Exhaust planning, fuel line work

The front right exhaust currently interferes with the radiator placement, so we plan on rerouting that part of the exhaust to fix this.  Michael used his 3d printer to print up some straight pieces and bends so that we could make a mock-up of the exhaust routing first.  The pieces didn't snap well together, so we used some tape to hold it together while experimenting.  We came up with a relatively simple routing that bumps the exhaust out a bit to go around the radiator (The radiator is not installed in the picture below, but the radiator bracket is in place).  Exhaust parts were ordered, and I've been practicing some stainless welding in prep for this part of the project.

Mock-up of right front exhaust

Two holes were drilled in the firewall for the fuel inlet and outlet, and bulkhead feed-through fittings were inserted.  Due to the thinness of the firewall, two aluminum spacers (1/8" thickness) were made to ensure the nuts held these fittings tight.  A  T-shaped bulkhead fitting was installed to allow for a restricted bypass that is required by the Rotax 912is.  Hours:12

Fuel outlet in firewall (engine side)

Fuel fitting on back side of firewall

More Lower Cowl Work and Oil Lines

Continued working on the lower cowl modifications.  Additional Micro/Epoxy mixture was added to fill in the fiberglass weave and imperfections.  After allowing it to dry, it was sanded down.  The excess fiberglass on the inside of the cowl was removed as it was no longer needed.  A coating of filler/sanding primer was sprayed on the part.  This is VERY revealing and immediately highlights the imperfections.

Lower cowl lookng nice

Excess Fiberglass removed on interior

Filler/Sanding Primer Sprayed

We spent a few hours planning our firewall penetrations and what would mount on or near the firewall.  This was needed so we can start progressing toward installing fuel and oil lines.

We plan to have an oil fluid thermostat in our system.  This will hopefully help keep the engine oil at a more appropriate temperature, also allowing the engine to warm up faster, bypassing the oil cooler until the temperatures of the oil are elevated.  A bracket was made and the oil fluid thermostat was installed on the firewall.

Two oil lines were built and installed.  The first one goes from the bottom of the Rotax engine and to the oil tank. The second oil line was run from the oil tank to the oil fluid thermostat.

Hours: 12

Oil flows out of the engine to the oil tank on the Rotax 912iS

Oil flows out of the oil tank to the oil fluid Thermostat

 

Lower Cowl Fiberglass work

More work was done on the lower cowl in preparation to fiberglassing in the the front openings.  The 2 part foam was shaped with a 1/4" radius front edge.  After removing the gelcoat, it was found that some large air pockets were in the original fiberglass layup so that needed to be repaired with filler. 

Lower Cowl Ready for Fiberglass

Three layers of  omni-directional fiberglass were epoxied in on the front cowl and a final peal ply was added.  After a 5 hour cure, the peal ply was removed.

Fiberglass added

Peal ply Removed

The coolant radiator was mounted and all bolts were torqued and cotter pins were added where needed.  We used Titanium M10 bolts on the main brackets to help reduce some weight. 

Hours: 10

Coolant Radiator Mounted

More Lower Cowl Modifications

 With the openings for the Oil Cooler and Radiator set we set out to make the openings a little more pleasing to the eye and a little more aerodynamic.  A mixture of epoxy, flock, and microbeads was added around the two openings and allowed to cure.  Using a 1/4" round over bit and a router the edges of the openings were eased over, giving a nice pleasing look.  

Oil Cooler and Radiator Openings with round over

Angled view of the addition

We also determined that we wanted to close up the cowl openings on either side of the propeller.  After much discussion we decided that just closing off the bottom cowl opening (ala Steve Henry and others) would be the easiest and quickest way to achieve this.  We bought some 2 part expanding foam and after taping off the area we wanted to fill the foam was mixed and poured into the area.  Now we've got to shape the foam so we can add some fiberglass fabric to finish the opening close-out.

Expanding foam added to cowl openings

Hours: 10

Lower Cowl Openings

After a lot of tweaking on the placement of the Oil Cooler and Coolant Radiator, we think we've finally nailed it down.  New brackets were constructed to mount to them to the engine.  Also, a single bracket ties them together.  Rubber shock mounts were added for vibration isolation.

