Mercedes E class rear brake pipes

I don't see many of these but twice now I've had a brake pipe burst on the rollers. At the rear you can see about 2 inches of the pipe each side but above the rear undertray and behind the wheel arch liners they can be absolutely rotten! Todays one for instance the green coating was still intact on the parts you could see and not even bubbling but now with trays off and arch liners out it's horrific! Both about 11 or 12 years old. Maybe it's just the Devon country roads (a lot of mud and crap gets above and behind the covers) but be very careful with these!
Of course if we still had an advisory for parts not visible that would be nice too but I'm thinking of manually advising these.