1. Installed two baggage tiedown rings on floor of aft baggage compartment. Drilled attachment holes for two more on the upper hat shelf. 2. Removed transponder antenna from belly of airplane. Trimmed Dynamat sound dampener to fit antenna backing plate. Cleaned inside and outside skin area, removing all Dynamat residue. Marked and drilled backing plate for 20 rivets. Drilled all 20 holes. Clecoed backing plate to inside of skin. Match-drilled holes through fuselage skin. Removed backing plate and countersunk all holes. (Tomorrow, I will get some help and dimple the 20 holes in the fuselage skin, and rivet the plate inside.) 3. Removed ELT buzzer to rework its wiring harness a bit.