14 CFR § 145.153

A certificated repair station must ensure it has a sufficient number of supervisors to direct the work performed under the repair station certificate and operations specifications. The supervisors must oversee the work performed by any individuals who are unfamiliar with the methods, techniques, practices, aids, equipment, and tools used to perform the maintenance, preventive maintenance, or alterations.

Each supervisor must—

If employed by a repair station located inside the United States, be appropriately certificated as a mechanic or repairman under part 65 of this chapter for the work being supervised.

If employed by a repair station located outside the United States—

Have a minimum of 18 months of practical experience in the work being performed; or

Be trained in or thoroughly familiar with the methods, techniques, practices, aids, equipment, and tools used to perform the maintenance, preventive maintenance, or alterations.

A certificated repair station must ensure its supervisors understand, read, and write English.