The FAA proposes to adopt a new airworthiness directive AD for certain ATRGIE Avions de Transport Rgional Model ATR42 and ATR72 airplanes. This proposed AD was prompted by a report that for airplanes converted from passenger to cargo configuration using certain supplemental type certificates no height limitation for the cargo when loaded in the cargo compartment is defined and that as a consequence cargo might be loaded up to the ceiling of the cargo compartment. This proposed AD would require modification of the cargo compartment and implementation of updated cargo loading procedures. The FAA is proposing this AD to address the unsafe condition on these products.