Windows and Plumbing

Starting to work on a lot of the small finishing projects on the fuselage.  A small piece of 0.060 Lexan was cut from the sheet that will be used for the doors.  Two triangles were cut using the templates provided by a fellow local Highlander builder,  A vibrating multitool was used to cut the shape and then the edges were polished with sandpaper.  Using the holes in the fuselage window opening, the mounting holes were drilled and a cleco was installed.  The holes will be upsized later for 1/8" aluminum rivets and the holes in the Lexan will be oversized to allow for expansion.

Inside view of Window

Lexan Cleco'd in place

Work has started on the brakes as well.  The current plan is to use the provided nylon brake line up to the Grove landing gear.  The plan also includes using stainless-steel braided teflon hose from the gear to the brake caliper.  Fittings were added the brake master and slave cylinders.  Nylon hose was installed between the master and Slave cylinder.  We ordered a Matco parking brake valve from Aircraft spruce.  Two holes were drilled under the seats that will allow the brake lines to connect to the Grove gear. Grommets were installed into the holes and two runs of the nylon hose were passed through and conected to the fittings in the gear.

Master & Slave Brake Cylinders

Grommets Installed

Brakes Lines Installed

Brake lines attached to Grove Gear

The Rotax fuel pump needed to be moved from its previously installed location.  Due to fuel line hose constraints, the  fuel pump needed to be moved about 2 inches or so further away from the Andair gascolator.  A new mounting bracket had to be made.  Actually the new bracket came out much nicer than the first version.

New Pump mounting bracket

Pump Placed on New Bracket

Hours: 20

Bonus:  Ed and Mike pulling the fuselage out of the garage before a painting session.

Header Tank and Fuel System work

 After modifying the header tank, I decided to paint it to make it look nicer.  I taped off the inlets/outlets, thoroughly cleaned the aluminum, and then primed it with an epoxy primer.  After that, I sprayed a few coats of gloss black and it looked great.

Header tank painted

Unfortunately, after installing it temporarily in the fuselage and mocking up some of the fittings, I found an interference issue with some of the inlet hoses.  The tank was mounted a little high and needed to drop down about an inch.  The mounting brackets are welded on which made it more of a challenge, but this was fixed by cutting/grinding a slot in the mounting bracket and hanging it under the V-shaped bracket in the fuselage.  This dropped the tank about an inch, and the bottom mounting bracket still lined up nicely.  Still need to widen one side of the slot a tiny bit more to ensure better clearance from the vertical tube, but that is straightforward.  And of course, in the process of doing this, I scratched the new paint job pretty good in a few spots, so I'll have to do some touch up painting later.

Top bracket modified and tank fitted

Header tank temporarily installed for fitting

Quite a bit of time was also spent planning the fuel line routing aft of the firewall. We are planning on using aluminum line for long runs from the header tank to the fuel pumps, and for the return fuel line back to he header tank.  Connections between the aluminum hard line and other fittings will be done with flexible hose so that vibrations during flight will not affect the system.  We will use larger 1/2"  with 8AN fittings from the wing tanks to the header tank as was recommended by Rotax for the fuel injected 912is, and 3/8" line with 6AN fittings will be used from the header tank to the fuel pumps and for the return line. 

Instead of standard rubber hoses for the various connections, we opted to use some hoses from Jegs (Pro-Flo Extreme) that are lighter and more suitable to fuels that contain ethanol.  The hoses cost a bit more, but still much cheaper than the other alternative of Teflon lined hoses.

In the process of planning, we found an issue with our planned routing between the fuel pumps and the gascolator which made it hard to meet minimum bend requirements for interconnecting hoses. Several options were considered to fix this, and the simplest was to move the fuel pump further from the gascolator which will be detailed in another post.  Hours: 19

Fuel system work, landing gear covers

Made a small modification to our header tank to optimize the fuel return for our fuel-injected engine.  We welded on another AN6 bung a little further down from the top of the header tank which allows us to locate the fuel return a bit lower.  This allows any returning fuel vapor to cool and condense before rising and venting to the wing. 

After welding, a 24 hour pressure test at 9psi was run and it lost a little pressure.  With soapy water, I found a slow pinhole leak.  The pinhole was welded closed and the tank was retested.   This time it held pressure for 24 hours, so the problem was fixed.

Pressure test on header tank

Planned out some of the fuel line routing, and installed a fuel shut-off valve.  

Two mounting brackets and a tray were fabricated for mounting the Rotax fuel pumps.  The tray was riveted to the brackets and the brackets were installed with Adel clamps.

Fuel pumps installed

A few small nose-gear spacers were painted gloss black, and the nose gear was reassembled.

Two covers were also created to enclose the landing gear holes in the bottom of the fuselage.  The back edge required a slight bend to match the profile of the fuselage.  Holes were drilled to match the existing nut plates that were previously installed in the lower support tubing. These came out looking nice.  Hours: 24

Aluminum cover for landing gear (2 were made)

Panel Planning

 Due to several fuselage support members behind the panel, Mike decided to use FreeCAD, a open source 3D CAD program, to approximate the cockpit area around and near the instrument panel.  After lots of back and forth trips with a tape measure and calipers, a "good enough" 3D drawing of the area was accomplished.  Time: 4 hours

FreeCAD Highlander Cockpit

Painting small parts

 We continued with some painting, finishing up with a 2nd coat of orange on the gear leg, fork, and rear cover plate.  Afterward, there were a few small blemishes that were touched up and then buffed once dry.

Orange gear leg, fork, and rear plate

We sprayed a coat of gray on one side of the kick panels (which were previously primed), and sprayed a coat of vestal white on the other side.  A portion of the kick panels will also be painted orange, but we will wait until later because the cowl will need to be completed first to ensure the paint lines match up.

The baggage door was sanded and is ready for a 2nd coat (that part has no orange). Hours: 15

Back side of kick panels

Coat of white on baggage door and kick panels