Original bracket used to determine correct spacing

Final brackets installed

With the locations fixed.  The two cowl openings were planned.  We drew on the cowling the maximum size and placement of the openings.  We started with a 4" hole and slowly opened up the hole until we were happy with the size to hopefully provide ultimate cooling air into the two cooling devices.  Our plan is to glass in some curve edges to make the openings more aerodynamic and provide some strength to the cowl in the areas that material was removed.

Hours: 24

Cowl Openings

Another View of the Cowl Openings

Lower cowl mod, Planning for oil cooler and radiator

To aid in the cowl placement, we created a thin 1/4 inch circular wood spacer that is the same diameter as the spinner, and attached it to the prop flange.  This is used to set the spacing between the back of the spinner and the cowl. 

wood spacer attached to back of prop flange

We then trimmed the back edge of  the top cowl in order to get it to fit into place behind the prop flange, and then attempted to attach the bottom cowl to the top.  Found out we had another interference issue as the top and bottom halves couldn't quite meet up.  This was frustrating as we had followed the instructions and had performed the initial cut to a "trim line" that was provided. That's what we get for following instructions.

 Luckily, we still had plenty of overlap between the top and bottom, so we just needed to fill in a few holes, and adjust the bottom edge to line up with the top cowl.  We used epoxy mixed with flock for added strength, and later added a few layers of dry micro (epoxy with added glass micro-balloons) to smooth it out.  Some sanding was done between each step.

bottom cowl modified to line up with top cowl

We also trimmed the back edge of the top and bottom cowl so there is now a straight line along the back edge of both top and bottom cowls.

Currently, we are planning out the placement and mounting methods for the oil cooler and radiator.  This is tricky as there isn't a lot of room.  We have considered extending the lower cowling down to provide more room, and have borrowed some cowling pieces from a friend that has a newer Rotax 914 cowl that allows for this.   We haven't ruled this out, but are currently focused on seeing if we can squeeze in everything with the existing cowl first, as this would minimize the weight added.  

We created a few test brackets with slotted holes that allowed us to vary the placement of the radiator, and also created a bracket for the oil cooler.   We cut a foam block the same size as the oil cooler so that we could play around with placement easier.   The first thing we learned is that the exhaust outlet from the front left cylinder interferes with the radiator hose with just about any position of the radiator, so we may need to build a custom exhaust for the left front cylinder.  We haven't got this all nailed down yet, but we're considering our options.  Hours: 16

Planning out position of oil cooler and radiator

Panel and Avionics

 After many hours of laying out our panel in software, we got a builder friend who's also building a Highlander, to cutout a temporary panel in press-board on his Shopbot CNC.  A few issues were found in the cutout that will be fixed in the next pass.  With some minor tweaking the panel was assembled and placed into the cockpit area to check for interference issues.  None were found.

Panel minus Garmin G5

The transponder we chose for our project is the remote mounted Garmin GTX-45R.  The mounting tray for the transponder needed to be mounted in the fuselage and we chose to mount it behind the baggage area.  A WAAS GPS will also be needed to feed the transponder and a mount was also fashioned and attached to the transponder mounting bracket.

Transponder and GPS mounting bracket

Mounting bracket installed in the aft Fuselage area

Hours: 12

Cowl work, Drain valve, fuel site tube

We spent several hours making small incremental cuts on the top and bottom cowl, along with judicious sanding, in order to get the top and bottom pieces to fit together properly.  At first we didn't think they could ever fit, but the fit wasn't bad once modified.

Top and bottom cowl fit after trimming

Some brass elbow adapters and tubing were installed on the header tank for a fuel site tube.  Versilon SE200 clear tubing (from McMaster Carr) was used for the site tube as it has an inner liner that is resistant to ethanol.  

