As a graduate test pilot member of a large helicopter operating company's design and flight test department, my authority to conduct airworthiness flight tests is legislated in the Company Maintenance Exposition, as is the case for training captains etc, as mentioned by 212man (or are you EC155man now?).
Operating in an independent capacity, I have a personal approval from the CAA: which to obtain normally requires a form filled in, a briefing and usually an observed AFTS with a member of the CAA Flight (test) Department. That's how it is in UK; same for fixed-wing I believe.
Last edited by idle stop; 16th November 2004 at 17:04.