Finished fabricating the ELT housing platform by updrilling all the rivet holes to A4 (1/8"), disassembling the pieces to debur, file, sand, then paint the mating surfaces. Once dry, I installed 4 #8 nut plates into the top of the platform and reassembled it. I made short work of riveting everything together then I installed the mounting bracket into place. Finaly, I strapped in the ELT just to make sure it fit ok. Tomorrow, it's back into the belly of the plane to install all of this.
Completed ELT housing platform with nut plates installed for mounting bracket screws.
ELT platform with mounting bracket and locking straps installed.