Cowl Baffling, Oil Door, Baggage Floor, etc

Baffling:  To make sure all the air coming into the radiator opening on the cowl actually enters the radiator, we needed to create a baffle seal between the coolant radiator and the cowl.  The radiator provided by Rotax did not have any means to attach a baffle so an aluminum surround was fashioned out of 0.032 aluminum.  It was secured at the four mounting positions of the radiator.  Silicone baffle material was at attached with rivets and rivet washers.  The cowl was installed and the baffle material was marked so that it could be trimmed to fit.

Radiator surround and attached silicone baffle material

Side seal of baffle to cowl

Bottom Seal of Baffle to cowl

The shape of the oil door was tweaked a bit to match the curve of the cowling.  The hinge pin and spring on the oil door were then installed. 

Fuel filter placement was adjusted slightly to improve clearance from the boot cowling.

Baggage Floor:  Two separate thin (0.02") aluminum sheets that formed the baggage floor needed to be modified due to other changes that occurred during fabric covering and fuel routing. Some of the edges were trimmed to prevent interference with the fabric, a hole for the fuel drain was enlarged.  Also, another hole in the floor (no longer needed due to a change in our fuel routing), was patched.

Rear baggage floor with riveted patch and larger hole for drain

Clamps: Four standard Adel clamps (black) were replaced with silicone clamps (blue).  They have a higher temperature rating, but are also the better choice for holding the silicone hoses that they are clamping.  Hours: 15

Blue silicone clamp now holds this silicone hose

Cowl modifications, fuel site tube, brakes

Michael continued with the cowl modifications to improve the transition to the propeller spinner and also improve the area where screws will be added near the cowl air openings.  Lots of sanding, filing, and epoxy work was involved, but it's looking good.

Michael doing some filing work on the top cowl

The brakes continue to give us some problems.  Thought we had them all bled, but realized the left rudder pedals seemed a bit mushier than the right, and a few days later saw some large bubbles migrate from the pilot's right rudder pedal into the clear tubing.  Air seems to be staying trapped inside the right brake cylinder on the pilot's side.  So we will attack this again later, but will be using a new technique suggested online which involves removing that cylinder and changing its orientation during the bleed process to help the trapped air escape. 

We also installed a NACA duct on the right side of the lower cowl.  This allows us to have a good dedicated air path to the Rotax regulators, as the B-side regulator is known to have issues if not cooled properly.  This regulator is attached to one side of the Rotax fusebox, which is located in the middle of our firewall where airflow may not be the greatest.  We are also planning on adding a larger heatsink to this regulator which will help with the cooling.   If later testing (during the summer) shows that this extra air is not needed, then we can use the duct to provide cool air directly to the engine, so it won't be wasted. 

NACA duct on lower cowl

A shroud for the header tank site tube was fabricated from aluminum, then primed and painted.  I'll be adding a diagonal hash pattern to the tube which will sit directly behind the fuel site tube.  Due to the refraction of light going through fuel, this makes it much easier to see the actual level of fuel.  

Hours: 12

Aluminum site tube shroud after a coat of paint

Misc (Brakes, Cowl, Header Tank)

We've been working on a lot of various parts over the last few days.  We finally got all the brake plumbing complete and got the brake fluid bled. It took some effort to remove all the air bubbles.

The front of the cowl received 3 layers of fiberglass over the foam shape in near the propeller.  After allowing the epoxy to cure a lot of sanding was done to smooth the transition.  We're planning on adding fasteners on the inside of the cowl air openings hear the propeller hub.  This area needed some attention with fiberglass to give enough room for fasteners.

To make the site tube more visible on the header tank, Ed is fabricating an aluminum shroud that will also have a hash pattern that will greatly improve the header tank level.  This is just a back-up since we also have a fuel level sensor on tank that turns on a red LED on the dash if the level ever drops below a set value.

Hours: 8

Peel-ply over the top of the fiberglass addition on the upper cowl

Fixing the lower cowl to allow for fasteners

West System epoxy in use

Ed working on header tank site gauge shroud

Brakes and Cowl 2

Ed continued working on the brakes.  The two master cylinders were removed and rebuild kits from Matco Mfg were installed.  Ed had to fabricate an assembly jig to help with the installation.

Ed installing one of the rebuilt master cylinders

Michael worked on the cowling modifications.  After allowing the glue to setup overnight, the cowl was split and reinstalled on the airframe.  With the aid of a homemade jig and some spacers the foam was sanded down to give the spacing needed making sure the face was parallel to the propeller hub.  Once the spacing was correct.  The shape was filed and sanded.

Foam sanded into shape

Testing with propeller spinner

Hours: 4

Brakes and Cowl

Finally getting back in the swing of things after taking a break over Christmas. 

Brakes: After some more adjustments, we no longer have brake fluid leaking from any of the fittings, but are having issues bleeding the brakes.  The right brake has air infiltrating into the lines somewhere around the passenger-side cylinder. Also, the left brake was bled but over time has gradually been getting some air bubbles in the lines near the left master cylinder.  After attempting several times to bleed them without success, we suspect some of the internal brake cylinder seals are leaking, and perhaps sitting on the shelf for 8+ years before installation didn't help.  We bought Matco brake rebuild kits and plan to replace all the seals on the brakes before bleeding the brakes again.  

Draining brake lines in prep for additional work

Cowl: With the prop installed on the airplane, we are not happy with the aesthetics of how the front of the cowl lines up with the spinner.  Because of this, we're going to do some fiberglass cowl modifications to make this look better.  It may reduce drag a bit too, but probably not much.

Gap between spinner and cowl on pilot side

We are gluing some styrofoam to the front of the cowl which we will later shape and use as a form for laying up the fiberglass.  Hours: 10

Foam glued to front of cowl