Originally Posted by
Iride01
I've bled a lot of brakes on motor vehicles and even aircraft. However only when it was necessary to open up the brake cylinders and allowing air to get into the system. Same for the airplanes I worked on and helped do annual inspections and other routine maintenance on. None had a requirement for regular changes of the fluid of any corporate jet, private aircraft or any motor vehicle that I worked on. Air in the lines shouldn't be there if there are no leaks and it was properly bled before.
And if there are no leaks, how will moisture get in?
Can't speak for aircraft brake systems, but every auto brake system I've ever owned had a brake fluid reservoir with a cap to allow for the owner to add brake fluid. These are never 100% airtight. Neither are cylinder or caliper seals.
I'm also reasonably certain that every major auto manufacturer has had a recommended brake fluid change interval of 2 or 3 years since the 1980s. Reason? Brake fluid absorbs water from the air. And that is not a good thing for either brake system longevity or brake performance..
Since needing to have a brake system redone on a 5 y/o vehicle some decades ago, I have indeed had brake fluid changed regularly - every 2 or 3 years. And I've not had to have much if any brake work other than new pads since.