A SAV is a Staff Assistance Visit.
Generally speaking the staff from the superior headquarters (in the CF H Svcs Gp's case either 1 HSG, 4 HSG, 1 Dental Unit, or Directorate(s) within the CF H Svcs Gp HQ) come down to provide information on the going on's at the HQ, update the line units on projects, seek information for their projects and reporting, introduce themselves and most importantly provide face-to-face assistance on non-technical problems the line unit is having.
It is a good chance for Staff Officers to get out of the HQ and get some face time with the people they are supposed to be supporting. A chance also for the line unit to make "informal linkages" in so that you know who is in the know at the higher HQ and who you can call to see "what is up?" while waiting for information to come down official channels from the big black hole.
If the problems the line unit is having, often it is termed a technical assistance visit or TAV. For instance, when an X-ray tech cannot get some x-ray thing working properly they may send in a senior x-ray tech to help sort the problem out. This is a TAV.
There are also Staff Inspection Visits (SIV) and Technical Inspection Visits (TIV). These are used when the HQ wants to ensure that the line unit is in conformity with policy, procedures, and equipment matters. They tend to be a lot less enjoyable for the line unit, especially when conducted unannounced / with minimal announcement.
Let me know if that does not make sense.
Cheers,
MC