Surprised? I just dropped off the driveshaft at the balance shop. They put the 2 pieces together and balance it full-up on a rig, including mounting the mid bearing. Makes sense! After all, how else would you be able to account for modes associated with looseness or more complicated dynamics stemming from the coupling? I can tell you from first hand experience in the aviation industry dynamics is a counter intuitive and unforgiving business. The runout measurements shown in the FSM under PD reflect tolerances beyond what was delivered from the factory, not a necessary condition for the shaft to be balanced but would likely indicate problems if runout was beyond expectations. At the end of the day the balanced shaft is what's important, not the runout tolerances.
OverZealous (CT) My General posts (click) |