Fuel site tube

A drain line was also installed from the header tank to a fuel valve under the fuselage (for fuel testing or draining). Due to the shape of the fabric underneath, we were unable to use some of the parts from our kit, but we purchased a 1" brass bulkhead fitting (1/4 NPT) which worked well.  Also, an inline fuel filter was installed.  A filter here was recommended by several builders as it will catch any debris that could cause the fuel valve to start leaking.  Hours: 14

fuel drain line with filter

Curtis drain valve installed on bottom

Firewall trimming, Boot cowl drilled, fuel pump bolts

The boot cowl was fitted in place, then match drilled to the holes in the fuselage.  The lower edge was trimmed a little more.  With the boot cowl in place, we could then proceed with the firewall fitting.

The engine and engine mount were removed so that we could create a posterboard template for the titanium firewall.  After making the template, we laid it over the titanium firewall sheet, and trimmed it (with snips) to match. 

Template in place over firewall material

The firewall edge was deburred, and installed with clecos.  We left about a 1/4 inch gap between the top of the firewall and the boot cowling, and a gasket (provided by Just) will be installed on the firewall later which will fill this gap.

Firewall fits nicely.

Finally, the engine mount and engine were reattached. 

Firewall and engine attached

We also did a little work on the fuel pump installation, torqueing down the mounting nuts on the bottom of the fuel pump housing.  The aft nut was tricky to get to, but we found that by rotating the whole pump mounting bracket, we could get easier access to the rear bolts... and then refasten the bracket in place afterwards.  Hours: 8

Panel Layout

 After a lot of work on both the panel and wiring diagrams we think we've got our final layout.  FreeCAD was used to layout the panel in 3D.  This allowed us to check for behind the panel obstructions.  The COM radio (Garmin GTX200B) was the main item we had to worry due to some cross support tubes.  KiCAD was used to draw the wiring diagram (schematic).  This allowed us to know how many switches and circuit breakers to place on the panel.  Hours:20

"Final" Layout

FreeCAD: https://www.freecadweb.org/

KiCAD:  https://www.kicad.org/

Temp Engine Install and Cowl Fitting

We hung the engine on the fuselage which was a nice accomplishment, even though this is only temporary until we can get a template for the firewall made.  Once we have a template, then we will remove the engine and work on the firewall installation.

Installing the engine

In order to make a firewall template, we first need to fit the boot cowl, which is turning out to be a bit of an effort as we want to make sure everything lines up and that the positioning works with our aftermarket Dentz windscreen.

The cowling pieces are oversized so need to be carefully trimmed, then positioned carefully to get all the panels to line up.  We are making changes slowly as it's much easier to trim fiberglass than it is to put more back on.

Fitting the boot cowl

We also set the windscreen in place temporarily to see how it lines up with the boot cowl.  We'll have to do some more trimming along some edges of the boot cowl, but overall it looks decent. 

Fitting the boot cowl

Once we had the boot cowl where we wanted it, we drilled holes to attach it to the mount points on the fuselage.  After finishing this, we were able to install the cowl with clecos and take some better measurements to check it all out. Unfortunately, we found a few issues.  One was that our firewall is a little too short (about 1/2 inch) to reach the top of the cowling.  This is more gap than we want, so we are going to drop the cowling a bit.  The other issue was that part of the cowling was bowing out a little bit at the front corners.  Not a bad issue, but we want to improve it.  We epoxied over the holes we already drilled, and also added four small fiberglass spacers to the inside of the cowling to alleviate some of the bowing that occurs when fasteners are installed.

Lastly, we wanted to see how the exhaust fits, so we (temporarily) hung the exhaust and muffler.  Looked great!  This will also allow us to check how much clearance we have with the lower cowl.  Hours: 12

Hanging the exhaust system

Ring Mount and Waterpump

We bolted the Rotax ring mount to the engine, which was a bit more challenging than we initially thought it would be.  We had to remove the waterpump and a few hoses first.  And lining up a few of the the bolt holes, which are hard to access, while inserting tight washers was some fun, too.  But we managed to get the ring mount installed and torqued down to the engine.

Ring mount (white) installed

However, we had another surprise when we went to put the waterpump back on.  The inlet/outlet ports on the left side of the waterpump now interfered with the freshly installed ring mount.  So we called our Rotax Rep (Lockwood Aviation), and they confirmed that the engine as shipped from the factory did not have the correct outlet port configuration for use with the ring mount.  We needed a 20 degree elbow on the top left port, and the lower left port elbow needed to be rotated.  We ordered new elbows and a new waterpump gasket and waited for parts again.

