Engine Work Complete

TIme: 6.75 hrs

Over the past week or so I worked on getting the engine finished up. I’m sure I’ll still have a few things to do on the engine, but I wanted to get as much finalized as possible so I can move onto other things. There’s just too many open projects going on at once and I’m starting to lose track of where things are at when I come back to them.

I took a bunch of photos so I’ll just describe what I did after each of the photos. I know I still have a few pending things firewall forward but the bulk of the engine work should be finished. Items remaining are:

  • Purchase and install EarthX battery – I don’t want to by this too soon since it will just need to be charged periodically and should be pretty easy to wire up.
  • Adjust alternator belt, torque bolts and safety wire – I need to get the prop installed before doing this
  • Finalize the throttle and choke cables – I need to wait until the panel is installed or I at least have a good idea where the choke knob will be mounted so that I can cut the cable to the correct length.

I installed the External and Internal Alternator fuses in the engine compartment. I know some people have used circuit breakers in the cockpit, but I didn’t like the idea of running long high current wires unfused and if the breakers were to blow you’re not really supposed to reset it anyways so I decided I’d just put them closer to the source. I also uses a braided ground strap rather than just a wire. It’s easier to see if it’s broken.

Here’s what I ended up doing for the left side coolant hose. NOTE: I should get a picture of the bracket that’s mounted to the exhaust. In any case the hose is supported by a bracket that mounts on the exhaust and then attaches to that using an M8 bolt through the adel clamp. I used a very flexible silicone hose for the coolant hoses. For this side I had to also fit a 60º bend to this main hose since I wasn’t able to get this main hose to bend that tight into the radiator.

You can also see I wrapped the exhaust which I found a few other people doing and one of the guys at Torrance TAF had said was good to do. And you can also see the EGT sensor which I only ran to the rear mounting holes on each side. I had read that doing all four is not really necessary.

I ended up replacing all the nylon locking nuts for the engine mount with all metal locking nuts. I also did this for all the various clamps, etc. You’re not supposed to use nylon locking nuts firewall forward, though I see a few on the Rotax engine (from the manufacturer) so I would expect they should hold up OK.

Just a overview photo of the wiring routing and fuel lines in/out of the fuel regulator.

I’m using silicone and stainless steel teflon hoses so that I have minimal hose replacement when I have to do the 5 year rubber swap outs. The only rubber hoses left are what’s on the engine and in the fuel pump assembly. When that time comes I’ll try to replace those with appropriate non rubber hoses. The one silicone oil hose (connected to the oil tank) is special and is fluorosilicone lined to hold up the the oil.

I used adel clamps to hold the oil and fuel drain lines… kind of overkill I guess. I also combined the left and right side fuel drains so I only have one hose fuel drain exiting the cowling. I still need to cut the drain line hoses a bit shorter.

Another overview photo. I made a few short clamp extensions from stainless steel sheet. One was used to connect the 2 adel clamps for the main oil line that runs from the oil tank to the thermostat. The other connects the 2 adel clamps that are used to hold the fuel line from the fuel flow sensor to the right carb. I also made a bracket to hold the fuel flow sensor.

I ended up running both the oil lines between the thermostat and the oil cooler on the right side. There was just no good place to secure the hose if I ran it on the left side and it comes very close to hitting the cowling and alternator.

Just a shot of the rear portion of the engine. You can see the red wire that runs to the starter and quite a few adel clamps that were used.

UPDATE (09/05/2019): Adding below photos that I forgot to take and some more info.

I was able to get the extension loom from Air Master for about $100 with DHL shipping. This is an extension cable so there are connectors on both ends and Martin (at Air Master) said to leave about 20″ from where the slip ring will be installed which on the Rotax 914 in the center of the engine on the top where I believe the vacuum pump is mounted if you had that option. Having this cable allowed me to close up the firewall for where all the cabling goes through. It’s made from 2 pieces of 1/16″ stainless steel that screw onto the firewall there are grommets also in there for the cables to pass through. Then I put the stainless steel grommet guards on.

Here’s what I ended up doing for the left side cooling hose. I purchased a stainless steel exhaust hanger (9″ JEGS 309002) from Amazon and bent it at around the first hole. I also purchased a stainless steel 1.5″ U clamp to clamp the bracket to the exhaust. It seem pretty sturdy so should work well. This keeps the cool hose away from the exhaust manifold and secures it from moving around.

I didn’t have a photo of how I did the fuel flow sensor. I made a bracket to mount it to the same mounting holes as one of the engine sensors. The hose coming off the regulator is split and feeds the flow sensor and will also the pressure sensor which is mounted on a plate on the engine mount. My only worry is that the 90º bend it pretty close to the inlet of the sensor and the Red Cube manual said not to do that. I spoke to a few people about it and they think that because I’m only pulling 5 gallons an hour it shouldn’t matter, it might matter with a higher volume of fuel since the bend can create some turbulence in the flow and mess up the sensor readings. If I get inaccurate readings I have an alternate idea of how to run the hose so will have to see.

On the ride side of the engine it’s a tight fit for the exhaust manifold, cooling hose and oil line. I probably should add something to hold the oil hose to the cooling hose to keep it from touching the exhaust.My other worry is that the box that goes around the air filter will hit the cooling hose so I’ll have to move it… will have to wait to see when I get the air box.

