More Cowling Work

Time: 3.5 hrs

Over the past few days I finished up (well it’s never really down, Is it?) work on the cowling. I had purchased a sheet of thermo insulation to put on the lower cowling under the muffler/turbo charger area and a few other places where the exhaust gets close to the cowling. The idea is to reduce the temperature so that no damage occurs to the cowling or paint. The thermo shield it good up to around 550 degrees Fahrenheit and provides a few hundred degree reduction in temperature, also I will be wrapping the exhaust so that should help reduce the temperature under the cowling as well. The thermo sheet is pretty flexible and was fairly easy to install. I will probably go around the edges with some clear RTV to seal up the edges and reduce any fraying of the fiber glass that makes up the thermo sheet. Prior to putting on the sheet I sprayed the whole inside of the cowling with high temperature silver paint. I didn’t spend too much time making it perfect. I just wanted it to look a bit more finished and maybe help reflect a little heat as well.

I also finished installing the doors and top air vent. I used some sika on the top air vent so that it seals up… yeah I know water is going to come through the slats, but no need to have more water than necessary.

Top air vent riveted and sika sealed.

Sprayed the inside of the top and bottom cowling with high temp silver paint. It came out OK. Didn’t want to get too caught up into trying to make it perfect. I think it looks better than the natural fiber glass though and the silver paint may help reflect a little heat as well.

A few photos of the thermo sheet installed. Mainly under the muffler and turbo charger area, but I also put some in areas where the exhaust gets close to the cowling.

The cowling is pretty much finished. Install the doors and camlocs. I’m pretty happy with the way the doors came out.


Cowling Work and ALT2 Relay

Time: 2.0hrs

Today I fit the top vent and doors on the cowling. I need to do some sanding on the doors to get the gap equal all around and to get a little better fit. Tomorrow I’ll spray the inside with high temp silver paint and I have a sheet of heat shield that I want to put on the bottom cowling. I didn’t have the hinges for the cowling doors so I had to make up some out of some extra hinge material I had.

I also finished up the install of the ALT2 (internal alternator) relay. I drilled a few holes in the relay mount and harness so I could safety wire them together and then wrapped the join with some silicone tape. I also sealed the wire entry points with black RTV.

Hopefully that will keep it from falling off. It’s on there pretty good, but you never know.

All sealed up and safety wired and mounted back onto the bracket.

Finished fitting the top vent and doors onto the cowling. I need to drill out the door rivet holes to 1/8″ (3.2mm) and do a little sanding to the doors. I had to heat one of the doors with the heat gun at 600 degrees to get it to bend a little more for a better fit.

The air vent fits well. I’m thinking of using some sika on the join so it seals up.

The doors line up pretty well. I need to do some fine tuning and also install the cam locks.

FT-60 Fuel Flow Transducer Bracket

Time: 1.5hrs

I made up a fairly simple bracket for the FT-60 Fuel Flow Transducer. I originally had just a temporary L shaped bracket and I was going to just replicate that in some thicker aluminum, but after looking at how close the aft mounting hole of the FT-60 sat to the bend I decided to make it a little more complex and extend the flat portion of the bracket by making a cut pretty much up the middle of the bracket so I could bend out a small section on top. I also made the bracket a little wider than the original and made the height adjustable. I noticed also that the bottom mounting screw hole so that it will slip over the screw (that mounts the Rotax 3-way solenoid to the airbox. I did this because it’s almost impossible to put that bottom screw back in with the bracket on. Now only the top screw needs to be removed (and the bottom loosened) to get the FT-60 bracket on. The only thing I have in question is that from a little more reading it seems that you’re not supposed to have a 90 degree bend in the fuel line within 6″ of the FT-60 and I have like 3 of them. The TAF way only really has one (coming off the fuel pressure regulator). I guess I’ll need to do a test to see how actuate the FT-60 is in this arrangement. If it’s not I can always reroute the fuel line to loop around rather then using the two 90 degree fittings.

I’ll be writing up a complete step by step on how to install the fuel lines and what fittings go were when I do the fuel line install.

Here’s the layout of the bracket. I cut out a 2 1/8″ x 4 ¬†3/4″ piece from a sheet of 0.09″ 6061 aluminum.

A few photos of the bracket. I notched the bottom hole so it can slide over the mounting screw. And I also made the mounting holes adjustable to accommodate the short hose run.

