An A319's number one tire fuse plug melted about 36 minutes after parking at the gate with a 320 degree indicated brake temperature. The First Officer detected the deflation while conducting his preflight walk around.

Narrative

Our aircraft set brakes at the gate. We arrived at aircraft at twelve minutes later and brake temps were 1-400; 2-420; 3-280; 4-280 with the brakes set and mains not chocked. We had the mains chocked and released parking brake ten minutes later. As my First Officer was walking around left mains at twenty one minutes after we arrived at the airport he heard a pop and hissing sound. The number 1 tire fuse plug blew and he immediately advised maintenance. The 1 brake temperature at that time was 320 and number 2-340. The tire was changed and we left on time. One of the mechanics said he had never seen this scenario. If my First Officer had not been at the right place at the right time we could have taxied out and possibly taken off with this condition - we got lucky! I am personally aware of several other tire issues in the last few months and I would like to know at what temperatures the pilots should be concerned and more pro active about hot brakes? What temperature range does fuse plus operate in? Is the brake cooling chart adequate in this scenario? Is additional info required for the pilots to operate in a broader safety range? I see this as a very serious safety issue that requires immediate attention.