Thanks Carl.
I wonder how much dehumidifying prevents the need to change those black boxes which cost a small fortune every time they are removed. If it saves just a few then it is a good investment. Nice to see the airforce protecting taxpayers investment in avionics. Seems they are the only aircraft fleet that is applying this idea to improve in use reliability as opposed to storage.
The theory is that if a nice warm circuit board is switched off at ground level (High relative humidity) and then cools, condensation forms and this leads to corrosion of conductors or short circuits. If, as soon as possible after shutdown, dry air is pumped in this can be avoided. First few moments after shutdown are critical when hot, then maintain the dry atmosphere until just before next start.
I suspect that the airforce Nimrods have especial need operating over/near the oggin.
Overall, I suspect limited current application by airlines but there may be reliability potential, which is exactly what I hope to study for a project for a course I am taking. I just need to find an airline with experience or willing to experiment!!
I am still keen to hear if any airline dehumidifies avionics for reliability purposes- possibly long haul jets that may spend longer on the deck than short haul??