Service Letter SL-00014

Time: 4 Hours

Yesterday Vans aircraft came out with a new service letter that applied to the RV-8. It appears they have had some completed aircraft have issues with the skin on the sides of the fuselage at the very tail end. The problem stems from rapid turns on the ground while hitting bumps causing a side load to the skin. The few aircraft had some creasing of the skin in the affected area. So Vans came up with a fix which adds a piece of angle aluminum riveted to the skin at an angle. This helps carry the increased stress of side loads. There isn’t a requirement to complete this step but recommended. When I got up this morning we had already planned on moving the fuselage over to the paint shop.

I asked the painter if he would mind me working on the fix while in his hangar and he didn’t have an issue with that. His hangar is only a block away from our house/hangar so moving tools back and forth wasn’t an issue. The install was pretty straight forward and allowed me to buck some rivets which I hadn’t done in a while. I didn’t take many photos as it was hot and I didn’t want to stop working so I wasn’t in the painters way. He spent most of the day laying out the left wing paint masks and figuring all his measurements.

Here is a look at the two angle pieces I created and in place on the outside of the skin for drilling purposes. Once they were all done I cleaned the edges and primed them before riveting them in place. I’m glad this service letter came out when it did and I could complete it before the painting started.

Heat Shield’s Sealed

Time: 1 Hour

The Thermo-Tec heat shield needs to have its edges sealed to prevent any fluids from being absorbed into the matting that’s under the foil. One of the options is to use 3M aluminum foil tape. Aircraft Spruce sells it in various widths, I decided to use the 1.5”. Applying it was easy, just cut to length and press to seal. I did round the corners to match the matting corners to make it look more aesthetically pleasing.

Cowl Heat Shields

Time: 2 Hours

Once the lower cowl was sealed with the Rhino 9700 I was able to start adding the heat shielding. The fiberglass is close to the exhaust pipes and the heat they produce. Untreated and the cowl can heat up enough to to bubble the paint on the exterior. There are various products one can use to shield the cowl from heat, I used a product called Thermo-Tec which is a 12” x 24” adhesive backed liner that consists of a fireproof material covered in a foil like reflective material. I started with a couple of paper templates that I taped to the inside of the car and put it in position with the engine. I made several changes in order to make sure I had good clearance on either side of the exhaust pipes on the left and right side of the engine cowl. After I had that complete I use the templates to cut out the shapes and the actual material. Are used some denatured alcohol to clean the newly sealed cowl and applied the Thermo-tec material after removing its protective back layer. The adhesive allows for you to move it around slightly before applying pressure to make it stick permanently. It is also easily manipulated around complex curves and corners. The last thing to do is decide how I want to seal the edges of the Thermo tech material, either with aluminum tape or high temperature RTV.

Cowl Sealing

Time: 4 Hours

I found out that my measurements for the engine cowl were spot on once I was able to install the propellor. That was a huge relief as there are several moving parts that affect how the cowl sits and going by just measurements was a little scary. I was now feeling comfortable in finishing the inside of the engine cow which consist of sealing the fiberglass and installing heat shielding. I decided to use a product from Rhino linings called Rhino 9700. This product is used by composite airplane builders to line the inside of their fuel tanks. It is a two part epoxy coating that drys to a glossy light grey. The process is pretty easy, clean the cowling, mix part a with part B and apply within the 25 minute time period. You should only mix enough that you can apply in that timeframe as it starts to set up fairly fast after that. Are used a small paintbrush and a foam roller to apply, it didn’t make it perfectly smooth but it was close enough for the inside of the cowl and my needs.

It is dry to the touch in 6-8 hours and fully cured in 7 days. Now the cowl will be protected from oil, fuel and any other liquid in the engine compartment.