I thought I had a good wooden prototype bellcrank for the oil cooler door control last weekend. But when I took a look at where I would have to bring the Bowden cable through the firewall, I noticed that there was already a bundle of engine wiring coming through there. I couldn't move that bundle anywhere else without cutting a number of EGT probe wires, and the linkage geometry didn't allow me to bring the Bowden cable through anywhere else.

So, after much head scratching, I changed the linkage design, so that the Bowden cable was no longer anchored at the firewall. This gave me some flexibility in where it came through the firewall. But, the new design had some other issues, so I moved onto version 3. That version was better, but it still didn't solve all the problems. Version 4 looked good, so yesterday I made an aluminum version. Today I drilled the holes in the pivot support, so I could clamp it to the engine mount tubes. I messed up one of the hole locations slightly, which moved the pivot point, which meant I had to shorten one of the bellcrank arms. But it worked.

 


Tonight I primed the parts. I have to rivet them together, rivet the Bowden cable attachment bracket to the landing gear box in the cockpit area, put a fire guard over the grommet, and secure the Bowden cable. I also need to fabricate a stop to limit the downward travel of the oil cooler door, so it can not hit the exhaust pipe.

I posted some pictures of the oil cooler door many months ago.