Oil Cooler Cross Brace

I didn’t have much time in the shop last night, but I did pick up some aluminum from the Aircraft Isle at Home Depot to make a cross brace on the oil cooler.  This will help reduce impact of vibration and hopefully eliminate any cracking of the baffles over time.  Again I am not worried about the extra weight with this type of reinforcement since I have the composite prop which has saved several pounds by itself.  With this aside from priming and painting, also some changing out bolts/washers for more appropriate support I am pretty much wrapped up with the oil cooler.   Very clean install and I am glad that I can pretty much call this done.

Oil Cooler !

I have been struggling for a long time with what to do about the oil cooler.  For the IO-375 you need a bigger cooler than what Vans provides, but how big and how to mount it?  Vans offers a 7 tube cooler, Aerosport says you can go as large as a 13 tube cooler for this engine..  But there is no way that big a cooler can fit where I need it to.   So in the end I went with a 9 tube cooler mounted per the plans on the firewall.  It’s bigger than the 7 but still small enough to mount per plans.  Others have gotten pretty creative about mounting bigger coolers in the engine mount, or along the firewall, but in my case I wanted to go with the simple baffles installation.  Simple.. Even though, it took all weekend to complete.  :-)

 

Since a 9 tube is larger than plans, there will be more oil weight in the cooler so vibration is a greater concern as it will be mounted out near the cylinder head.   I reinforced the mount pretty significantly as you can see so am not worried about baffles cracking etc.  I am not worried about adding extra weight with the reinforcement since I saved so much weight by going with the composite prop.  I still plan to mount an angle across the front of the cooler for extra torsional strength, but for the most part, this will be my final install of the cooler.   Rather than saying how I did it I will just post tons of photos.  Looks good and I am glad it is done !

Engine Sensors

It was a fun night working on the plane. I had an hour or so and wanted to work on something other than the cowling again, so I worked through the initial install of the engine sensors. Each of the 4 cylinders gets a cylinder head temp (CHT) sensor as well as an exhaust gas temp (EGT) sensor. I put some anti-seize on the collar of the CHT since it was going into the head of the cylinder and then just screwed them in. On the EGT, I drilled a 1/8 inch hole 2 inches below the exhaust collar on each cylinder. Its key to get them all in the same spot and 2 inches was the lowest I could go on #1 cylinder. Also, in order to avoid conflict with inserting spark plugs etc, I drilled these at a 90 degree angle to centerline. There is no conflict with the cowling.

Also I slipped the oil and fuel pressure sensors into the appropriate spot on the firewall.

I couldn’t figure out what was wrong with the oil temp gauge, which should have been the easiest of them all.   It seemed to small and would slip right into the center of the port without even touching the sides..  Turns out Dynon shipped some 7/16 inch diameter probes, vs the required 5/8 inch diameter.   They will be replacing it with the correct size.

Misc Firewall Forward

This weekend was another weekend of only limited progress on the plane.  I worked through odds and ends here and there making only minimal progress.  A couple of orders placed to Vans and Aircraft spruce will allow me to move forward at a faster pace towards the end of this week.  I did run the starter #2 AWG wire and think I got a pretty effective run.  Using Adel clamps to secure it to the engine case and mount as it runs from the starter back to the starter contactor.   I also wired up the Tachometer opening cover I picked up from Andair.  Expensive thing for just a cap, but it was the only one around that allowed for safety wire..  Also, not pictured I torqued the starter which had been previously removed to fit the engine induction system and worked on the heat box which previously had been too far forward and was too close to the cowl.   Moving it back helps create the clearance necessary.

Also, I built a mount for the Dynon GPS antenna and plan to have it sitting on the top of the engine mount.  Others have done this with no heat impact and the fiberglass cowling doesn’t block the GPS signal in anyway.

No More Clecos on the Cowl !

I have been pretty busy epoxying and riveting the cowl over the last couple days and today before running into work it had cured enough to set it on the plane.   Looks really good and I am excited about it for sure, but I did learn one important point.    Don’t let epoxy ooze out between the hinge eyelets.   I thought it wouldn’t be a problem, but the other hinge join interferes just enough to make it very difficult to slide the connecting rod in place.   I have a small dremel bit that I will use to clear out the excess, so I will be fine, but would have rather avoided the extra work.

I also was able to install the nutplates on the center cowl join.  I used two for now on each side and may add 3 later, but there is a conflict with the flywheel that I want to avoid.  Others have stuck with two and have had no issues.  I didn't use epoxy here in case they needed to be replaced in the future.  

Misc Cowl

It’s been a while since my last update.  Things have been busy and I was out of town for a few days.  But in my spare time I have mostly been working on cowling related items.   I got the oil door riveting started.  Also, started prepping the hinges for the cowling.   After drilling the hinges into the cowling, it needs to be countersunk then the hinges need larger holes between each rivet hole, which is designed to grab the epoxy and flux mixture that gets put down below the hinges before final riveting.  The hinges would hold with just the rivets, but the epoxy/flux helps with the vibrations and together with the rivets creates a very long term solution for the cowl.

I also added lay ups over the foam on the inlet fairings.  After an initial filler job and sanding, I now have the approx. 3/8 to ½ inch gap all around the center baffle section.  This needs more filler and sanding, then more filler and sanding, followed by the same, then I will finish the interior with a thinned coat of epoxy squeegeed in place topped by some white primer suited for oils and solvents and such.   Or I may buy some fire barrier designed for this application, but I understand that is heavy, so we’ll see what finally goes in place on the interior of the cowl.