TAF Service Bulletin #0014

TAF sent a Service Bulletin on 8/18/2019 on replacing rivets in the wing spar and fuselage with stainless steel rivets. I guess the aluminum ones will start to give too much and cause cracking in the paint. Fortunately I haven’t riveted the skins onto the wings yet so at least that part I don’t have to redo, but I will need to drill out and replace all the rivets along the bottom to the main spar in the fuselage.



Time: 8 hrs

Over the past week or so I’ve been working on and off on the flaps. Theres a lot of prep work, plus priming before assembly so it take a lot of time. Plus I wanted to let the primer dry for a few days before putting things together. In any event the flaps are mostly done. I’m still missing rib #1 so I’ll have to rivet that in when I get it. I also left most of the leading edge unriveted so that I can get it to match the wash in the wing when the wings are completed.

The flaps went together very quickly, no big issues in alignment or fitment. I did end up using 12mm long 4.8mm rivets in rib #102 to fit the bracket to the side of the rib since the 15mm rivets seemed a bit long. The manual only says to use 4.8mm rivets and doesn’t say a length. I assumed they wanted 15mm all around since they provide you with so many. In most cases you need the extra length because there are a few pieces to get through.

I’ve also been working on finishing up the engine. I’ve been waiting on some parts so that I can mount up some of the hose, etc. I’m also seeing if I can get the sensor cable from AirMaster for the propeller so that I can finish up all the engine wiring through the firewall. They said they’d sell it to me and I’m now just waiting on a reply to see how to pay them. So hopefully I’ll have that finished up in a week or so and I’ll take a bunch of photos.

The flaps mostly riveted. The leading edge is left unriveted so that I can match the wash of the wings when they’re done. Everything went together pretty quick.

Rear Spar

Time: 4 hrs

Finally got to do some riveting on the wings. I finished up most of the rivets on the rear spar, but still need to rivet the larger 4.8 rivets. I want to wait on riveting these ribs because I need to make sure the holes are large enough for the wiring, just in case I have to widen the holes. Everything went fairly well, I needed to up a few hole sizes and had a few alignment issues, but over all not too bad. The manual shows to rivet the skin support channel onto the rear spar first, but it seemed like it would be difficult to rivet the ends of the ribs so I decided to do the trailing edge of the ribs first and then fit and rivet the support channel. That seemed to work well.

I also fit the AN3 bolts on ribs 12 and 13 and will tighten them later. The manual says to fit them with AN3 bolts but not the size so I just matched the existing bolts which appear to be AN3-14A with a thin washer on the head side and a thick on the nut side.

Rear spar mostly done with the trailing edge of the ribs and skin support channel riveted. All the rivets are done from this side.

This is a photo of ribs 12 and 13. The top and bottom holes of these ribs are fitted with AN3 bolts to continue the row of bolts used to hold the spar together.


Time: 4.5 hours

Today I assembled the ailerons. It all went together very well except for some issues around rib #3. The issue was I wasn’t able to get the leading edge to close up. It almost seemed like the ribs was too large. I disassembled most of the aileron, took out the metal reinforcing tube and then it seemed to close so I thought the issue maybe was the circular cut out in the rib wasn’t large enough for the tube. I compared the cut out with one of the other ribs and it seemed ok. What seemed to work was I relaxed the bend in the bottom half of the skin along the leading edge by just bending it with my hand. The holes then lined up much closer and I was able to get clecos in them. Once that was figured out I riveted the trailing edge and just left clecos in on the leading edge so that I can warp it to follow the shape of the wing when it’s finished.

Even with being very careful in the prepping of the ribs and putting bends on the tabs of the ribs I still got a small bump in the skin where one of the tabs was a little high. This happened on the rib that is doubled up so it’s a bit more rigid then the other ribs. Oh well, it’s not that bad so will just have to live with it.

I also starting prepping the flap ribs so I can get that going next.

Ailerons are done. I left checks in the leading edges so I can get the correct twist on them to match the wing trailing edge.



Time: 5hrs

Nothing exciting today, just primed some of the rear spar parts (trailing edge ribs and reinforcing channel), aileron skins, and a few rib parts that I was missing that came into TAF a few days ago. I also got most of the parts for the flaps so I prepped those to be primed. I should be able to start riveting the wings together this weekend.

Wings Progress

Time: 6 hrs

Finally getting back to working on the plane after a long vacation. I made some good progress on the wings. I set up the main and rear spare in the jigs on the rear porch. The porch is surprisingly level. I just got things close so I’ll have to go back and get the jigs completely leveled out, but it should work out fine. The tables I have aren’t really large enough to build both wings. I should be able to get both wings built up to putting on the leading edge skin, then I’ll have to finish up one and then process with the final wing. I test fit the ribs that I had primed and assembly a few weeks ago. Everything seems to fit well. I’m also going to prime the main spare where the ribs overlap. I wasn’t going to prime the main spare at all since it’s anodized aluminum, but the brackets seem to be regular aluminum so I’ll just prime them to make sure.

I also prepped most of the remaining ribs. I’ll see if I can clean and prime them during next week some time so I can hopefully install them over next weekend.

Spares in the jigs for the left and right wings and a few of the main ribs test fit. Not a whole lot of room to work here, but not too bad.