Brief Description: Fabricate and Install Fuel Line Doubler
The IO-360 fuel injected Lycoming calls for a firewall fuel line doubler riveted to the forward side of the firewall. The doubler holds the AN833-6D elbow. Drawing OP-32 shows the dimensions of the doubler and the location on the firewall. First, I fabricated the doubler from AS3-063 aluminum sheet. I marked and drilled the four rivet hole locations to 3/32" and also marked and drilled a pilot hole for the fuel line elbow. The plate is attached to the firewall with AN426AD rivets. One hole on the doubler matches a firewall doubler rivet location. I drilled out that rivet and clecoed the doubler to the firewall. I match drilled the remaining rivet holes and the pilot hole for the elbow. I clecoed the remaining 3 rivet holes and used my cobalt step drill and Boelube to enlarge the pilot hole to 9/16". I removed the doubler and deburred the holes. I machine countersunk the rivet holes. Next, I scuffed up the doubler , cleaned and primed with gray self etching spray paint. After drying I riveted the doubler to the firewall with AN426AD rivets and firewall sealant, installed the AN833-6D elbow,washer and nut and torqued to 160 in-lbs.
