control sticks for the push-to-talk switches.
Bearhawk Control Stick Wiring

This is just a pilot hole. The final hole has to be big enough to clear the switch.

Push-to-talk hole

This hole is right in the middle of the top of the stick. I'll cut a corresponding hole in the grip for the switch to protrude.

Today was a good day with lots of time in the shop. Several months ago I found that 4 hours was about all that I could work. Now it seems that I’m only limited by the need for food and restroom breaks, and weather extremes. I’d rather just be out there working all day.

Electrical Parts & Weight

Today I started with an inventory of parts for the electrical system.

New Electrical Parts!

Getting new parts is so much fun!

I’m using several d-sub connectors for the avionics, so I set them all out and wrote notes about which one needs to go where.
D-Sub Organization

I labeled some of the d-sub connectors that I know I'll need.

More New Parts

Switches, LEDs, Terminals, E-Bus Diode, etc.

Molex Crimpers

These molex crimpers are nice, though the wire sizes are listed on the box but not the tool.

Fuse Blocks

One of these will be for the main bus, one for the ebus. The top of the picture shows my test lead for the low-voltage module.

Small Fuses

I ordered the small fuses from B&C since I couldn't get them locally.

Now it’s time to put some of those new parts to work! First, I installed the switches.
Right Row of Switches

The switches in this row are for lights.

The switches are divided by function, with lights on the right, and the others on the left. Both banks are within comfortable reach from the left or right seat.
Left Switch Section

These switches are for the magnetos, starter, and power distribution.

I spent a little bit of time getting the tip of my soldering iron reshaped and tinned, and fixed the AEC 9005 Low Voltage Warning Module. This is the one that I built per the Bob Nuckolls design. It wasn’t working after I first made it, but that was because I put a few parts in the wrong place. After I had all of that sorted out, it works great with my test harness hooked to the truck battery. This module is very simple and useful- it flashes a red LED whenever the master switch is on but the alternator isn’t. It’s important for the pilot to be aware of such a condition, because in flight it means that the alternator has quit and the system is consuming finite battery power. On the ground after shutdown it is a flashing reminder to turn the master switch off.

I wasn’t happy with the crimp results I was getting on larger electrical cables, so I’ve tried another method. The underlying problem is that the terminals are much larger than the conductor of the cable.

Improved large wires

The calipers are set to the OD of the 4 AWG copper wire. The terminal is an unmodified 4 AWG size, and this picture illustrates the difference.

Bob Nuckolls suggested that I stick copper wedges into the strands to tighten the fit, then crimp or solder. An alternate technique that I tried was removing material from the terminal to reduce its inner diameter. This provided a snug fit, then I soldered the able to make the joint gas tight.
Modifying oversized terminals

I put the terminal in the vice with very light pressure then used the Dremel to remove material.

Ready to Solder

I put a little flux on the copper conductor then squished the terminal in the vice.

This method produced a much better product.
Ground Cables

With a little heat shrink these ground cables are looking about done.

Engine Grounding Cable

This cable is surprisingly important, though it seems fairly minor.

Danny was borrowing a set of scales, so we figured since they were at the airport we should go ahead and weigh the Bearhawk as it is.
Bearhawk Weight

As of today, the weight is 885 pounds.

If I had a set of scales like this around all the time, I think it would be an interesting experiment to weigh the airplane weekly to see how it becomes so heavy. We’ll likely add another 400-500 pounds before we’re done. I also took a couple of overview shots since I didn’t have any good pictures with the wings on.
Bearhawk Front Overview

From the front right...

Bearhawk Left Side

... and the left.

These pictures will mean a lot when the airplane is finished.

Position Lights and Brakes

It was too humid this morning to spray the next coat of polybrush, so I worked on the wingtip instead. I mixed up a batch of epoxy and used it to attach the position light mount and the wingtip aluminum strip.

Attaching the Position Lights

I didn't have any paper masking tape, so I used a little bit of foil tape to hold the position light mount in place.

Wingtip Filler Strip

Wingtip Strip

I also made a short brake line for the left side and hung up some blankets to serve as drapes. Half of the front of the hangar is translucent, and I was concerned about unnecessary UV exposure.
Spray Booth

Here's my "spray booth" with most of the improvised curtains.

Brass Grounding Tabs

Today I started making the brass grounding blocks. My orders from Stein and All Electrics came in- great fun!

New Goodies!

New Goodies! D-sub crimper, brass tabs, assorted electrical bits.

More New Goodies!

More new goodies, including some BNC crimp-on connectors, and the parts to make the Bob Nuckolls alternator diagnosis jack.

The brass terminal strips were available from Stein for $1 each, so a few minutes of soldering and a $3 piece of brass from the hobby shop saved me $50 or so from B&C.
Brass Tabs

The tabs from Stein come in strips of 10 tabs each.

Brass Stock

Here's the layout on the brass stock


I used two large brass bolts instead of one brass bolt and two little bolts as on the B&C version.

Soldered Bolts

I soldered the heads of the bolts to the interior sheet so that I wouldn't need to hold them in place for tightening.

Soldered Tabs

Since the meco torch was handy, I installed a 0 tip and used it to provide the heat for soldering. Even with the tiny tip I still kept the flame several inches from the work and hand plenty of heat.

The flux looks pretty bad in the picture above, but after some time with a toothbrush and some rubbing alcohol it cleaned up well.
I also took apart the VHF Nav antenna that I picked up in the Aeromart at Oshkosh. It was very inexpensive, and I was planning to use just the conductors. I’m still trying to figure out how to make a mount that will work well on the fin.
VHF Nav Antenna

VHF Nav Antenna Parts

I installed the brake reservior on the engine side of the firewall with one of the holes in a support tab for the firewall.
Brake Reservoir

Brake Reservoir on the Firewall

My goal is to not have any bolts holding on just the firewall, since there are so many little parts that need to be mounted to the firewall too. I did need to shorten the tabs slightly because of the somewhat short reach of the -3 clip nuts that I had. I put the paper towel between the firewall and the tab so that I could use the dremel to cut the tab without scratching the firewall.
Shortening the Tab

On the left side you can see the paper towel pad.

I debated briefly about whether or not I wanted to have the reservior on the engine side of the firewall. The benefits would be ease of servicing and reduced possibility of interior leaks. The only drawback that I can think of is that the possibility of problems in the event of an engine fire. I decided that in the event of an engine fire I’m not going to be too concerned about the status of the brake reservior! The brakes will still work once or twice without the reservoir in the system anyway. I drilled a hole in the firewall for the line to pass through, then realized that the location of the hole was going to be too close to the brake pedals. I’m concerned that there is a remote chance that the fitting might interfere with the brake pedals, so I’m going to move it up a little.

Posted on
Hours Logged This Session: 3
Total Hours: 1883.75

Aligning Tail Pieces

On a recent trip to Harbor freight I picked up another pair of adjustable height support stands to help figure out why the tail doesn’t seem to be lining up right.

I used these stands in an effort to more reliably position the tail pieces for measurement.

I leveled the fuselage left-right with a water level at the wing attach points. From there I levelled each stab half with a bubble level.
Left-Right Level

I used a bubble level to level the stab halves, carefully positioning it between rib stitches.

I also raised the tail to level the stab halves front-back and then rechecked the other measurements. I spent lots of time scratching my head, but here’s a summary on what I have so far. The stab halves seem to be built with a little bit of error in the vertical positioning of the parts. I wonder if the left and right halves were built in the same jig, such that a slight error due to gravity would be down on one half and up on the other half, thus providing the 1/8″ or so error that I see between the left and right halves. My solution is to adjust the hinge supports a little so that the elevator halves will be parallel, and just accept the error in the trim system.

Straght Trailing Edge

From this angle you can see that the trailing edges of the two stab halves are parallel.

The trim horns don’t quite line up right, so there will be a little bit of binding and friction. Since the trim system needs a little friction anyway, this will work out well. Also, the trim horn only moves slightly, so I don’t know if the binding will even be noticeable in the range of motion that it will see in service.
Trim Horn Alignment

Note the trim hole alignment as I rotate the horn.

Trim Horn Alignment

Notice that with the horns turned 90 degrees, the misalignment is still only vertical.

Trim Horn Alignment

Finally, here is a shot with 180 degrees of rotation. These pictures convince me that the trim shafts are straight but not coaxial.

In the end there might be a slight difference in height between the left and right stab halves (1/8″ or so) but both will be level with reference to the wing attach points, so I’m not really concerned.
Right Tube Verification

I verified that the removable pieces were installed correctly on the right...

