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.

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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.

Fitting the Cowling (Part 2)

Time: 0.5hr

I just messed around with some ideas to mark the cut line. I thought maybe a bright light inside the cowling would let me see the edge I need to mark, but it only works in a few places. So far the only thing that seems reasonable to do it to measure from say the center of the rivet in 9mm (that’s where the edge is) and mark it then run some tape to connect the marks.

I found that putting some 6mm wide paint stir sticks between the cowling and the spinner flange makes it a lot more manageable. The sticks hold the gap (TAF says at least 5mm gap) and the cowling doesn’t want to move all over. I think I need to cut the right side a bit first since the engine is at a slight angle the cowling needs be cut a bit of an angle to match. If I take some material off the right side then I should be able to angle it a bit more, just need another millimeter or so.

Pretty much lined up.

Adding in the paint sticks really help hold everything in place.

The rear edge is marked, not a lot has to come off. Tomorrow I can cut it and start to fit the top halve.

Fitting the Cowling (Part 1)

Time: 2.5 hrs

I started work on fitting the cowling. The first step is to fit the top and bottom half together. One side fit well and went rather quickly. the other side took quite a bit longer and still had a bit of a bulge in the rear portion, however after fitting it to the fuselage the bungle went away so all is good. Prior to putting the halves together I taped the bottom half to the fuselage just to see how it would fit. Once that was situated I place the top halve on. I found that the left air inlet needed to be trimmed to fit around the alternator. I did a rough trim and tried to keep as much material as possible, but quite a bit needs to be removed. I will still need to do more work on this area, but I wanted to get it so the top could be moved around enough to fit it to the fuselage.

Joining the two halves was fairly straight forward. One side took quite a bit longer than the other. After the fitting seemed reasonable I measured in 55m from the front of the cowling and 11mm up from the seam and drilled a 2.5mm hole to put in a small cleo then it was 284mm for 2 more holes (the manual says 28.4mm, but I think they mean 28.4cm). And for the last hole I went a little shorter distance (275mm) because I notice the hole would be too close to the end of the inside flange and I wouldn’t be able to install the camloc socket.

After the halves were together I put them onto the fuselage. Wow what a nightmare trying to get it lined up. It’s really a two man job. At one point I had everything lined up nicely and then noticed the whole cowling was turned a bit too much to one side. Gently trying to twist it into position resulted in all the tape coming off and the cowling becoming completely misaligned again. So then back to square one. This preceded to happen a few more times and I think I used just about all the curse words I know. Finally I have it pretty close now and am happy with the alignment. The next step is to mark the top halve along the fuselage to cowling join and trim it. Now I just need to figure out how I’m going to do that. You obviously can’t see the edge of the fuselage through the cowling so you can’t simply mark along that line. I’m thinking maybe if I measure the distance between the fuselage edge and the row of rivets in the fuselage I can then use that measurement to mark the cowling on the outside. I’ll have to give it some thought.

It was getting dark so I couldn’t take photos of the final fitting of the joint halves on the fuselage. I’ll have to add some more photos tomorrow.

That’s not gonna fit. This inlet will need to be cut back a bit so it fits past the alternator.

Just seeing how things are going to fit. I noticed that if you get the bottom opening (near the nose wheel gear) lined up then the top edges are a bit off, so it’s one or the other, but you can’t get the bottom centered and the top equal on both sides. I think I’ll have to fudge it a bit.

left inlet opened up so it will fit around the alternator. I think I had to remove a bit more after I did the fitting with the halves joined.

 

EGT Sensors and Fuel Lines

Time: 1.5 hrs

The new EGT sensors came a few days ago and today I had some time to fit them. I think the new sensors will work better. These have a shorter lead so I purchased some K Type wire to extend them. they are also a bit easier to remove since the bolt holding them in is separate from the sensor body so you don’t have to turn the whole sensor (including the leads) to get it out. The only thing I don’t like as much is that the sensor has a 90 degree bend and so I can’t route the wire the same way I had routed it with the old sensor. I think they may work better on the front mounting holes, but from what I read the rear holes have a bit more accurate reading so I want to keep them in the back. I think the way I mounted them should work OK. I don’t want to take too much of the bend out of them in fear that I’ll break it.

NOTE: I thought I had a photo of the installed EGT, but I guess not. I’ll take one tomorrow and upload it.

The other thing that came were the fuel lines. Wow these are excellent quality fuel lines. Steve even used the blue fire sleeve that I wanted. They usually use the orange type of sleeve. I think all the lines will fit fine, the only ones still in question are the ones that screw to the fuel pumps since I don’t have those built up yet, but it seems like they will all work. I’ll come up with a more detailed install of the fuel lines when I actually do the install.

The new EGT sensors have an adapter that screws into the M8 thread and then the sensor bolt screws onto the adapter. I used some high temperature anti-seize (copper color) on the threads so that they don’t rust up and are hard to remove. I don’t know what the torquing on these should be so I just got them reasonably tight.

The new EGT has a much shorter lead so it will be easier to replace it if I have to. These are made by MicroFlight (Micro-1000)

The EGT has a 90 degree bend and I didn’t want to take the bend out. Think this will still work fine running the wire up between the cylinder heads.

