Back in 1990, I worked in the Plant Wide Audit group for the Inventory Management Organization at the Ridley Township, Pa., site. The job was to find lost or damaged aircraft parts for the CH-47 Chinook helicopter.
An urgent request came in from the U.S. Army customer that a forward rotor transmission shaft was delivered to the site that had not completed its machining processes and should have been scrapped-out at the vendor. Due to this urgency, the customer was going to issue a grounding of the H-47 fleet until the part could be found.
Not only was the part delivered, but it was installed on one of the Chinooks -- and that aircraft was now in the field. Problem was, no one could identify where the part was or what aircraft the bad part was on. I was assigned the task to find the part, or the aircraft the part was on.
After a two-day investigation reviewing the final flight-test documentation, I found that the serial number for this part had been transposed on the final inspection records and not correctly documented. With this finding, the aircraft was located, thereby averting a grounding of the fleet.