Left Side Verification

... and on the left.

I spent some time getting the aluminum part of the flap handle finished. I drilled holes where the notches would go, and plan to take the piece home to cut out on my wood cutting bandsaw. I started making up the fuel lines that connect the tanks to the inboard rib. Tonight at the EAA meeting Wade brought his punch and cut out the lightening holes in the battery box.
Wade Punches

The picture is a little bit blurry, but here Wade is punching the holes at the EAA meeting.

The conduit punch had no trouble with the thin steel.

Posted on
Hours Logged This Session: 2.1
Total Hours: 1883.75

Installing Fuel Lines

Today was a full day of making fuel lines. I’ve remade a couple, and need to remake a couple more. There are a few noteworthy points that I’ll pass along about the process. First, bending the 5052 is a one-time operation. Since it work hardens after bending, if you bend it to 90 degrees when you really only wanted 87, you can’t unbend it by 3 degrees. The best that you’ll be able to do is put a 3 degree bend in the opposite direction right next to your 90 degree bend, and that looks pretty tacky. Second, using a welding rod or coat hangar as a template is worth it, even if you have to toss out the wire after a few lines worth because it is all bent up. This is in addition of course to the all important advice of making sure that you put a nut and sleeve onto the tube before you flare the end, but I’m sure you’ve heard that one before.

Here are a few pictures of my progress:

The fuel line on the left side under the door.

The fuel lines under the floor, looking up from ground level.

Here's the junction just in front of the right door

I had trouble coming up with a good way to route the line on the right side so that it would be out of the way of the cargo door. I cut this notch in the door sill in hopes that I’ll be able to route the line through there, but it is a tight corner going forward.

The first notch for the aft right line

While I was at Oshkosh I also picked up a piece of 1/4″ aluminum to make the door jamb fuel line shims out of. I started filing them down, but it is a long process.

Posted on
Hours Logged This Session: 7
Total Hours: 1883.75

Reinventing the Window

Another suitable title for this post would be “Defenestrating the Stock Window Design.”

Tabitha and I have been discussing windows ever since our cookout and during our visit to Oshkosh. She says that the existing stock windows aft of the front doors are too small and too few, while I contend that they are completed and require no more work. In return she says that’s not a good enough excuse for them not to be just as she wants them. While we were discussing the matter in the Avipro booth at Oshkosh, Mark very tactfully told her that making changes prolongs the completion date. I didn’t ask him to say that, though if I had thought of it in advance I would have orchestrated it for sure. She has offered to provide the labor to make the change, so she is going to start figuring out what the ideal configuration will be.

Tabitha made up a plastic sheet and marked it with the locations of the structural members so that she could try out some window arrangements.

The first proposal is in red, which makes it somewhat difficult to see in the small version of the picture. Click on the small one to see the full-size version instead.

While she was doing all of that I tried drilling a hole in the gascolator bolt for safety wire. I asked Bob whether or not the gascolator needed any safety wire, and he said that he was comfortable with it not having any, since the friction from the o-rings would provide a thread locking feature. He did say that there wouldn’t be any problem with drilling a hole to make a provision for safety wire, so that’s what I did. It’s easy, only took a few minutes, and is done. I was able to find some coarse bolts that were a little bit too long, so I shortened them and cleaned up the threads.

Here's the hole before deburring

With an adequate full-size drawing of the proposed windows done, we agreed that the existing baggage door skin will need to be replaced.

I also spent some time building the little access panel on the boot cowl again. I don’t remember if this was the last one or not, but I’ve made several.

Reinventing the same piece over and over again- Here I am in another iteration of the panel that I have made a few times. I've lost track of which version this was.

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Hours Logged This Session: 3.9
Total Hours: 1883.75

Starting Fuel Lines

Since I’ll be on the way to Oshkosh shortly, I wanted to spend some time figuring out the fuel and brake systems again. This will allow me to buy the few remaining parts that I don’t have. I have had some 3/8″ .035 5052-0 line for a while, but I figured I should try bending and flaring some before I go to OSH in case I need to pick up more spares of that too. My first realization is that the 5052 work hardens really well- so well that I really only get to bend it once. If I bend it to 90 degrees when in fact I only needed 88 degrees, It’s pretty much impossible to bend it back to 88 again. This meant that I had quite a learning curve and made a few pieces of silver macaroni. I remembered the trick that Tony B suggested and tried making some templates out of welding rod first, and that helped.

One of the requirements of the fuel system is that everything flows downhill to the gascolator. Since the door jamb that the T fitting bolts to is sloped aft, this would create a low spot where water could be trapped.

Fuel Fitting Angle

This would be the fitting of the angle without any shims.

I wanted to try to eliminate this problem by making shims to angle the fitting closer to level.
A better angle

Here's a better angle for the fitting.

Another idea

This idea didn't work.

Aluminum shim attempt

Here's the making of an aluminum shim. This one turned out to be too thin at just 1/8 inch.

Shim concept

Even though these are too thin, you can see how they would work.

With that operation tabled pending some thicker aluminum, I started working on getting the fuel valve in the right place. This isn’t supposed to be hard, but it isn’t going well. As pretty and nice as the Andair valve is, the problem is that the outlet is on the bottom. Even with an angle fitting on the bottom, it is a little bit too tall. In order to keep a downhill slope from the valve to the gascolator, the valve has to be a few inches forward of the gascolator.
Locating the fuel valve

Locating the fuel valve

Another note from the future- I’ve decided not to use this fuel valve. There is another option that is much better suited to this type of installation. The other valve doesn’t have an outlet on the bottom, and the inlets are situated lower, so it will not protrude below the stringers.

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Hours Logged This Session: 5.7
Total Hours: 1883.75

Welding and Priming

The only parts that didn’t survive the move when we purchased the project were the tail struts. I haven’t been able to find them anywhere, and neither has Richard. This is unfortunate, since they are fairly expensive. I was able to buy another set from Mark, though he cautioned that they may need a length adjustment. After getting everything level for the tail pieces, I realized that one of the the struts was just a little bit too short. As you can see below, I removed the original end and welded in a new end that Mark also provided.

Adjusting the length of the tail struts

Adjusting the length of the tail struts

New end in place

I also added a small patch tab to the part of the tube where the old fitting was.

I never was able to understand why the two engine control tabs are mounted where they are. I am going to have three engine controls, and I’d like to have the prop control centered in the panel. Since these two tabs are situated around that location, it would be hard to use them. The solution was to cut them off, make a third tab, and put them where they needed to be.
Cut them off

Step one- cut the existing tabs off

Step Three- Put them where they should have been

Step Three- Put them where they should have been

Step 4- finish weld

Step 4- finish weld. Don't they look like little tombstones?

Shiny Tombstones

Shiny tombstones, ready to prime

I also cleaned up and primed several other welding areas. The bare steel rusts so quickly that it makes sense to prime these areas as soon as possible after cleaning them.
Control Stick Ends

Here are the cleaned and primed control stick ends

Panel adjustment area

Panel adjustment area cleaned and primed

After some more considerable measuring and head scratching, I noticed that when the elevator halves are joined at the middle, they don’t line up with each other.
Right Elevator

Right Elevator aligned with Stab

Left misaligned

...means that the left half doesn't line up with the left stab.

Elevator Trailing edges

Here is the same view of the trailing edges. Note that the left is lower than the right by a measurable difference.

I’m still not really sure about exactly what is going on here. The suggestions from Mark and others are to make sure that all of the pieces are installed correctly, but it certainly seems as though they are.

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Hours Logged This Session: 4.4
Total Hours: 1883.75

Rudder Pedal Springs

Sometimes building an airplane involves taking three steps forward, sometimes it means taking a couple of steps back. Today I spent a little while adapting some springs for the rudder pedals, but I don’t really like them. I also spent a while making the third version of the boot cowl panel, and also made it wrong again. This is the couple of steps back day.

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Hours Logged This Session: 2
Total Hours: 1883.75

Test Fit Engine

Today was a busy day at the hangar. I started by drilling the holes in my new rudder pedal-cable straps. I wanted to be sure that the four straps were match-drilled, so I used a scrap piece of aluminum angle and some c-clamps to hold the straps stacked in place. After the first hole I added a cleco to keep the straps from sliding around. The aluminum angle didn’t survive very well, but it did the job.

Holding the Straps for Drilling

System for holding the straps down for drilling

End result- matched holes

The result was a set of nicely matched holes.

