The AS9100 Rev D standard, as with the ISO 9001:2015 standard, does not state what is required for auditor competence for internal audits. So, as with all processes it is up to the company to define what the competences are for the internal auditors. If you define your competency as “having taken an AS9100 Rev D Internal Audit Training Course” then having taken an ISO 9001:2015 internal audit training course will not be sufficient.
However, if you define your competencies as 1) understanding AS9100 Rev D, 2) Understanding process auditing, and 3) understanding the internal processes to be audited then you need to find a way to address each of these competencies. As process auditing is the same in ISO 9001:2015 and AS9100 Rev D then having the competence to audit is covered and all you need to fulfill is the competence to understand the AS9100 Rev D standard.
For an understan ding of what is included in AS9100 Rev D see this whitepaper: https://info.advisera.com/9100academy/free-download/clause-by-clause-explanation-of-as9100-rev-d