Does a conversion for wheel to floats require an STC or Form 337? When you add floats to a tricycle gear (e.g. Beaver) do you need an STC to install the TSO'd floats? Or can this installation be approved with a Form 337 for a single aircraft?
This sounds like a major mod, but I will have to see the design data to really able to come to a conclusion. If its a major mod, it has to be done via an STC.