Now I just needed to know what kind of rudder pedal springs to shop for. I measured the distance with the rudder hooked up.
Measuring for the Rudder Springs

Measuring for the Rudder Springs

Since welding the skylight tabs was on the horizon, I used some scrap pieces of steel to weld up a jig. This is inspired by one that Eric shared, though it is slightly different. The key is that the middle leg is shorter than the other two, and that each tine is slightly bendable. The idea is that the outer two tabs will rest on the parent tube, while the tab will rest on the middle tine.
Tab Welding Fixture

Here's the crude tab welding fixture

With Oshkosh coming, I wanted to measure the length of the engine controls that I’ll need so that I can be on the lookout for some bargains. I tried taking measurements with the engine off, but it wasn’t working too well. I got some hardware store bolts to use as temporary fasteners while I wait to order the AN bolts at Oshkosh. This was all that I needed to get the engine temporarily in place, both to measure the cable runs and to inspire more progress. It was really a fairly simple job. I positioned the fuselage close to the engine on the pallet, propped the tail up so that the fuselage was close to level, and added some weight to the tail (just to be sure that it wasn’t going to nose over).
Positioning the Engine

Positioning the Engine

I used the lift to position the engine, then started sticking the bolts in. It was a strange feeling to lower the lift and let the fuselage and mount carry the weight of the engine for the first time. Of course it is strong enough to carry this weight at 6 g’s or more, but it just seems so strange at first.
Engine Installed

Engine Installed- for the first time.

My measurements were a little bit easier with the engine in place. I figure that 48″ will work for all three of the controls, depending of course on how I route them.

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Hours Logged This Session: 3.8
Total Hours: 1883.75

Rudder Pedal Geometry

In our last episode, I was moving the rudder pedals forward to address the potential over-center problem that Mark at Avipro brought to our attention. Back when Richard was building, the consensus was to locate the rudder pedals for ergonomics. Subsequent experience led to a new recommendation to locate the rudder pedals exactly as depicted on the plans. To meet those requirements, I ended up moving the pedals forward just about as far as they could go.

New Rudder Pedal Location

Here's the new location, and you can also see the old hole.

After moving the rudder pedals, I noticed right away that the brake cylinders would be touching the forward-most tubes when the pedals were at max deflection. I wanted to measure the rudder deflection so that I could see if the pedals would stop before reaching that point. To measure the rudder deflection off of a theoretical fuselage centerline, I needed to measure the angle formed by the fuselage sides so that I could subtract it from the desired total deflection.

Figuring out the angles

Measuring the angle of the fuselage sides so that I can create a template for measuring rudder deflection

Final Answer

Here's the final answer- 40 degrees on the template; 10 for the fuselage side and 30 for the deflection.

After all of that hassle, the final answer was that the rudder was at exactly the right deflection when the horn hit the stop (with no bolts in the tubes). Also, the brake cylinders do not contact the tubes at max deflection, but they are close!
Rudder Stops

Perfect deflection with no added bolts. For some reason I thought that I was supposed to have bolts in there- I guess not!

While I was thinking about it, I wanted to measure the rudder horn to see if it was the original design, or the temporarily different design. At one point there was a change in the rudder horn, then a few years later it changed back to the original design again. I believe that we have the interim horn size. Eric says that this change was simply one of control sensitivity, and that his is also the shorter interim length. The shorter length here means less pedal movement for the same amount of rudder deflection. I’m not planning to change the horn back to the original length, since I didn’t think that the rudder was too sensitive on Eric’s airplane, and since the change is optional.
Measuring the Rudder Horn

Measuring the Rudder Horn

With all of that head scratching done, I took a break to get a few things done at home. I came back later in the afternoon to start work on the steel tabs for the skylight structure. I wanted the option of using nutplates in the tabs, so I sized them with that goal in mind. (Mysterious note from the future: I subsequently decided not to use nutplates on most of the tabs, just because the skylight screws are going to be very rarely removed, and because access is easy with another person comfortably seated in the cabin)
Planning the tab size

Planning the tab size

Pile o tabs

Here's a pile of all of the rough cut tabs.

Since I moved the rudder pedals forward, I found the cables to be too short. My remedy was to make new steel attach straps. I used the materials and specifications from the Beartracks and Avipro assembly manual. As you can see in the picture below, I used a washer to draw the radius for the end.
Rudder Pedal Straps

Blanks for the new rudder cable straps

4 strap blanks

Here are the 4 straps- two for each side.

The next step is to drill the holes and install the straps.

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Hours Logged This Session: 4.8
Total Hours: 1883.75

Cable Guard Nutplates

Today Tabitha came to help. She installed nutplates in the floorboards for the rudder cable guards while I took care of a few loose ends.

Tabitha makes nutplates

Tabitha is installing nutplates


Here are the first few.

I was recently reading through the Beartracks newsletters and came up with a few things to check on. The first was the flat plate of steel that joins the two flap cables behind the aft bulkhead.

Measuring Flap Junction

I also checked to be sure that the flap junction plate was 1/8\

In the time since Richard installed the rudder pedals, there has been a potential over-center rudder pedal problem that has come up. I needed to move the pedals forward to eliminate this problem.

Measuring for Rudder Pedals

Measuring for Rudder Pedal Placement

While I had the rudder pedals out, I was also able to turn the bottom engine mount bolts back around. It isn’t possible to install them correctly while the rudder pedals are in place. In the picture I’m tightening the top bolt.

Engine Mount Bolts

Here I'm working on the engine mount bolts.

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Hours Logged This Session: 5.8
Total Hours: 1883.75

Elevator Patch and Cable Guards

Today’s efforts include a morning session of fabric work and an evening session of sheet metal work.

Richard had started the taping process on the tail pieces, but some are still in the works. Since one side still had exposed rib laces, I figured that I would check to be sure that they were spaced properly. Of course they were.

Rib Lace Spacing

I measured the rib lace spacing to confirm that it complies with the Polyfiber chart.

Elevator Overview

Here's a view of the elevator

Hard meets Soft

Since the aft edge of the lead weight is a hard spot on the soft fabric, I believe that it needs a reinforcement.

Preshrinking Fabric

Since the reinforcement is made from preshrunk light fabric, I built a wooden stand to use for the preshrinking.

Ready to Shrink

A quick lap with poly tack, 30 minutes of drying, and it's ready for the iron.

Shrunk and ready to cut

The iron really takes those wrinkles out!

The next task was to investigate the sound of something rattling around inside one of the elevator halves. I narrowed it down to the balance area, and made a cut in the fabric to investigate.

The offending piece of lead

Here's the culprit- a little piece of lead from somewhere.

I know it is counter-productive to cut off pieces of fabric before they are even completely applied, but I wouldn’t be able to live with myself if I knew that something was still in there. It’s much easier to repair now, before the aerothane starts flying.

Elevator Surgery

Fabric Removed, Ready to Clean

Lifting the Polyfiber Tape

A little bit of MEK and some rubbing made it easy to lift off the old tape.

Cleaned and Ready to Cover

Now I just need to recover the balance area.

First Comes the Fabric

First Comes the Fabric... (with adequate overlap per the polyfiber manual)

Stay tuned for the rest of the repair. This week featured especially moderate morning temperatures, which is why I’m able to do any fabric work at all in June. Even so, I’m limited to working in the mornings. Now skip ahead to later in the evening, when I came back out to the hangar to work on the rudder cable guards in the cabin.

Trimming the Aft Edge of the Rudder Cable Guard

Here I've trimmed the trailing edge of the rudder cable guard to match the angle that it forms with the aft cabin bulkhead.

What a nice fit!

What a nice fit! I'm going to replace that aft bulkhead with fabric instead of aluminum, but it will still fit nicely then too.

Left Side Guards

Here are most of the left side guards in place.

Right Side Guards

Here are the right side guards. Do you see the problem yet?

Rudder Cable Guard Interferes with Door Opening

As you can see from this angle, the aft cargo door opening coincides with the aft right guard. How am I going to fix this?

First, put the door on.

First, I should put the door on and see exactly what I'm working with.

This is how I'm not going to fix it

Here's a great idea that didn't work. I can't move the door sill up without shortening the door.

Here is where you can insert the picture of some serious head scratching. It’s time to get out some paper or card stock and try some different ideas. After a few more failures, here’s a promising possibility:

This looks better

The new and improved option.

The final result

This is the finished part.

While I was holding this part, I realized that I was unlikely to think up something like this theoretically. The only way that I was going to make something like this was to cut up some templates and mock it up on the actual airplane. I hate to waste shop time scratching my head, but sometimes that is the way it has to be.
Another View

Here's another view, just in case you are going to try to make something similar.

