Hi Susan,
I am a little confused how you could have an "outside internal audit". I can see a gap audit from an outside consultant but the internal audit is supposed to be done internally by staff employed by the company.
For example at my company the managers meet monthly and then each month a different group of 2 or 3 managers does the self audit interior and exterior of the facility which includes going through the glass and brittle plastic, GMPs and we document all of our findings and corrective actions.
We have a schedule we follow to make sure on an annual basis we cover prerequisite programs, maintenance, allergens, food defense, food safety, mock recalls, HACCP, water, air and ice testing, etc.
At least one person from the company must be trained and competent in in internal audit procedures ref. 2.5.5.2. Once completed that person can train others in the company on internal auditing.
There is a caveat where practical staff conducting internal audits shall be independent of the function being audited. If you are a small company this can be difficult.
The most important part is all records of internal audits and inspections and any corrections and corrective action taken as a result of internal audits shall be maintained. If it hasn't been documented it hasn't been done.
I hope this helps. Please let me know if you have any questions.
Thanks!