Removing the two elbows on the left side of the waterpump was not trivial.  They have to be heated to at least 80 degrees C, and then rotated carefuly so as not to damage anything.  The waterpump is aluminum and works like a good heatsink.  We couldn't get the temperature quite hot enough with 1 heat gun, but we had a 2nd one on hand, and with 2 heat guns we were able to get it hot enough (The heat softens the locktite that is used to seal and hold the elbows in place).  Once the elbows were off, we cleaned the threads.

When the new parts arrived in the mail, we screwed on the new elbows temporarily until we could get them lined up properly.  We put the waterpump back on and rotated the elbows until we had them in the correct position, then we marked the position with a sharpie.  We removed the waterpump and elbows, applied a good coating of green locktite on the elbow threads (as recommended by Lockwood), and then screwed them back into place until they were lined up with the sharpie marks.  Then we let it sit for over 24 hours so it could cure.

Waterpump housing with 2 new elbows installed

We installed the waterpump with a new gasket, and then installed the coolant hoses.  It all looks good now, so we can move forward with the engine installation. Hours: 15

Ed installing the waterpump

Michael installing coolant hoses

Engine Mount, Pitch Servo, Schematics

We temporarily installed our new nose-gear engine mount see how how it fits, and while it was tight, it did fit.  We had to add a few washers behind the lower mount point, but this was not unexpected.  We checked the nosegear and it fit nicely.  The firewall was removed for now as we are planning on making a template to help trim the top of the firewall once we can determine how it meets up with the cowling.  

Temporary fitting of engine mount & nosewheel

Since we had the engine mount attached, we decided to see how the Rotax ring mount mates to it.  Unfortunately, we ran into a problem.  The shock-mount isolators (Large rubber isolators) that we purchased from Rotax didn't fit.  We contacted the factory and found that these parts were unique and we neeeded to purchase them from the factory instead of Rotax.  So we returned the Rotax parts, and are now waiting for the new parts to arrive from Just Aircraft.  So we are in a bit of a holding pattern for now until the new parts arrive.

One other thing we did was remove the pitch servo and change out 4 bolts that attached it to a mounting bracket (these were a little too long).  The new bolts were torqued, and the assembly was remounted in the back of the plane.

Pitch servo with new bolts

In the meantime, Michael has been spending many hours (days) putting together the schematics for the wiring using KiCad.  A lot of time has been spent digging through all the manuals to make sure we get the wiring correct, and much time was spent sourcing parts like switches, circuit breakers, etc.  Hours: 20  

Fuel lines and hoses

 Several flexible fuel hoses were fabricated on the supply side, including all the hoses between the header tank and the fuel pumps.  We used Jegs Pro-Flo Extreme hose which is a step up from standard synthetic rubber.  The hoses have good compatibility with fuels that contain ethanol (even supporting E85 fuel).  Not quite as nice as PTFE fuel hoses, but not as expensive, either.   Each hose is unique as the length of hose and type of hose-ends were specifically chosen for each hose.

Attaching a hose end

Fuel hoses to the gascolator and  fuel pumps

Fuel hoses to cut-off switch

A 3/8 inch aluminum fuel line was installed along the left side, running from the header tank to a spot near the footwell.  6AN tube nuts were installed and the tube ends were flared, as they will connect to fuel hoses with 6AN connectors.  

Return fuel line

Return fuel line runs

Lastly, another flexible hose was made to go from the 3/8 inch return line to the header tank. 

Hours: 12

Hardline to fuel hose connection on return line

Brakes and Panel

Finally got the parts in to finish installing the brakes.  We needed a 90 degree fitting on the landing gear and a straight fitting on the brake caliper.  The 10" hose fit perfectly and made for a nice clean installation.

Brake Line Installed

A lot of time was spent laying out the instrument panel and we're closing in on our final design.  We've started doing our wiring diagram (in KiCAD) and this will help us determine how many circuit breakers and switches we need.

Most recent Panel layout

Hours: 8