Working in these two separate sessions worked out well today. I find that in some cases my productivity suffers after 4 hours of continuous shop time, and during the hot part of the day I try to stay out of the hangar/oven.

Posted on
Hours Logged This Session: 5.1
Total Hours: 1883.75

Boot Cowl and Tail Examination

Today I cut out a new piece of aluminum to replace the one that I made wrong (and that I would make wrong again) while Tabitha dimpled the stainless exhaust tunnel and installed nutplates on the appropriate sections. I also calibrated the iron in preparation for covering and started to evaluate the tail pieces to see what all they needed.

Tabitha is changing out the dies in the hand squeezer

Here's another attempt to cut out a piece that I made incorrectly.

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Hours Logged This Session: 3.3
Total Hours: 1883.75

Drill, Debur, Dimple, Nutplates

Today was a day with lots of hours and not a lot of pictures. I finished the work on the left air intake, which included dimpling the boot cowl and cutting countersinks into the plastic vent. I also dimpled all of the holes in the boot cowl skins that will get rivets, except for the firewall flange. I wanted to wait to commit to fasteners on the firewall flange until cowl time. I added some missing nutplates to the glareshield hatch (the corners that needed single lug nutplates) and started adding the nutplates to the lower boot cowl panels.

Install Nutplates

Here's a nice row of nutplates (in the wrong place)

Above you can see that I put the nutplates on wrong. I have made this panel 3 times now, so hopefully it is correct (speaking from the future again).

I also cut off some long strips of aluminum to use for the wingtips, and started preparing the stainless tunnel piece for it’s nutplates. It is so thin that dimpling is the only option for the nutplate rivets.

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Hours Logged This Session: 7
Total Hours: 1883.75

Engine Mounts and NACA Scoops

I’ve been watching the price of the engine mount rubbers for the past few months, and the trend seems alarming. In the 2008 Vans Accessory catalog, they were $40 per lug (for a total of $160). Today Vans sells them for $125 per lug, or $500 plus shipping! Yikes! I was surprised to see the cost go up so quickly. I was looking for some way to spend less, and eventually found that Jeppesen of all places sold them. Their price was well below anything else that I could find, at $88 per lug. My only explanation for this was that their price was outdated, but who knows. I was glad to save so much money. Here’s the data from the box:

Lord J-7402-24

Lord J-7402-24 Engine Mounts

Nobody seems to know how long the bolts need to be for attaching the mounts to the engine. I don’t really understand the mystery- the mounts have a center tube that gets compressed to the washers on either side. Now that I have them on hand I can measure the length of that tube and the end washers to come up with a grip length for the bolts. Here are some pictures of my measurements, in case you find yourself wondering how long the bolts should be.

This was just the uncompressed length, not very useful.

Washer Thickness

Here's the thickness of the end washer. It's just a little bit more than .1 inch

Measuring Again

Here's another somewhat useless measurement- the uncompressed gap between the two big pieces.

Here's the uncompressed length of the pair

Rubber Engine Mount Thickness

Here's a much more useful measurement- the thickness of the assembly once it is compressed.

Thickness of Engine Ear

This is the measurement that I took of the thickness of the engine mounting ear on the engine. This one isn't especially accurate, but is pretty close.

For the purpose of ordering bolts, my measurements aren’t especially accurate, since the bolts generally come in 1/16″ increments. I figured that the compressed rubber was 2.03″ and the engine lug was .93″. This makes the required grip length for the -7 bolts 2.96, not counting for any washers (and I’ll need at least one of those at 1/16″). The AN7-34 is 2 15/16″ (2.9375″), so I ordered the 7-35 with it’s 3 1/16″ grip length. That will allow for a washer or two but will keep the bolt’s threads out of the way.

With that bit of research done, I started working on the air intakes that will go on the sides of the boot cowl. These will provide fresh air for the front seats through an eyeball wemac type of vent on the instrument panel. I got the scoops from Vans, their part SV-1 at $6.25 each.

Vans NACA Scoop

Here's one of the scoops from Vans, along with a cardboard template that I made for marking the aluminum skin.

I wanted to make an aluminum backup ring so that the plastic part would be sandwiched between two layers of aluminum. The cardboard template made that step easy.
Aluminum Backup Ring

Here are the two rings and a nice view of the back of the SV-1

I drew a few lines on the boot cowl to try and figure out where I wanted to put the vent. My primary goals were to make the centerline of the intake horizontal in level flight, and to keep the intake lower than the outlet inside, so that water would be more likely to drain out if we were flying in the rain. I’m curious to see if this works. Note from the future! This vent installation is wrong. The hole is cut to the wrong shape- the aft portion of the vent should be straight across, not rounded.
Boot Cowl Layout

Here's the mark on the boot cowl sheet for where the vent will go. I almost oriented the vent backwards! This is the right side of the airplane, with the nose facing right.

Boot Cowl Vent Intake Location

Here's a more wide-angle view of where the vent will go.

vent on flat skin

Here's the boot cowl skin flattened out and ready for cutting the hole.

Ready to dimple

Now I just need to dimple the skin, countersink the plastic, and put everything aside until I'm ready to permanently attach the intake.

See note above- this is wrong. The aft side of the hole should be a straight line. I didn’t realize this until I was looking at Patrick’s RV in November 2010.

I got to the point of dimpling the holes for the first side and had to quit for the day.

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Hours Logged This Session: 4
Total Hours: 1883.75

Headset Jacks and Door Sill

I started out today by finishing something from last week.

Top Stringer Forward Attach

This is the forward attachment for the top stringer, looking up and slightly forward.

While I had the torch out, I also added a few more parts to the skylight area. First up were some plates for the headset jacks.
Headset Jack Plate

This plate will hold the headset jacks for the front and rear set occupant on one side.

This plate goes on the spanwise mini-bulkhead that I’m creating at the aft side of the skylight. This is what it looks like with a couple of the jacks installed temporarily.
Headset Jack Plate Populated

The switch is required to specify stereo or mono headsets. I've never seen an intercom that required such a switch.

Both Plates

The holes started out as small pilot holes, as you can see in this left-right before and after picture.

Headset Jack Plate Installed

Here it is after welding in place

This location will put the headset plugs and cords up and out of the way, behind the front seat passengers and ahead of the back seat passengers. Update from the future: This location doesn’t work. The aileron crossover cable interferes. Put the jacks somewhere else!

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Hours Logged This Session: 4.25
Total Hours: 1883.75

Repositioning Door Area Flange

Today was a two-part day. In the first session, I used a dremel tool to remove the weld on the vertical portion of the door threshold at the forward end. This was to allow for repositioning that piece so that it would attach properly to the aluminum piece that goes there. This also involved cutting loose the piece that I added on earlier.

This is the forward lower corner of the front door. I've removed the weld and the paint in the area so that I can bend the whole vertical piece out some.

This is the same piece that I added earlier in the year. This time I trimmed it and moved it inboard some to allow for the aluminum panel.

I also addressed a small scratch that I made on one of the engine mount tubes. I sanded the area with fine sandpaper to remove the scratch, then sprayed a little bit of temporary primer to keep it from rusting.

Engine Mount Touch Up

In the second session I added on the front tubes for the skylight, cut the chordwise tubes loose, bent them to a slight curve, raised the front piece up, and cut out some new stringer tabs. This is all work that I wrote about a few entries back.

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Hours Logged This Session: 3.5
Total Hours: 1883.75

Seats and Engine Mount

Today Tabitha came out again to finish squeezing some more wingtip rivets. We also tested the glue on the foams to make sure that it wasn’t going to dissolve them. The glue checked out OK, so we glued one of the bottom cushion combinations. Tabitha marked it for cutting and spent some time thinking about how all of that needed to be done.

Tabitha is trying out a few different seat foam combinations and marking them to cut.

While she was doing all of that I worked on more nutplates in the boot cowl/fuselage area. Danny stopped by, and he and I installed the engine mount.

Posted on
Hours Logged This Session: 5.5
Total Hours: 1883.75

Nutplates on Panels

Today was a short day, but I was able to spend some time on the nutplates that will hold on the “optional” aluminum panel under the door. I learned about a few complications.

This is a hole for the nutplate that will hold on the aluminum panel under the door.

First, the nutplates won’t work well on the top unless I bend out the steel piece at the bottom of the door. The surface of the panel and the surface of the nutplate’s support have to be parallel. As it is, the steel piece is bent inward to help keep it from chaffing the fabric.

