Dependant on the NAA/State of Registration - the cables MAY be extended by 10% if necessary.
But that is not a hard and fast rule - I don't know if these cables are subject to AD actions.
Malcolm,
Forgive my "Black-and-White" attitude, I'm from the big jet world.
AD's are legally binding and all the other stuff is at least recommended and, at most, highly recommended by the OEM/manfacturer. (try telling Airbus that!) Only NAAs can make maintenance actions, Lives and Inspections "mandatory".
However, if, during an post accident investigation, a fault is found to be caused by a component that has overrun its recomended life or has not had some recommended maintenance, then I'm pretty sure the insurance is unlikely to pay up?
That doesn't mean its all mandatory but, in good-ole' hindsight, one might be considered quite foolish for not doing the recommended jobs.
Think of all those Aussie farm accidents...