Rotormatic, you miss my point - which to be fair I didn't explain in depth.
FAR-27 and 31 has an applicability paragraph which technically includes gyros. However, the technical content of the standards is purely written around Helicopters. I have heard UK CAA officials say that they won't accept FAR-31 certification of the V-22 for the same reason, this beast is not a helicopter and a dedicated standard is needed.
Incidentally we're no better off in Europe; the JAA is currently hawking JAR-VLR (Very Light Rotorcraft) about the bazaars, yet if you read the draft it says it includes gyros, but in the text permits only a skid undercarriage. There is no gyro theory within the text, it's all entirely written around helos.
The world needs a CofA gyroplane standard to allow projects like the Cartercopter to succeed. (And something for the tilt-rotors too). The only standards is existence (such as BCAR Section T) are for small sports aircraft. FAA and JAA need to get together, probably start with the work done in the 60s to certify the Fairy Rotodyne and work out from there. But FAR-31 is not a standard that can sensibly be used.
G