The second problem is that I have way too many holes in that panel! I’m going to spread them out a little on the top, and the door sill plate will help hide the unused holes (and share the used holes).

Here's a test flush #8 screw.

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Hours Logged This Session: 1.5
Total Hours: 1883.75

Tailwheel Spring and Wingtip

Tabitha came out today too and we made some good progress. I was at a stopping point with the tailwheel spring because I didn’t have a drill that would handle larger bits. It had a temporary bolt in place of the AN-7 that is supposed to go in there. With the new drill I was able to get the hole up to size and reinstall the tailwheel spring.

I got this new drill so that I could use larger bits. All of my others have a 3/8\

Meanwhile, Tabitha was dimpling and squeezing the rivets for the wingtip flush mount strip.

Tabitha was dimpling and squeezing.

I also spent some time getting ready to install the engine mount, now that I have the hardware.

Posted on
Hours Logged This Session: 5.1
Total Hours: 1883.75

Welding, Casting, Covering

asting complete on 1, elt brscket on, control sticks done, cast 2, cover front seat bottoms and backs 1800 lunch?

With one aileron balance tube done, the second was easy. I’ll elaborate more on the process this time.

Here's the finished weight of the first lead tube. I will be able to drill some of the lead out once the aileron is covered to get a perfect balance.

I used a thick aluminum pan that Tabitha found at the thrift store, complete with a little pour spout. It was really perfect for pouring the lead.

I used tire weights that were really dirty. I would tilt the pan, and direct the torch at a tire weight. It was amazing to watch the bright silver liquid run out and leave the dirt, oxidation, and steel clip behind. A few passes with the torch helped be sure that all of the good lead was out. From there I would reach in and remove the nasties with needle nose pliers, putting them into a nearby rotel can. I would repeat this process until I had a fairly large puddle of bright lead, then I would reheat that puddle so that the whole thing was molten, and pour it into the tube. I would try to preheat the aluminum tube some too, in hopes that the lead would make it all the way to the bottom. Once the whole thing was cool and finished, I flipped it over and heated the other end. This caused all of the dirt and gravel to float up to the top, so I removed each of those with pliers. That left me with about a 1/4″ lip of aluminum as the lead settled into places that used to have little bits of rock in them.

I used a hammer to shrink the edge of the aluminum tube, so that it will help hold the lead in place more securely.

This would have been especially tidy if the whole tube was full, since then I could have the extra lead security on both ends.

Danny was telling me about an oil cooler that he didn’t use during his RV construction. Bob and others seem to think that it is adequate, and the price is great, so I think I’ll use it.

Oil Cooler donated by Danny

The control sticks are ready to repaint:

Here's the cap on top of the control stick, to support the push to talk.

I used the grinder to remove most of the weld bead around the control stick cap. This is to make sure that the grip will fit over the end, and this is certainly a non-structural piece, so I wasn't worried about removing the material.

I also finished the ELT bracket, except for cleaning and painting.

Here's the top of the ELT bracket, ready to weld to the bottom.

Here's the finished ELT bracket, ready to clean up and paint.

Today was a great productive day, and the weather was nice, so I figured I’d try a little bit of covering. I’m making the seat pans out of polyfiber covering, the same stuff as the exterior of the fuselage. The seats will be different from the airframe in that they won’t have any reinforcing tapes, UV protection, or color finishes.

I copied this idea from Oshkosh. The little cardboard disk helps reduce evaporation and drips.

Here's one of the front seat bottoms with the fabric on.

Today I finished covering the front seats, except for shrinking. I wanted to make this a priority so that I could get the seats ready for upholstery, which also involves cutting the foam cushions.

Posted on
Hours Logged This Session: 8
Total Hours: 1883.75

Back from Sun-N-Fun

It’s been a while since the last building entry, but I’ve been out of town more than usual. I just got back from Sun-N-Fun with a new list of ideas and a few new parts.

One of my SNF finds was these LED position lights. If I didn’t already have the aeroflash lights, I would have probably gone with a different setup, but since I do, I wanted to find some LEDs to replace the four incandescent bulbs. I had seen these before in the Aircraft Spruce catalog, and the guy who sells them to Spruce had a booth at the show. His price was a little better, so I got a set.

Here are the LED replacements for the position lights.

I took the cover off of the nav lights and took this picture.

Inside of the Aeroflash

This is the green LED in place

And the aft-facing white

Here's the whole assembly back together again. I replaced the green lens with a clear one, and was actually able to sell the original lens and bulbs to offset the price of the new parts.

On the red side I found that the gasket wasn’t properly installed you can see what I mean at the pointy end of the strobe insulator.

Notice how the black gasket doesn't quite fit right.

The white insulator wasn't quite right either.

When I put it all back together I put the gasket on correctly and also made sure that the white insulator was correct. I wonder if it came from the factory this way.
I realized that I should probably take some documentation pictures of the engine and accessories, because I always find myself with questions when I’m away from home.

The Starter...

...and the ignition wires...

...and the starter ring gear...

...and the carburetor...

...and the carburetor data plate...

I also found a baffle kit for sale second hand. This one wasn’t related to sun-n-fun, but I hadn’t had a chance to go through the kit to make sure that it was complete.

The plans for the Vans baffle kit are on one big sheet

There's all sorts of hardware in there

To change gears again, I finally had enough lead to fill the aileron balance tube. I ran safety wire from the corner of the bench to the tube, then leaned the tube slightly down and to the right as shown in this picture.

Aileron Balance Tube

This is a 1″ tube, which is larger than the 3/4″ tube originally designed in the plans. The diameter change is to improve the aileron if I recall correctly- it doesn’t really matter, since my ailerons have a 1″ hole in them. Back with the old 3/4″ tube, builders had to fill the entire tube with lead in order to get the required 5.5 pounds. I’m glad that another builder pointed out that the 1″ tube definitely does not need to be full. Without this tip I might have not thought about that until it was full of lead. I started to wonder if this uneven weight distribution would be a problem. I asked Bob, and he said to just leave the tube at it’s full length so that it will have more attachment points, and not worry about it. I’ll probably have to drill some of the lead out to actually balance the aileron. If I leave the 1″ hole open during covering, I will still be able to get a long drill bit into the lead. I can make small covers to pop-rivet over the 1″ holes when that is done. This will also come in handy if I need to recover the aileron later.

While I had the torch out, I figured I would also weld a cap onto each of the control sticks. This will make it much easier to mount a push to talk switch on the top. In this picture I’ve cleaned the paint off in preparation for welding.

Control Stick prior to welding

I also removed the paint for the ELT bracket

I don't remember where I got the idea for this holding fixture. It is 16 gauge copper wire and alligator clips. For tacking it works well, but since the clips are soldered it might not hold if it gets too hot.

Posted on
Hours Logged This Session: 5.3
Total Hours: 1883.75

ELT Antenna Bracket

Today I was in the mood for some welding. First, I noticed back when I primed the headrests that I had missed a problem with one of them. I had started to cut one of the horizontal tubes, then realized that I was cutting in the wrong place. This left a scored line around the tube, so I wanted to grind the paint off and run a bead around that score mark to remove the potential stress riser.

Fixing a problem with one headrest

Next, I needed to make a welding cart to hold my tanks. I started with this cheap harbor freight hand truck and spent an hour or so modifying it. I didn’t count this time towards Bearhawk building of course.

Starting point for a welding cart

With the tanks safely secured, I started on that ELT bracket.
Note: I’ve since removed this bracket and found a better way to do the same job. The problem that I encountered with this installation was that the fairlead fit a little too loose in the fairlead tube, and there wasn’t much clearance for the antenna feed connection. The better method that I came up with was to use an aluminum sheet piece on top of the stringers.
I started with the tube that will hold the fairlead plastic, and a short piece of tube that will locate that tube vertically.

Even with as much practice as I have, I still am not a pro. Note how I didn't get out fast enough with the torch at the edge of that thin 7/8\

My goal was to try and locate the top of the antenna plate just below the level of the stringers, just in case the covering had a little bit of sag between them. The reality is that since the stringers are so close together at that point, the covering probably won’t sag at all.

The ruler is just a straight edge to hold the bracket blank level with the stringers.

Here’s the blank after I’ve bent it. It’s going to be a tight fit with a 90 degree BNC adapter to keep the coax out of the elevator trim cable’s way.

ELT antenna bracket view from the top

Here's the top half of the bracket

Posted on
Hours Logged This Session: 3
Total Hours: 1883.75

Cable Guards and More Parts

Today I spent some time going through a big order of parts and hardware. This order included lots of stuff, including the rest of the screws for the wing inspection panels.

