High Humidity and Avionics
Anyone who has been involved with tropical trials of aircraft at places like Darwin, Oz will know that you can pour water from a recently flown black box.
We.RAAF, had lots of trouble with avionics in Mirage and F-111 despite conformal coating of circuit boards.
Water seperators in the ECS help but potted circiuts, conformal coatings and sealed connectors add up to greater reliability.
Aircrew suffer also as the ECS systems are prioritised to look after the avionics before the crew!!