There are generally agreements between the various countries’ aviation certification authorities so that a system or aircraft is certified in the country of its

There are generally agreements between the various countries’ aviation certification authorities so that a system or aircraft is certified in the country of its design/manufacture and it is accepted in other countries. The harmonization of the rules between countries is always fun. For example, I worked on a program where we certified the glass cockpit upgrade for the US Navy trainer, T-6A to T-6B with Transport Canada, the aircraft with the new avionics was certified by the FAA, and the whole system was then accepted by the US Navy. Satisfying all 3 stakeholders at the same time often proved difficult.