Bearhawk Wing Inspection Panel Screw Organization

This is my organization method for the wing inspection panel screws. Each panel gets one compartment. Can you guess which ones are for the fuel tank panels?

Dad was in town, so he cut out some new strips of aluminum for the aft section of the rudder cable guards.
Deburring with the scotch brite wheel

Dad deburrs the new cable guard blanks on the scotch brite wheel (which he gave me for my birthday).

I also ordered a foot of 7/8 .035 4130 to make fairleads out of.
Fairlead Tube

A new fairlead tube for the ELT bracket

Here’s where the new fairlead will go, just under the new ELT antenna bracket that I haven’t made yet.
Bearhawk ELT Bracket Fairlead

It goes here, mostly. This is the buklhead station aft of the rear cabin bulkhead.

Posted on
Hours Logged This Session: 3
Total Hours: 1883.75

New Goodies

Today I spent an additional 1.5 hours on the wingtip, but the more exciting news is that an order came in from Wicks.

Seat Foam

Seat Foam and Invisible Cat

I ordered some 5052 Aluminum to make fuel lines out of, along with some foam for the seats. My plan for the seats is to use tempur foam for the bottom layer for its shock absorption, then to use regular seat foam for the rest. Wicks had the best price that I could find on a 1″ thick green cushion that was big enough for the seats.

Here our quality assurance department verifies the alloy of the aluminum fuel tubing by smell.

I also got some rivets for the doors. They are made of aluminum and have a nice large head to help spread the load evenly. I’m planning to use these AN fittings for the fuel quantity gauges. They have Flared ends on both sides, and one side has a bulkhead attachment. My plan (for now at least) is to set up the fuel quantity sight gauges outboard of the fuselage frame, on the inboard side of the root rib. This will eliminate the need for any flexible tubing.

Rivets and AN Fittings

The Wicks price was pretty good on aluminum pull rivets for the door and window skins. The 90 degree AN fitting is for the fuel quantity gauge.

I didn’t want to use tempur foam for the entire seat cushions for a couple of reasons. Cost and weight were two factors, since the tempur foam had more of each. Another reason was the recommendation of a professional interior guy that gave a presentation about how to build seats. Another Bearhawk builder named Dave Lenart recommended Rochford Supply for the foam. The higher density option is 4526, with the softer 3319. The 1″ thick harder stuff goes over the tempur foam, then the softer 2″ thick stuff goes on top of that. The seat back is 2″ 3319 by itself.

Seat Foam

The seat foam cushions came from Rochford Supply

Cinnamon Roll

Foam Cinnamon Roll

Posted on
Hours Logged This Session: 1.5
Total Hours: 1883.75

Wrapping up the Belly Piece

Today I finished the aluminum belly piece, at least for now. I wanted to further test my wingtip strip technique, so I put in a few rivets.

Wingtip Rivets

I'm using the -4 rivets to fill the holes from the first round of wingtip screws, and the -3 rivets to fill the holes from the old rivets.

New Tools

Here's the results of an order from the Yard, thanks to a little Christmas money.

Aluminum Fabrication

I only had half an hour to work today, but I made up another aluminum attach/stiffener for the belly panels to join with. When I drilled the holes, it turns out that the angle piece wasn’t wide enough, and thus the edge distance from the rivets was way too small. See pictures in the next entry.

Aluminum Belly Panel, Left Side

Today I worked on installing the left side belly panel. It is the same as yesterday’s entry, but just on the other side of the airplane.

Left Side Blank

Here is the left side still as a blank.

Me Trimming

Here's a picture of me trimming the part.

Attach Angle, Take 1

Here's my first attempt at a piece to use for joining the two panels together. It is way too skinny!

Right Front Belly AL Panel

Today I was working on the new aluminum piece that goes on the belly just aft of the exhaust tunnel. I decided to remake these pieces because of some mismatched holes, and so that I could make the panel in two pieces. By making the left and right halves separate, I feel like I can have a closer fit around the landing gear shock struts, and I can add a dual-purpose aluminum angle joining and stiffening piece in the middle.

I started out by using the old one-piece belly section as a guide. I used .025 2024T3 stock to cut the flat blanks, then slowly started adding in the various perimeter shapes. I bent the very slight bend on my toy bench top brake, and then cut and trim to make the fit just right. Here are some pictures of the part clecoed in place.

From Above

Here is a view of the right side panel from above. The floorboards are out in this picture.

From Above Right

Here is another view from above, including the new aluminum side piece, which joins to this belly piece.

From Below

This picture is looking up from the left side.

The finished part

Here is the mostly finished part. It still lacks a joining tab aft of the landing gear hole, and hasn't been dimpled yet. I've been holding off on dimpling any of the boot cowl parts, since I'm still not entirely sure about how all of that is going to go together.

Trim and Debur Right AL Panel

debur aluminum

Here I am deburring the aluminum panel that goes on the right side.

Today I spent some time trimming the panel for the right side. The file seems to be quite effective, especially when I follow it with some 150 Aluminum Oxide emery cloth.

Welding Practice

I wanted to get in a little more welding practice and I needed to make a gift for our dirty santa gift exchange, so I made this guy out of some scrap materials:

Evil Creature

Evil Creature

It was the most evil-looking creature that I could create.

The Other Side

Welding the other side of the fuselage went much faster, and it turned out better.

New Steel Support in Place

New Steel Support in Place

I used a little rattle-can primer to keep the metal from rusting. I’ll replace that with some epoxy primer when the weather warms up, so that I can be sure that the covering process won’t lift the paint.

Steel Instead

I decided that I didn’t like the idea of using aluminum angle as the aft support for the panel that goes under the door. This was mostly because I couldn’t think of a way to attach the aluminum angle very cleanly, so I figured I’d try to make one out of steel. I would be able to weld the steel to the fuselage, making for a much cleaner attachment. I saw that Bob specified .032 mild steel for the bulkhead at the trailing edge of the boot cowl, so I used .030 for this piece. It took me a little while to get it cut to shape and to bend it on my little toy brake, but I was very pleasesd with the finished product. I bent the trailing edge also, partly to increase the strength of the part and partly to be sure that it doesn’t chafe the fabric.

The bottom is aluminum angle, the top is the steel before bending

Aluminum Angle on top, steel blank ready to bend.

Aluminum Angle on top, steel blank ready to bend.

Aluminum Angle on top, steel blank ready to bend.

I made a paper template of the flat piece before I bent it.

I made a paper template of the flat piece before I bent it.

I was a little bit worried about welding on the longeron. Making hangar doors is one thing, but welding on an expensive fuselage is another. I had a scrap piece of 3/4″ .049 (Bob’s T11) tubing like that of the longeron, so I started practicing. Since the tube is .049 and the tab is .030, it took a little practice to learn how to keep the heat off of the thinner piece. You can see the result.

Here you can see that the longeron sample tube is .049" thick compared to the .030 tab.  I wanted to practice dealing with this difference.

Here you can see that the longeron sample tube is .049" thick compared to the .030 tab. I wanted to practice dealing with this difference.

It looks pretty good in the middle, but the ends need work.

It looks pretty good in the middle, but the ends need work.

This is a bad one.  I started using narrower pieces just to make it harder.

This is a bad one. I started using narrower pieces just to make it harder.

Here is the end after trimming and ready to fit.  Note the clearance for getting the floorboard in and out later

Here is the end after trimming and ready to fit. Note the clearance for getting the floorboard in and out later

Here you can see the cleco side clamp holding the bottom ready for tacking.

Here you can see the cleco side clamp holding the bottom ready for tacking.

Here is the left side in place

Here is the left side in place

Here is the left side in place

Here is the left side in place

I used a 90 degree die grinder with a scotchbrite pad to remove the paint on the longeron and door sill, which was quite effective. In the end I was pleased with the welding, and now I just have to make the other side.

Optional Aluminum Panel

Here is the inside view of the panel.

Here is the inside view of the panel.

I had a surprise morning off from work due to some cancellations, so I spent a couple of hours working on a trailing edge support for the optional aluminum panel that goes under the door. I like the idea of using this panel for two main reasons. One is to make for a place to attach the lower strut fairing. The other is to protect the fabric in a high-traffic area. I didn’t really think of a good way to mount the aluminum angle support that the avipro manual describes. Some other builders have been able to figure out good ways to do it, so I picked up some 3/4″ angle and started working on making a piece.

