Sunday, April 01, 2007

Avionics Upgrade - Part 6

Now that we have the parts removed, the next step in the project is to prep the exposed pieces for final assembly. This section will included covering the parts with leather, removing paint, powder coating, etc. It is important to start this step as soon as possible. It can take quite some time to get the parts back from the third-party finishers.

Leather Work
In my opinion, there is nothing better than the feel of fine glove leather -- especially on the control yokes. However, leather work is more of an art than a science. It isn't something that most owners can do on their own. It takes time, skill and precision to cover parts in leather. This is something that everyone that is in 36G will see and likely touch. It has to be right.

I looked around for quite some time to find a company to cover the yokes and glare shield. I wanted to find someone that does this fairly frequently. I didn't want them learning on 36G. I discovered Aero Comfort in San Antonio Texas. They are a well known aircraft finish facility. They work on all GA aircraft, but their bread and butter is complete interior restoration of corporate aircraft.

The above picture is from Aero Comfort's website. It shows the steps required to cover the yokes. The quality of their work is remarkable. The stitching and construction is second to none. They also add padding to make the parts a joyful experience to hold onto for hours. They can also do leather embroidery. 36G's project will have a stitched old Mooney Eagle on the center cap. They will also provide the switch lettering for areas that need it (e.g. Map Light, MIC Button, etc).

Custom leather is expensive; however, there are alternatives that can greatly reduce the cost. Most shops that do custom interiors for cars, buses, boats, etc. can most certainly do this type of work. The only thing to keep in mind is that the materials used in a certificated airplane need to meet FAR burn specifications to be legally installed. The person doing the work does not have to be an aircraft mechanic. In fact, many upgrades of this nature can be performed by the owner/operator. What I suggest doing is to buy the materials from an aviation interior suppler and have a local skilled craftsman do the work. This way you know the material meets the burn specifications. You do not want to take chances in this area. Materials that don't meet these specifications can ignite and fill a cockpit with toxic smoke in seconds.

Refurbishing the panel
The panel pieces are the next step in the process. 36G like many older aircraft has aged paint that needs to be refurbished. The key to creating a panel that looks new is to completely strip the original paint. Scratches or any blemish in the surface will be visible if the prep work is not completed properly.

Removing old paint, of course, is much easier said than done. It is a lot of work to strip the paint without damaging the material. The process for removing paint on aircraft panels is the same as removing it from the aircraft. You need aviation approved paint stripper. Aircraft Spruce and other aviation parts suppliers sell what you need to do this. NOTE: Paint removal products are considered hazardous material and can only be shipped via ground service. I recommend ordering paint removal products well before starting the project. Under no circumstances should you use chemicals not approved for aviation use. They can weaken the panel causing cracks and failures down the road. Don't even think about using non-approved strippers. Take your time and do it right.

In 36G's project, I also need to fabricate some filler pieces that will be installed above and below the right radio stack. If you recall from my earlier writings, the second COM radio will be mounted even with the top of the GNS430 to its left. This will be about 3/4" from the actual bottom of the stack. The filler panel above the right stack is also a bit longer since I will not have as many radios installed as before.

Fabrication of aluminum is fairly easy. You need a shear to cut the straight lines, an assortment of files to do the close finish work and a drill for the mounting holes. NOTE: Most FBO's have a shear that they will let you use if you don't have one. The trick to using a shear is to go in knowing they do not cut exactly perfect. What you do is get close to the line you want to cut using the shear and then file the rest to get a perfect fit. Another trick is to use the old piece as a template. In 36G's case, the width and the screw holes are exactly the same. The pieces were just a bit taller. All I had to do was trace the old piece onto the new and add the extra material needed. Tracing materially reduces the time it takes to fabricate the parts and virtually guarantees that the new pieces will fit during final assembly.

After the pieces are clean and fabricated, the next step in the process is to finish them. Standard painting techniques apply to these pieces like any other part of the airplane. You Zinc Chromate, sand, paint, sand, etc. until you get the finish you are going after. In 36G's case, however, I want a permanent scratch resistant finish. Panels tend to get bumped around and I want to make sure she looks as good as new for many, many years to come. The modern painting method is to use a powder coat finish, which is basically a plastic powder sprayed onto the parts that when heated melts and encapsulates the pieces with a hard laminated finish.

Sears Hardware and other suppliers sell the equipment to do powder coating, or you can take it to a shop that specializes in professional finish work. I chose to use a professional finisher since they have significantly better equipment than I do. The total cost for 36G was $150, which is well worth it.

Color selection is another key factor that must be taken into consideration. If you choose powder coat or traditional paint there are a million colors to choose from. The key to picking a color is to find one that can be easily matched it in the future. You can certainly mix it later, but my preference is to pick a color that can be matched with off of the shelf spray paint. It is a pain to mix paint in order to finish a screw head! In 36G's case, I picked a DuPont semi gloss white finish powder coat that is nearly an exact match to Sherwin Williams Krylon 1502 canned spray paint. I like matching to Sherwin Williams or other large paint chain because they are accessible throughout the world and have strict quality control. Sherwin Williams also makes Jet Glo and other high-tech aircraft finishes.

Custom Redwood Accent Pieces
The final finish work preparation in 36G's Extreme Makeover is to fabricate the wood accent panels. In my opinion, wood really sets off a panel. Wood is used in nearly every high-end application -- especially in cars, boats, corporate jets, etc. To do 36G right, wood needs to be incorporated into the design. I found that this was much easier said than done. Most wood shops cannot create the custom pieces required for an overlay. They need to be precision cut and laminated in order to meet FAR burn specs. At EAA AirVenture Oshkosh I found a company called Aero Enhancements that specializes in this type of work. The owner is Steve Dunning and he does amazing work. They can create all sorts of pieces including ones that are internally lighted. They have refined a process of taking thin cut real wood veneer that is used in cabinet making and sealing it. The end result is a waterproof, fire resistant overlay that is beautiful.

The key to making the wood pieces, however, is to cut them so everything fits perfectly. Most Aircraft panels were made by hand. The holes, lines, etc. are not perfect. When you create a wood overlay it needs to fit exactly. Fit is especially critical for 36G's circuit breaker panel. Every hole has to align perfectly. To accomplish this, the original pieces must be completely removed and digitized using AutoCAD or other vector based software. Aero Enhancements has the equipment needed to do this work, but it takes time to get on their schedule. I chose to do most of it myself using AutoCAD for the digitizing and Adobe Illustrator for the silk screened lettering placement. NOTE: if you don't own the equipment to do this type of work, most larger city's have drafting shops that can either do this for you or you can rent the equipment. Kinko's also has the Adobe products installed on machines you can rent by the hour.

The final product is a digital image of the pieces that are loaded into a computer controlled router. The silk screened lettering is also computer generated and printed directly onto the wood prior to cutting. The end result is a precision cut piece of wood that fits perfectly.

We are now complete with the prep work and the pieces are sent out to the vendors for finishing. Next on the agenda is rough wiring the avionics and preparing the aircraft for installation.

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