Side view of FT-60 on the mounting bracket.

After facing view. The bracket uses the same mounting screws as the 3 way solenoid that mounts to the airbox.

Top view

Faux Panel

Time: 1hr

Today I made up a faux instrument panel out of some blackboard material from Home Depot. I wanted to make sure that the dash had something in it before I finished drilling the holes in the fuselage to mount the dash. I won’t actually be mounting the dash for a while. I will probably use the faux dash to position other things like the choke and heater cables so that I can cut those to size. Now I need to figure out how to somewhat accurately drill the mount holes in the faux panel so I can screw it into the dash.

Once I had the faux panel in the dash I used a laser level to make sure the dash was level. I uses the heater outlets as a reference and measure on both side the same. The outside flanges of the dash aren’t equal between the left and right sides. I noticed this in some factory photos, but it should be OK since the fiber glass band that gets sika sealed to the fuselage after the windscreen is done is quite wide and will cover it.

Fitting the Cowling (Part5)

Time: 3 hrs

Well I think I pretty much finished the fitting of the cowling. There is still a few more things that need to be done like put on the access doors and the cooling fins, but most of the hard stuff is done. Today went fairly well. I had received the longer camloc studs from Skybolt which all worked fine except the -5s for the two in the very front of the cowling (under the cooling holes). I tried -5s and also -6s and even those seemed too short. I need to investigate what’s going on, even -4s “should” be long enough so I’m at a loss as to what’s going on there.

The part that I thought was going to be difficult, drilling the holes for the camlocs along the firewall join, ended up going pretty quick. If I did it over I think would have been best to not drill out the existing 8mm holes to 5/8″. I did this on most of the hole and only had a few left that were 8mm, but it was easier to match drill the 8mm hole and then drill the cowling out to 7/16 and the mount strip to 5/8″. The ones that I previously drilled out to 5/8″ I had to watch closely and adjust with each step of the step drilled to make sure it was staying centered with the hole in the mount strip. I uses a mirror inside the cowling to verify. All the holes came out to be very accurately drilled and the use of the floating camloc receptacles made the mounting of the cowling come out pretty good. I have one spot on the top right of that cowling that I’m not happy with and the very bottoms stick out a bit. I’ll see if I can improve those areas, but they don’t Bother me too much. Most of the gap around the cowling is between 1/32″ – 1/16″ so I’m happy with that.

Got the top 2 camlocs in. A pretty good fit on the top. I had put some reference marks to locate the holes for the camlocs.

This was one I could match drill to 8mm. This was much easier then doing the holes that I had drilled out to 5/8″

All camlocs are in and things line up pretty well.

When the camlocs go in they push in on the cowling. In most areas it’s not that noticeable, but the bottoms stick out a bit because of this. I noticed if I bend the mount that is on the nose wheel with the 2 most bottom camlocs that it helps minimize this, but don’t want to bend it too much more. It doesn’t bother me that much since it on the bottom, but I’ll try to improve it at some point.

The gap behind the spinner is good as well, it’s about 6mm.

The left side is slightly wider (about 8mm) then the right, but it’s not very noticeable. This is because the engine is at a slight offset while the cowling is straight. I had tried to put the cowling on an offset to match, but it proved to be a bit difficult and I didn’t have enough material on the firewall side of the cowling to do it.

This one area bothers me the most. It bulges and  sticks up a bit. Since taking this photo I improved it a little by using the fluting pliers on the mount strip to pull the camloc mount down a little.

The cowling is finally on and held by the camlocs… no tape… YAY!

Another review of the cowling.

Left cooling hole cut back for alternator.



Fitting the Cowling (Part 4)

Time 2.5 hrs

More work on the cowling. I think I’m getting close. Today I installed the camlocs on the bottom bracket on the nose wheel and also on the join around the cowling. I had order mostly 4002 type -3 length camlocs and only 2 -4’s for the nose wheel bracket, but the -4 was too short for the nose wheel bracket and they worked perfect for the cowling join except the 2 in the front (I think I’ll need -5’s for that). So I have to order a lot more -4 length camlocs and I’m order a few -5’s and -6’s. I think the reason for the difference in length from what Mid West Sport had said was because I’m using the type of receptacle that has the movable center and I think maybe it’s a little thicker than the fixed type receptacles. I also found that a 5/8″ hole works well for the camloc receptacle side. It allows enough room for the collar and retainer ring to fit. I did drill out some of the cowling join holes to 11/16″ so that there was a little more room for the camloc to move around to get a better fit, but the hole is a bit too much. I was still able to get the 3.2mm rivets in but I would have felt better with a bit more material to hold the rivet in the fiberglass. I think it should be OK and it’s only on the 4 more center holes, but 5/8″ is definitely the better choice for the camlocs.