Here is a mark so that I can trim the panel to match the other one next time I have it off.

Here is a mark so that I can trim the panel to match the other one next time I have it off.

Here I am working on it again.

Here I am working on it again.

The aluminum piece turned out nice enough, but I still wasn’t able to come up with a method of attachment that I liked.

Here is the end of the Aluminum angle.  I tapered it some to try and limit the bulge on the longeron.  The current shape still needs one more cut to allow the floorboard to be removed later.

Here is the end of the Aluminum angle. I tapered it some to try and limit the bulge on the longeron. The current shape still needs one more cut to allow the floorboard to be removed later.

Here is the angle rear support stuck in place.  I sort of missed when I cut the slot for the tube.  I don't really like it.

Here is the angle rear support stuck in place. I sort of missed when I cut the slot for the tube. I don't really like it.

This is a view looking up from the bottom.  The tunnel is on the left, and the aluminum belly piece is on the right.  I'd like to bend the aluminum piece a little bit differently so that it lines up with the tunnel at the trailing edge.

This is a view looking up from the bottom. The tunnel is on the left, and the aluminum belly piece is on the right. I'd like to bend the aluminum piece a little bit differently so that it lines up with the tunnel at the trailing edge.

Here is a shot of the panel that I was talking about earlier that I would like to rebuild.

Door Latches and Boot Cowl

I wanted to work on something other than the boot cowl for a little while, so I put together one of the door latches. I’m planning to use Bob’s design for the latch and will add some locks. I found some very compact cylinders at Home Depot for under $5 each. I got 3 that were keyed the same, just because I will probably not be able to buy more with that same lock again. Who knows, I might even use all of them. I also started looking at the optional aluminum panel under the door to see how that should go together.

Exhaust Tunnel and Barts RV

I only had a few minutes to work today, but I got the exhaust tunnel attached and the little pieces clecoed. Last night we went to visit Bart’s RV-8 Project. He had the whole EAA chapter over and cooked some burgers.

Brandon and Wesley look over the people hole while Wade looks over the luggage compartment.

Brandon and Wesley look over the people hole while Wade looks over the luggage compartment.

Bart explains the technical aspects of the flex-titanium jingle converter and other gadgets.

Bart explains the technical aspects of the flex-titanium jingle converter and other gadgets.

Page says that there are too many TV screens in there.

Page says that there are too many TV screens in there.

Jerry looks over Bart's RV

Jerry looks over Bart's RV

Bart’s project is coming along nicely and he’s going to put the engine on pretty soon.

Boot Cowl Head Scratching

I was fairly proud of the way the firewall turned out, so I started working on the boot cowl. Richard built the instrument panel top with a removable triangle panel so that the joint is on the inside of the windshield. Bob’s prototype is just the opposite, with the hole for the cabane struts cut from the forward end. I like Richard’s way better, if for no other reason than to keep rain from having a potential leak under the windshield. The top and large side pieces were easy enough to figure out, but when I started working on the small access panels and the tunnel it took a little bit more time to get it all figured out. The panel that goes behind the tunnel is one that I would like to remake, so I didn’t want to count on its holes for guidance. Bob attached the boot cowl with screws on his prototype, but my preference would be for rivets. I asked him what his thoughts were now that he’s been flying for 10 years and 1000 hours or more, and he said that he hasn’t removed the panels once. This was good news, so I’ll plan to use rivets. This is an especially easy decision in the context of the little removable panels that Avipro incorporated. If I take off those panels, the tunnel, and the front floorboards, I would have very easy access to anything in that area.

Quality Control and Pushrods

Today I spent most of the day working in the hangar and it was great fun.  I spent about an hour sorting out the dumped pile of hardware, and this was a good experience.  I got to be pretty fast with identifying the #6 and #8 nutplates.  I also started going through the wing counting hardware and checking on things.  I used the tackle box pictured in the last post to make an inventory of the #6 screws for the wing inspection panels.  There are 94 screws for each of the fuel tank panels… I sure hope I don’t have to take those off very often!

List of contents at the bottom of the tub, awaiting royalties from land o lakes.

List of contents at the bottom of the tub, awaiting royalties from land o lakes.

I also finished counting hardware for the floorboards and the rear bulkhead.  I put them into a butter tub and listed the requirements for each panel on the bottom of the tub. 

On the topic of floorboards, I disconnected the fuel valve and unhooked a few of the fuel lines.  The Usher gascolator is 3.75″ tall without the quick drain valve on the bottom, which means that it won’t fit between the floorboard and the bottom of the airplane.  It is nice to be able to keep the bottom of the gascolator above the bottom of the airplane for fire protection in the event of a crash that removes the landing gear.  I might try and find another home for the Usher and buy one of Bob’s gascolators since his is short enough to fit by the valve.  It looks like Richard’s solution was to put a quick-drain at the bottom of the fuel valve also.

I would like to do it differently...

I would like to do it differently...

I also spent some time working on the elevator trim tab pushrods.  I was concerned about the kinks in the bend, since they might pose as potential stress risers in service.  To address this concern, I considered replacing the entire part, but it made much more sense to just replace the bent section.  I got out the old AC 43.13 to see what it had to say about reparing tubing. I had a piece of tubing on hand that was larger than the 5/16, so I went that route.

Tubing repair with a larger piece per 43.13

Tubing repair with a larger piece per 43.13

I made the calculations using the diameter of the original tube.

Since the OD of the original tube was 5/16, it was easy to make some calculations about how much to overlap.

Since the OD of the original tube was 5/16, it was easy to make some calculations about how much to overlap.

Look, it’s really me working on the stuff!

Jared Yates building a Bearhawk!

Jared Yates building a Bearhawk!

It looks like a hungry fish!

It looks like a hungry fish!

Wait a minute, that's the wrong kind of fish!

Wait a minute, that's the wrong kind of fish!

That's Better!

That's Better!

Ready to Weld

Ready to Weld

Next time- welding.

Firewall Trimming Continued

Here is a bit more time with working on the firewall, with no substantial content beyond the last post. I just got back into town from a nice weekend of fishing, and while I was gone the firewall didn’t trim itself.

Fuel Systems and Brakes

Today I finished welding the elevator trim pushrods:

Before and After

Before and After

I also took an inventory of the fuel system and brakes to figure up which fittings I’ll need and how much line to use. I went back to read the Beartracks and realized that Bob recommended 5052 Aluminum lines instead of the softer and much cheaper 3003. I asked him about this and he said that he certainly prefers the 5052 because of it’s superior resistance to fatigue cracking, but that the 3003 would work fine too. He said that the 5052 was still quite workable in it’s -0 condition. I also asked him about a primer, and he said that it really wouldn’t be necessary. He used to add them to his airplanes early on, but he says now days he doesn’t even bother, especially on airplanes with an electric starter. He said that the accellerator pump used during starting can substitute instead.

Counting Bolts Again

Today I spent half an hour or so going through my list of bolts to buy again, this time with regard for the possibility of drilling our own solid bolts. It’s not very much time, but it’s all we could fit into the schedule today.

I did manage to dump out a little tackle box full of hardware, so next time I’ll have plenty to do.

Answering Questions

I called Bob today and asked him about the AN210-3A vs -3B pulleys. He said either would work just fine.

I also asked him about the braided fuel line, which is something I’ve been waffling about for a while. The issue is that the current fuel lines are braided stainless lines instead of solid 3003 aluminum lines. The braided lines are popular with the race car crowd, but they are about much heavier per foot than the same size of Aluminum wire. In fact, the weight difference of 40 feet of 3/8′ is 1.76 pounds for the AL vs 5.8 pounds for the stainless. I don’t have any doubts that the stainless tubing is up to the task, since the pressure ratings and chemical resistance are great. I am worried about the longevity of the rubber line inside of the stainless tube. Is this concern well-founded? Probably not, but I really don’t know. By using these lines does it mean that the fuel system will only last 132 years instead of 250? or does it mean that the fuel system will only last 5 years instead of 50? Racecars aren’t built for the long term- they are built to be reliable for short periods but not for long periods- but that doesn’t necessarily mean that the fuel line won’t still last for as long as I need for it to.

I have consulted several expert opinions about the tubing, so I figured I might as well ask Bob what he thought. To summarize, he said that it should probably be fine, as long as the resistance to auto fuel was good (which I would say it is). He added that it was much more expensive and much heavier and thus couldn’t imagine why anyone would use it instead of the AL. Richard’s point was that it was much easier to install than the AL tubing. If I were starting from scratch I would have stuck with the AL tubing, but since the stainless is already paid for, cut to length, and installed, I will probably stick with it for now.

