well aware of the certification requirements OEI and some types (B737 for example) have it in the flight manual but other types don't (not seen it on a bombardier aircraft for instance) and I have never seen it as a certification requirement. I'm asking where the certification requirements are that mandate a minimum flap retraction altitude all engines operating - never seen it, never heard of it. Flap retraction is predicated on speed not height with a minimum height (not altitude) in the event of an engine failure.