Cut a backing plate from 1/8" Al. Located AN3 nutplates with previously drilled oil filter body using machinist blueing and a scribe. Drilled 2 #30 holes in backing plate for riveting to firewall. Located filter housing on starboard side of the firewall. Drilled 7/16" holes in firewall with step drill. Deburred and bolted filter to firewall. Drilled #30 holes in firewall for recessed rivets. Dimpled firewall mounting holes. Removed oil filter housing and rivited backing plate to firewall with two CCC-44 rivets. Bolted oil filter to firewall with AN3-7A bolts.