Hardware Patrol

Today I continued my hardware patrol.  I have been through the entire fuselage and the control stick and have replaced and/or noted what I’ll need to get to continue.  I can definitely justify the expense of a drilling guide since I have lots of bolts that are good candidates for drilling for cotter keys.

I changed the bolt on the trim wheel to one with a hole in the shank and feel much better about it.  I removed the doors since the hinge bolts were a little bit too short.  Rather than just swapping the bolts I just took the doors all the way off so that I could get in and out easier.  I made a few bolt changes on the elevator and flap controls to account for length and/or drilled bolts.  I also went through the landing gear bolts and installed the ones with the correct grip length, now that I know how to do that.  I didn’t have the proper drilled bolts on hand but I’ll have the gear off several other times and can replace them next time.

Using the torque wrench for the first time on the Bearhawk

Using the torque wrench for the first time on the Bearhawk

I like to keep the chainsaw handy for deburring aluminum and notching 4130.  Not really!  I also managed to dump out the little tackle box full of nutplates and washers.  I picked them up but haven’t sorted them back out yet.  I’ll probably try to use household tubs with tight fitting lids since the clear tackle boxes don’t stay segregated very well.  Either way it’s a waste of productive building time and I should try not to do such things.

Nuts and Bolts

Comparing the M4 to the Bearhawk

Comparing the M4 to the Bearhawk

This morning started out with a morning of Young Eagles flights.  I got to see Buck’s Maule M-4 for the first time.  He flew 8 of the 31 kids, which was pretty amazing considering that he only had 2 seats.  He said that the max gross weight is 2300 and the useful load is about 800 pounds.  He has the same engine that we will use, though we probably won’t have the same Hartzell CS prop.  His airplane is certainly beautiful, and I can’t wait to finish ours since it will be a very capable young eagle hauling machine.  For now I just helped out with the paperwork and logisitics.

Filing the Brake Pedal to fit between the tabs

Filing the Brake Pedal to fit between the tabs

In the last entry I was starting to install the right side brake pedals when I realized that I was going to need to relocate some tools from the clubhouse.  I loaded up my home-made work bench and took it over to the hangar, complete with an assortment of tools that I will hopefully not need in the clubhouse as much as I will need in the hangar.  I had to file the attach side of the pedals a little bit so that they would fit between the attach tabs.  

I started to mount them but realized that I didn’t have the right bolts.  I have several little boxes of bolts but was surprised that none of them were the right length!  Actually, I did have several that were the right length, but they were not drilled.  Since the brake pedals and cylinders are subject to rotation, 43.13 states that they must not be secured with self-locking nuts- that means a drilled bolt with a cotter key.  Since I knew that I was at least going to need those bolts, I figured I might as well go through the rest of the airplane and see what else I will need.  Shipping from the aircraft hardware stores generally isn’t free or even cheap.

"Reserving" the hardware anywhere that I can

"Reserving" the hardware anywhere that I can

I also started to notice that some of the bolts that I had were already comitted to parts and assemblies that were temporarily removed from the airplane.  For instance, the bolts that hold the flight control cables onto the control horns were not on the airplane, but were presumably in some of those little boxes of bolts.  I made a sweep of about half of the fuselage, adding missing hardware as a way to mark it as “reserved.”  In the process, I also saw some hardware that was not installed the way that I would have installed it, so I also resolved those minor conflicts.  For instance, the rudder stop bolts weren’t really quite long enough to stick through the nylon lock nut, so I switched them out. 

The longer bolts with 1, 2, 3 threads showing.  Correction- there shouldn't be any bolts here at all.  The rudder travel is correct without any bolts.  If it was not correct, the way to adjust the travel would be by tapping the holes and threading larger bolts from the front to back.

The longer bolts with 1, 2, 3 threads showing. Correction- there shouldn't be any bolts here at all. The rudder travel is correct without any bolts. If it was not correct, the way to adjust the travel would be by tapping the holes and threading larger bolts from the front to back

This was the case in several areas, and I also saw a few “subject to rotation” applications that I would have prefered to use with castle nuts and cotter keys.

This bolt should have a castle nut and cotter key per AC 43.13

This bolt should have a castle nut and cotter key per AC 43.13.

This bolt is too short since it doesn't have a thread protruding through the nylon.

This bolt is too short since it doesn't have a thread protruding through the nylon.

I worked for 3 hours today and made notes of which hardware I was definitely going to need, which included a few small pieces, and a few big ones, like the engine mount bolts.  I was somewhat surprised to see that I didn’t have any of those, since I figured that they would have been part of the Wicks hardware kit.  So, I went to the Wicks hardware list to look and see if they were originally included.  There on the list are some AN6-46 bolts, which are about the right length and in the right quantity (5).  So either the wicks list has changed, I have the bolts somewhere else, or I don’t have them.  I repeated this same process a couple of other times, referencing the Aircraft Spruce catalog for the grip length of each AN bolt, measuring what the grip length needed to be, and sorting through drawers to try and find the right stuff.  All the while I was making a list of things to buy so that I can make one order and get most of what I need.

I have several bolts that are the right size but undrilled, so I might try and find a bolt drilling jig.  For example, I have enough -6 bolts for the landing gear that I will probably not need anywhere else.

I also noticed that on the plans Bob calls for a pulley as AN210-3A, which is equivalent to MS24566-3A.  Yet, the wicks kit included only -3B pulleys instead of the -3A’s listed on the plans.  So far I haven’t resolved this discrepancy.  The Aircraft Spruce catalog says that the -a and -b pulleys are the same dimensions but have a different type of bearing in the center.  I suspect that they are interchangable but will probably have to call Bob or someone else to figure that out for sure.  The funny thing is that in a case like this I picture an attorney questioning a witness.  “Why didn’t you use the pulley specified in the plans?”  Maybe that’s an idea for the next episode of Law and Order.  I know it’s terrible to think of it that way, but that is the image that comes to mind in this case, and also quite often at work.

Some folks say that building airplanes isn’t as hard as people make it out to be.  This is quite likely true, and an experienced airplane builder can certainly separate

Organizing and Inventory

I’ve spent a few hours this week unpacking, building workshop infrastructure items, and taking inventory.  I’m almost done adding shelves, racks, and work tables that I’ve made out of leftover building materials.  One large corner rack is enough to store the ailerons, flaps, horizontal tail pieces, and most of the other parts. 

Since Richard had not yet ordered an engine mount I requested one from Mark at Avipro back in September and just now got around to unpacking it.  I was a little bit surprised to see that it had a fifth mounting lug, and I started to wonder if maybe it was actually a mount for the 540.  It turns out that they started adding the fifth leg on the 360 mounts too, so it was the right one.  I should add that I’ve been very pleased with the support that I’ve gotten from Mark, even though I wasn’t the one who wrote him a big check.  I asked him about getting a set of brake pedals for the right side in hopes that I would be able to catch up with him at Bob’s Picnic tomorrow.  It turns out that he wasn’t going to be going to the picnic but was glad to send me some for a small charge.  While I was unpacking I found that Richard had a set already, so I had to call Mark to cancel the request.  Anyone who can put up with that kind of trouble is worthy of respect and gratitude.

While moving the small boxes with hardware from the trailer I spilled a few of the drawers and had a handful of mixed hardware.  I spent some time sorting through all of the drawers and making sure that the labels matched the contents.  I certainly don’t want to buy hardware later that I acutally had in the wrong drawer. 

I’m getting to the point now where I won’t have any excuses not to work on the airplane!  I’ve spent several hours reading Richard’s Log and the Avipro Assembly Manual to try and see where we are going to start.  I have several good starting points in mind and have also made a list of “things to be sure to do.”  Likewise I have a list of “things to buy.” 

Today I also installed a few flourescent light fixtures to help combat the shortening daylight hours.  I’m sure that the guys from Alaska wouldn’t have any sympathy for me there.

Putting the Fuselage on the Landing Gear

The hangar is almost done, and the poor airplane has spent most of the summer in the trailer.  When we get ready to move it out of the trailer and into the hangar, things will be much easier if the fuselage can sit on its own feet.  It took a little bit of time to look over the plans and locate the bolts, but now it’s all done.  There is quite a difference in height with the airplane on the landing gear, especially with no weight to stretch the struts.  Now it’s taller than I am, and it is easy to see why Richard wanted to take the gear off for working in his garage.

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Hours Logged This Session: 1.1
Total Hours: 1883.75