A 767-300 passenger aircraft undergoes major modifications during passenger-to-freighter (PTF) conversion. First, the passenger interiors, equipment, and furnishings are removed; and then a main-deck side cargo door is installed and the main-deck floor structures are replaced or strengthened. Next, a 9-G rigid cargo barrier and a new cargo handling system are installed. Airlines may also consider adding features such as carbon brakes, avionics and flight-deck upgrades, live animal and perishable food carriage, weight increases and integration of technical manuals during the PTF conversion.