Data can be recovered from many drives even if all plastic components are melted, and otherwise the hard drive looks like a blackened mess.

The architecture of a hard drive has two main components - the electronic board and the head assembly. The head assembly houses the rotating platters which contain the data along with read/write heads that do just that -- read and write data to the rotating platters.

There is a small hole in the head assembly (pin size) whose purpose is to compensate for atmospheric changes (if the head assembly was completely sealed the head assembly would need to be much stronger to accommodate atmospheric changes). The amount of air that enters this pin hole is negligible over time.

Of significant risk is the water used by fire fighters entering this small hole. In this case, speed is of the essence. If the platters are accessed before the water dries, then there is still a chance of recovering the critical data on the drive. If the water does dry, it leaves behind minerals, dirt and other foreign materials throughout the drive, most importantly, the head assemble and platter(s). The chances of recovery at this point are less.

Another risk to the head assembly is that the heat was so intense that the platters experienced melting. In this case there is no hope of recovering data.

 Our experience is, however, that even blackened drives have undamaged head assemblies. The challenge in recovering data is to rebuild the electronics to access the data.