Cowl Lip Baffles

Time: 4 Hours

The last part of the baffle puzzle are the lower cowl lip seals. These get attached to the lower inlet lip of the lower cowl and create a seal against the inlet ramps on the left and right sides. The idea is to shape strip of aluminum to the shape of the inner shape and use it as a clamping surface to squeeze the seal fabric in place. I worked the right side first and bent the strip to the shape making sure that it had a “clamping effect” to the sides. I then cut a piece of the 3″ wide seal longer than needed to start with. I then laid out three screw hole marks for the screws that will eventually hold them in place. I then drilled the three holes in the cowl flowed by match drilling through the cowl into the aluminum strip under. I used these holes and marked the seal fabric so I could punch holes it the fabric as well. With all three parts now having holes in them I attached them to the cowl. The fitment is just a rough shape at this point and need to be trimmed to fit better. I decided on 1″ as my overlap which should be sufficient. I marked 1″ marks along the entire cowl lip for cutting. I removed the cowl and the baffle and trimmed along the marks I made and put it all back together. I’m supper happy with how the fit was after trimming. I put the top cowl in place to see how the fit was and it ended up very tight and should provide a pretty good seal. I repeated the process on the left side. I returned the baffles to the forward center section as well as the forward sides and installed the top cowl. Here is how they look and I’m pretty happy with the fitment. The left side doesn’t have rounded corners due to the air filter placement. In the corners there is a little gap that will allow leakage.

I removed the lip baffles and drilled, deburred and riveted nutplates in place for #8 screws. I’ll install these once all the cowl work is finished up.

Oil Door Hinge Pin

Time: 1 Hour

While waiting for some fiberglass to cure on the lower cowl lip I decided to fabricate the hidden oil door hinge pin. The door is hinged on the top with a hidden bracket. To hold the bottom of the door I decided to use another piece of hinge. I installed these a long time ago and had planned on how I would remove the lower hinge pin to allow the door to open. The upper bracket has a spring to it so when the door is unhinged it springs open. So I had fiberglassed a aluminum tube with the same inner diameter of the hinge itself to the inside of the cowl to direct the pin as it’s inserted to the first hinge eyelet. I used the hinge pin to mark the firewall where I needed to drill a hole for the pin. I used a dab of orange torque seal on the tip of the pin and slid it through the hinge eyelets until it touched the firewall and left a dot of torque seal identifying where to drill. After removing the cowl I drilled the hole and clean the edges as the stainless steal is very sharp after drilling. I returned the cowl and slid the pin to make some marks for where to cut and bend for the handle I was planning on forming. With the cuts and some bending I made what I think will work well. I put some shrink tube on the handle side to keep it from scratching and make it easier to hold. I only have to pull it out far enough for the door to open and check the oil. Then while oblong the door down I slide the pin in and the door is secure. I made the handle long enough so that it can be tucked next to the nylon block for the baggage door lock. This will keep it from spinning around in flight and the baggage door itself will prevent the pin from sliding out of position.

Fuel Pump Overflow

Time: 1 Hour

The engine driven fuel pump has an overflow port to allow excess fuel drain after engine shutdown. Van’s uses a 90° elbow that has a soldered 1/4″ copper line on it. When I was installing it the copper line broke off. So I decided to upgrade to a AN842-4D elbow. This has the 1/8″ threaded side and a 1/4″ OD barbed side. I could then use some 1/4″ ID hose to run from the AN fitting to some 1/4″ aluminum tube that directs the fuel overboard under the fuselage. I cut some tubing and made the required bends so that it exits underneath the fuselage through a hole I drilled. I then secured that tubing with adel clamps. With the AN fitting secured in the pump all I needed to do was cut a length of tubing to connect the two. I will use zip ties to secure the hose to the tubing and AN fitting.

Alternator Blast Tube

Time: 2 Hours

Not required by PlanePower but it doesn’t hurt to have cool air blowing on the cooling fins located on the aft portion of the alternator. I had drilled the hole on the right hand inlet baffle ramp a long time ago so I would have to drill through the painted product. Now I just needed to figure out how to get the tube situated to blow air on the right spot. What I decided on was to fabricate a bracket that would allow it to be riveted to the alternator aft cover and hold the tube in the right position. So I took some measurements and cut out a blank from .040 sheet aluminum and formed up the bracket. I drilled a 3/4″ hole for the tube and match drilled four holes for blind rivets. Once I had the shape and all the bends looked ok I cleaned it up and primed/painted it to match the baffles. Once it was dry I riveted it in place and installed the tube. I drilled two holes in the end of the tube that allows a small zip tie to be installed at the top and bottom of the tube and secure it to the bracket so it doesn’t come loose. I then installed the aft cover now with the bracket and measured for the opposite end and made the cut. There is a third zip tie securing the tube to the alternator as it comes forward and keeps it away from the exhaust pipe. I also drilled two small holes on the bottom at the lowest spot of the tube so that any moisture that were to get in the tube would drain out and not be directed at the alternator. It’s simple and secure, I think this will do a good job of cooling and was an easy project.

Sniffle Valve

Time: 1 Hour

At the bottom of the engine is the Superior cold air sump. This is where the air that comes in from the air filter/servo gets divided up and sent to the individual cylinders. During engine shutdown there can be a very slight chance that unburnt fuel travels back down into the sump. AeroSport power said this is very rare in a fuel injected engine but still recommended the sniffle valve. The valve is a mechanical means to drain any fuel out of the bottom of the sump. The valve is heat activated, or the lack there of as heat actually closes the valve and when it cools it opens allowing any fuel to drain. I was pretty straight forward installing the valve and I just needed to extend the line so that it would exit past the lower engine cowl onto the ground. I used some MIL-6000 hose to give it the bend and flexibility and secured the other end with a clamp to the engine exhaust bracket. I’ll replace the clamp with a high temp one after I get it from Aircraft Spruce. I think I will also put some eat shields on the exhaust where it’s close to the hose.