ATC Supervisor reported an aircraft entered HIO airspace without a proper clearance. The Supervisor stated this is a continuing problem at this location and some form of communication needs to take place with the personnel at the smaller neighboring airport; 7S3. Per the reporter; air traffic from 7S3 routinely violate the Class D airspace at HIO.

Narrative

Aircraft X was observed violating the HIO Class D Airspace after departing Starks Twin Oaks Airpark (7S3). The aircraft entered the airspace from the south to about 2 miles south of the airfield. From our control location; I noticed the primary radar return on the STARS; then looked out the window and observed the aircraft out the window. there were several other aircraft in his vicinity and I advised the Local Controller of the airspace violation. Local Controller had to make several traffic calls for the aircraft before Aircraft X finally contacted the Tower over TV Highway approximately 2nm south of the field. The pilot requested to transition northbound through the airspace.There needs to be more communication with 7S3 so that they understand the severity of the issues they are causing by having their aircraft and patrons routinely busting the Class D Airspace. There needs to be harsher penalties; and more follow up from FSDO so that this stops. It has been going on for more than a year on a routine basis.Do we need to incorporate an LOA with this airfield and HIO? Maybe.The addition of the charted TIMBERS Transition Route may be contributing factor now as well.