A short of the fuel lines running between the firewall and the gascolator and fuel pump location. These will need to be torqued and secured.

All the fuel lines in and out of the FT-60 seem to work as well. I need to make a proper bracket for the FT-60.

A few photos of the -4AN line running from the tee (connected to the fuel regulator) into the fuel flow sensor. You can also see (in the upper photo) the short connector hose that feeds the tee from from the fuel regulator.

The -6AN return run has a special banjo fitting that Steve made. You can’t buy a stainless steel 10mm Banjo to -6AN fitting anywhere, you can get aluminum one, but not stainless steel. I’ll need to get a photo of it when I do the install of the fuel lines.

Top Front Skin and Dash

Time: 3.5 hrs

Today I finally got the top front fuselage skin installed. I think I’ve taken care of most of the items that need to do with the firewall and wiring so I think it’s safe to put on the skin. I’m sure something will come up that would be easier to do with the skin removed, but hopefully that will be at a minimum. I used some sika on the top join to seal it and also ran a bead down each side along the cowling join area. I had a few holes that were a bit tough to get lined up, having the wet sika there made it especially fun.

I also started to line up and drill the mounting holes for the dash. I think I have the dash in the correct spot. I know Craig M had some details on mounting the dash, unfortunately my dash has some funkiness on the tabs that makes measuring a bit difficult. I set the right side to to 20mm that was stated in Craig’s blog and that seemed pretty good, I then used a level to set the left side (the side with the weird cut) and drilled out a few holes for the 4mm rivets,. I’m going to wait on the rest until I make a faux panel out of some 1/8″ plywood. I want to be sure that when a panel is mounted that the center section is in the correct spot and the panel sits flat. The dash is pretty floppy in that area and it could easily be bend back and out of shape and then when I mount the panel it won’t sit correctly.

One finish up task before installing the top skin was to run this safety cable on the turbo server. It is just there to make sure the cable can’t pull all the way out of the server. The Rotax manual doesn’t show how to do this so I improvised something.

All looks pretty good so I should be OK to close it up.

All done. There’s a thin bead of sika along the front and I put some sika in the front join between the top skin and firewall.

Dash is lined up and started to drill a few of the mounting holes. I’ve got a bit of work to do on the dash itself and there’s quite a few things that need to be done with the avionics before the dash can get mounted. NOTE: I noticed that the flange on the dash on the right side is a bit large then the flange on the left so you can’t use that to judge if the dash is on straight.

Fits OK on the center console as well, but I’ll make a faux panel out of some thin plywood just to make sure it will all work OK. Next project is to fit the cowling.

Oil Pressure Sensor and Grommet Covers

Time: 2.0 hrs

Today I wired up the oil pressure sensor. This is one of the sensors (or senders) that comes with the 914. Rotax even supplies a pre-made 2 conductor wire with a 3 way Delphi GT150 connector on it, however I chose to run my own Tefzel shielded wire instead. I had found some 3 way connectors on Amazon that looked like they might work, but it seems like the pins just didn’t line up exactly. I then found the exact connectors on eBay which I installed today. I’m wondering why the wire is only 2 conductor since the sensor has 3 pins. The Garmin manual also shows a 2 conductor wire that connects the signal and 12 volts and then a resistor that taps off the signal to ground the sensor on the GEA24 side. The Rotax manual states that the sensor grounds itself via the engine block.

I also install two grommet protector covers. The covers are stainless steel and help protect the grommets in the case of a fire. I’m using syntectic rubber grommets and they really should be the silicone (red) type grommets, but I’m not able to find those type of grommets in the correct sizes I need. I know they make them, but I’m not able to find a source where I don’t need to purchase 5000 of them.

Additionally I finally installed the 90 degree connectors on the wires for the 2 GPS antennas. I was a bit surprised that they were solder type… sometimes Aircraft Spruce doesn’t have very good descriptions of their items. In any case even without install instructions I managed to figure out that I needed to solder them and got them installed and did a quick test with the meter to make sure there were no shorts.

The selection of Delphi 3 way connectors. The first (left) is the original one that came with the engine. I found the next (middle) one on eBay and the last (right) was the one I thought would work that I found on Amazon. The eBay one was pretty much an exact replacement and fits fine.

Pinning the connector is simple. The water tight seal is incorporated into the crimp so you just need to remember to fit that in prior to crimping.

I installed the 2 grommet covers. One on the hole I made for the fuel pump wiring (lower left) and the other (behind the engine mount, upper left) that installs on the grommet for the brake line. Since I used rivnuts to secure the covers to the firewall I also made a gasket out of silicone so that the cover would seal tight against the firewall. The rivnuts lift the cover up a little bit so just want to be sure it’s sealed. I’ll use 2 more of these on the split plate I made for the main wire pass through of the power and sensor wires.

So I have one more small thing to do and then I’ll put the front top skin. I’m hoping I can get that done tomorrow and maybe fit the dash. There’s still a few things I have to do to the dash and I’d like to install the avionics that are mounting to the rib first. Also I believe I need the interior side covers installed before I can install the dash. I’m hoping the interior will be shipped out from SA in the next few weeks.