I purchased my camlocs from Skybolt, they’re a little expensive, but I really like the quality. I purchased stainless everything to help reduce any corrosion. They also have high strength titanium fasteners as well, but I figured it’s probably not necessary.

I was able to get a drill inside the cowling to drill out the bottom 2 holes for the camlocs. I made sure the cowling was lined up exactly where I wanted it and taped down the bottom edges to keep them tight to the fuselage. I then drilled a 1/16″ pilot hole as close to center as possible. I worked up to a 8mm drill to basically match drill the existing holes in the bracket. After I removed the cowling I step drilled the bracket holes to 5/8″ and installed the calloc receptacle. For the fastener side I step drilled the 8mm hole to 7/16″ and then used a hand realer to ream the hole until the collar fit and then used my debur bit to counter sink the edge a little so that the collar fits down into the cowling.

I step drilled the 8mm holes in the mounting strip to 5/8″. I’m not going any bigger then this and luckily it seems to be large enough for the calloc collar and retainer ring to fit into. I purchased some fluting pliers to flute the mount strip a bit. I think it will help the cowling edge seat down better. I noticed that the cowling bows up a bit on the top so hopefully fluting will help. It’s not really bad, but it could be better.

Got all the camloc receptacles installed.

So now I need to wait until the longer camloc fasteners come and the fluting pliers.

Fitting the Cowling (Part 3)

Time 5.5 hrs

I spent almost 6 hours today fitting the cowling and it still isn’t finished. I think this is worse than doing the windows… very frustrating to get right. I got a few tips from Robert Z., a few I had already figured out. The biggest help was using some 2″ tape to extend the fuselage edge (that is hidden under the cowling) out and then using more 2″ tape to lay over the cowling edge, but in line with the edge of the other tape. This gives you a pretty accurate cut line, but still needs a lot of fine tuning to get a tight fit. All that went fairly well, the part I thought was going to be easy is ending up to be the hardest. This is drilling out the holes for the camlocs. The reason why this is difficult is because you can’t get a drill inside the cowling to drill them from the inside (well maybe a few). And if these are off by even 1/16 of an inch the cowling isn’t going to fit well so they need to be exact. The manual says to remove the bottom halve and work on drilling out the holes for the top, but then the top part moves around and is pretty hard to keep it lined up well even if you tape it down. So I’m thinking maybe I’ll do the callocs on the 2 halves and then put them both onto the plane and then make sure all the pilot holes match for the other camlocs.

My other concern is that since I’m using camlocs then 8mm holes that are pre drilled in the mounting strip on the fuselage need to be drilled out to 11/16ths, but it doesn’t look like there’s enough material on the mounting strip to do that. I drilled a few out to 9/16ths and it looks like the collar will fit down into the mount, but I haven’t tried the retaining ring. Others say the camlocs work, so I’m hoping this will all just work out.

The red tape is aligned with the front edge of the fuselage so some is hidden under the cowling. This basically extends that edge out to where you can reference it.

The overlay the blue tape (probably would have been better to use a little more flexible tape, but this worked ok) and align the aft side with the edge of the red tape underneath. I then just used a sharpie to mark along the the tape edge. This is the cut line. I used a belt sander with 80 grit paper and took down the edge to about 1/8-1/16 of an inch from the line. then I use 200 grit paper on a block of wood to sand the edge where it was needed. I ended up taking everything apart a few times and went back to the belt sander because it was taking way too long to hand sand it. I also found that using a beefy tape for the base tape was good because it protected the aluminum when I was sanding the edge of the cowling in place.

I got a very tight fit. This will need to be opened up a little once I have the camlocs in place and everything is held more rigid. I know you want a tight fit here, but I’m thinking with paint there needs to be a small gap so that parts don’t rub and also the paint will add a little to the thickness.