Read the Naval Aviation Maintenance Program Standard Operating Procedures for FOD control. The FOD program is on Page 142 of the document or 150 of the PDF file. The Tool Control program is on page 151 of the document or 159 of the PDF file.
A vortex initiates due to the presence of a prevailing wind that blows at an angle to the intake face and forms a shear vector that causes the airflow-to-ground-plane interaction to swirl.
