What you are after is not earthing but bonding, you would find it very difficult to earth an aircraft flying at 30,000 ft or any distance above the ground for that matter.
But they do have a considerable amount of bonding to make sure there is an electrical path between components, in all but a severe lightening strike these bonding points just make sure there is an electrical path to discharge a 'friction induced' high voltage, low current across a join point to avoid the spark discharge such as that obtained by combing you hair, remember that stuff, or stroking the wifes new fur coat in the department store. As bob says that will not stop the potential build up along a plastic pipe which is an insulator in its own right and has a high resistance to current flow along its length, bonding just makes sure that it can leak across to the next piece of equipment without jumping a gap and producing a spark.
The final earth point of the bonding system only has the object of preventing you from getting a 'static' shock if you are well earthed and touch a 'floating' system, it does not have to carry high current therefore any reasonable connection to an earth bonded machine would be enough.
