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.

Charge System Finish Up and Turbo Servo Install

Time: 3hrs

Today I ran some wires for the engine sensors and also bolted down the turbo servo. I also fabricated a simple bracket for the air that runs from the servo to the waste gate. Additionally I torqued down most of the electrical terminals (M6 terminals are torqued to 35 in lbs (5NM) as per the Rotax manual) and connected all the remaining connections for the charge system. I realized as well that I had use some nylon lock nuts on to hold the adel brackets together. Pascal remained me that you’re not supposed to use nylon locking nuts in the engine compartment because the nylon can melt and the nut will loosen. I will need to switch them over to AN363 all metal lock nuts with AN3 bolts instead of the M5 socket heads that I’m using right now. The funny thing is the nuts on the engine mount bolts (supplied by TAF) are nylon locking nuts so I wonder if I should get some M10 all mental locking nuts for those as well.

I was looking all over for the connector pin outs for the small connector on the back of the alternator. And as I sat there staring at the alternator the answer presented itself. The connector pin outs are printed on the alternator.

External alternator wiring done. After speaking to the guys at Torrance TAF I think I will wait on installing the capacitor for the external alternator. It seems like they don’t install one and don’t have any issues. It’s easy to install later since I can just tap off one of the terminals on the fuse holder.

I ran some 2 conductor shielded cable out to the Cylinder 2 and Airbox temperature sensors. I originally ran a single conductor wire, but it seems like the practice is to ground the wire at the engine side. There are grounding points near the cylinder temp sensors on both sides, but it looks like the oil temp sensor ground is a little far from that sensor. I couldn’t finish the wiring for these because I want to try to us the terminal covers I bought for the 250 Faston connectors, but I don’t have the correct Faston connectors for this size wire (22 gauge). I order some and will post after I have those wired up. Typically you just use the PIDG Faston connector and leave the metal of the connector exposed, but I was hoping to make it a little nicer. Another idea would be to find small terminal boots that would cover the terminal and the top of the sensor.

Connected up the internal regulator and capacitor.

I made up a simple bracket to hold the turbo servo cable. It will attach to one of the fuel line fittings with 9/16″ nut.

Turbo servo is installed on the firewall. There’s plenty of room between the servo pulley and the sound proofing on the firewall. I think I ended up is about a 1 1/2″ spacer there and a bit longer AN4 bolts then originally used. I need to paint the bracket so I’ll finish installing tomorrow.


Turbo Servo Mounting

Time: 2hrs

I roughed in the mounting of the turbo servo. TAF typically puts it on the engine side of the firewall lower down on the pilot side. The Rotax manual says not to install it on the engine side because the case isn’t fire rated so if you were to have an engine fire you’d probably lose the turbo pretty quick. Personally I don’t think it’s a big deal because if you have an engine fire you probably will shut down the engine so turbo or no turbo isn’t going to make much of a difference. In any case after speaking to Jean at Torrance TAF he persuaded me to mount it on the cabin side of the firewall. Most of the time today was really thinking about where it should go and how the cable should be routed through the firewall. I ended up with a somewhat odd arrangement. Since I used the cable bushings to pass the cabling through the firewall I had issues with where to mount the servo where the cable coming into the servo didn’t interfere with the cabling going through the firewall. I ended up mounting the servo on a slant. So the bolts are level, but the servo itself is slanted. There’s no reason why the servo needs to be mounted level and putting the bolts in level (rather than the servo) was actually much easier.

One thing to note is you do need to disconnect the cable from the servo to pass it through the firewall. The tension on the waste gate is set at the factory, but I just marked the cable so I can put it back at the correct tension setting.

I’ve also been working on the alternator and solenoid wiring. Which I will post in a few days when it’s done. The big time sucker here has been waiting for parts and then realizing you need more or different parts. SO I end up working for 10 minutes and then having to stop. The combination of ring terminal size and wire size is driving me crazy. The PIDG connectors have 3 different sizes and am mainly using the red (22-16AWG) and Yellow (10-12AWG) size terminals, but then I must have every different size of wire lug on the planet… 5mm (which is also #10 BTW) for the starter solenoid, 5/16″ for the master solenoid, 6mm (which also 1/4″ works) for the grounding of the ALT2 regulator, etc… so there are many different connectors you need and you usually don’t have the one you need.

The Turbo Servo mounted slanted, not bolted in yet though. I found that mounting it slanted allows the cable entering the servo to miss the the cables passing through the firewall (blue fittings). It also creates a nice gentle bend around for the cable. I need to wait for some spacers to arrive before I can mount it. I was also thinking of maybe using M6 screws with rivets instead of the AN4 bolts which are kind of a pain to tighten if you’re a “one man” show.

After some time working out different pros and cons of where to run the cable through the firewall I decided to run it through low on the firewall. This is a bit cleaner on the engine side and also eliminates an extra bend if I were to run it up high and then through the firewall. The cable also isn’t that long so some thought needs to go into it.

The cable comes out between the rudder pedals. I’ll install a bracket with and adel clamp and that will pull it closer to the firewall and keep it out of the way of the pedals. I’ve been using the CableSAFE passthroughs (purchased from Aircraft Spruce) to run the cabling through the firewall. I need the kind that comes in 2 halts because the servo cable already has an end on it and it won’t pass through the normal closed type CableSAFE fitting… so now I wait for parts.