Watching a documentary of the Air France 447 crash, I noticed that even after the “black boxes” (the voice recorder and data recorder) were retrieved from a depth of many thousands of feet underwater, they were still kept immersed in a big tub of water (presumably seawater) all the way for transportation to the investigators.
Why weren’t they immediately taken out of water and put in a nice, dry place as soon as possible? I understand that if the black boxes have withstood the force of water for many months at the bottom of the ocean, then a few more days of immersion in seawater probably won’t do any harm, but wouldn’t people want to minimize the likelihood of water getting into the sensitive electronics as much as possible, which would mean keeping the black boxes in a dry place rather than keeping them immersed in a big tub of water?
I have read that they are transported in fresh water (to help flush the salt) until they are ready to be examined at whatever lab they are taken to. They are then treated with dry heated air to dry them out.
If they are not kept in water until ready to be examined, corrosion will set in. Evidently keeping them submerged in water will minimize this.
Air (well, oxygen) is highly corrosive, particularly in combination with moisture. Keeping already soaked parts submerged keeps exposure to oxygen low until you have the best possible circumstances for removing all moisture.
Ah, interesting, thanks!
Post-crash, the “sensitive electronics” may well be literally toasted. Read up on the pre-installation testing of aircraft black boxes sometime, it’s quite brutal. Once the data is recorded it doesn’t matter if the sensors are destroyed, it’s the memory that’s crucial.
The idea is to keep the data recorders in a stable state until they are in a situation where they can be properly and methodically dealt with. The memory storage is quite protected, but you don’t want to open that inner sanctum until the exterior has been properly cleaned/dried.
Same thing is recommended for hard drives or other electronics (cell phones, digital cameras) that have been contaminated (dropped in a toilet, doused with soda pop, etc) – put them in a container of clean water and keep them there until you get them to an expert who knows how to deal with it.