no pilot or eng. doing a P.D.I. would have a clue as to how many bonding straps were intact or broken . During C Check I can regularly find broken or frayed straps on on flight controls. which could have been in that condition for months. And thats the way they would stay until a job card calls for an inspection that would make an engineer aware of the defect. you can't reference an M.E.L. for things you don't know are broken.