AerocatS2A, re #4
My belief was that previous advice on grooves related to damp vice wet, but I am unable to locate any earlier documentation relating to this or anything different in the old JAR-OPS.
A conclusion might be that this is another gap between aircraft certification and operational regulation, where the operator is left without advice other than to choose a safe option.
Re 146; I would be surprised if the quoted wording was in the AFM. In the Ops Manual may be, but then the data would be advisory.
I recall that one operator (possibly UK) operated on a very short grooved runway in Europe to the effectively dry requirements of JAR-OPS in wet conditions. I suspect that this was an operational approval and thus did not involve the manufacturer.
Be that I am surprised by the AFM revelation, then this would be an accepted position from both the manufacturer and the certificating authority; but even then the operator has to decide if the damp conditions reported are as the manufacturer intended/tested. The AFM damp definition would probably match the UK AIC (1.1.1), but then what about the rest of the world.
Thus in failing to answer the question and possibly adding to the regulatory confusion, we do appear to agree that damp = wet.