The FAA has posted a new rule requiring owners of small unmanned aircraft systems (UAS/drones) to display an FAA-issued registration number on an outside surface of their aircraft. Previously, drone registration numbers could be placed in an interior compartment as long as that compartment was accessible without using tools. The new rule will not change the process for registering drones and, beyond requiring that the number can "be seen upon visual inspection of the aircraft's exterior," doesn't specify an external location for the registration number.
This is a companion discussion topic for the original entry at https://www.avweb.com/recent-updates/business-military/faa-requiring-visible-drone-id-numbers