Cowl Flap Wiring and Heat Shield

Once the cowl flaps were figured out and installed I worked on running wires to them. The wires run along the inside of the engine cowling (think high heat, vibration, grease, fuel, etc) so the first thing I wanted to do was seal the fiberglass. I used straight epoxy and just spread it around the entire inside of the cowling with a squeegee. After the epoxy was dry I painted the cowling with some high temp engine paint. Now that the fiberglass was sealed I placed a heat shield material on the cowling in the areas of the exhaust.  

I connected the wires with small #4 screws and ring terminals. I then placed heat shrink around the connection.

The wires were then taped down using smaller pieces of the heat shield. I also spread some fire barrier caulk around the wires to help protect them against heat and wear.

Here you can see how the wires travel along the cowling under the tape.

Here is the finished product. The heat shielding is sealed around the edges. Also, you can see the connector for the cowl flaps in the top RH of the cowling. The connectors is placed there so its easy to disconnect the power and remove the lower cowling. With the compound curves the heat shielding was kind of a pain to install. I had to make a couple layers overlap, but I'm happy with the final product.

Started Cowling

Continuing to catch up on the posts so I'll just let the pics go through everything.

As you can see the cowlings don't line up very well from the factory. The whole section is really just about getting them cut to size and having everything match up in the end. The instructions seemed to do things backwards then the way I thought you'd do them. So after thinking things through I decided to just approach cutting and fitting these like a wood working project. After I got in that mindset things went really well.

One thing I should note is that I made the cut out in the lower cowling for the front landing gear leg much wider than what the plans call for. The plans dimension is so tight I couldn't even install the cowling over the landing gear. So I increased it by (I think) about 0.75".

So I couldn't use the table saw to make a nice straight cut like I would for building furniture, so I broke out the laser level to mark a straight line from the ridges of the inner circle to the outboard edges of the cowling openings. I used the ridges as a guide to know when I had the cowling level. I then trimmed down the outboard inlets flush to the lines that were made from the laser level leaving the sides sticking up to be cut later.

With the front edge cut the two halves of the cowl could rest against each other and I was able to tape them up into place. First I taped up the bottom cowl and got it into place. I used some spacers up front against the spinner and then just duct taped the cowling to the engine to suspend it in place. The aft part of the cowling rested against fuselage skin.I then used an edge finder, just like I did with the doors, to mark the edge of the fuselage onto the cowling. I then cut the cowling along the line and re-installed it with a few clecoes into the hinge to hold it in place. I re-taped in place in front around the spinner with spacer blocks. I then repeated the process for the upper cowling and after I cut it I placed it in position. The pic below shows how well the fuselage and upper cowl lined up. I wound up increasing the clearance between the fuselage and cowlings all the way around to about 0.10" or so.

With the cowlings clecoed in place along their hinges the upper cowl side overlapped the lower cowl. I made a straight line mark using a chalk line positioned at the leading edge joint and the aft edge point. You can see how the upper cowling was not perfectly straight.

The entire time I had a chunk of scrap wood that was the right in the middle of the clearance tolerances listed in the instructions. I had a large piece spanning the upper joint and several tapped in position (as shown in the picture) around the lower opening. You can also see how the cowling sits just below spinner. I've heard you want to have this because the engine "settles" in place and will drop a bit.

I cut the upper cowling and then used a large flat sanding block to really flatten the cut out. I then clecoed the cowling back on and used the upper cowling to mark the cut line for the lower cowling. 

With the two halves cut and sanded I had zero clearance between the two halves. So I had to remove the upper half a few times and sand it down just to create some kind of gap between the two. I then installed the horizontal hinges per the plans except a bit shorter to accommodate the Aerosport Pin Covers.

Everything lines up pretty well. The only thing I need to do now is some body work around the openings.

Engine Cowling: Vans Vs Showplanes

There are two engine cowlings available for the RV-10: the standard stock Van's Aircraft cowling and the Showplanes Cowling. Showplanes is a side company that makes parts for experimental aircraft. I am really undecided about which engine cowling I want to install when the time comes. So I thought it would be fun to ask you...the reader.

The Stats

Van's cowling
-Cheaper
-Ships with the rest of the finish kit
-Install instructions remain the same

Showplanes Cowling
-Requires larger more expensive spinner
-Improves cooling (although I have only heard this, I have yet to see any empirical data)

There is probably more points to be made, but I guess the ultimate question I ask is,

Which one do you think looks cooler?

This part is important! For those non aviation types the engine cowling sits right behind the propeller. Look closely at the engine inlets, the lower air scoop, or lack of scoop, the general shape etc..DO NOT LIKE OR DISLIKE BASED ON PAINT COLOR!    ...Have fun and feel free to leave comments.

Don't forget to vote at the end!

Van's Cowling

Showplanes Cowling

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