Air carrier aircraft Inspector reported that a rudder PCU they had worked on previously was found installed with a missing bushing.
Synopsis
Air carrier aircraft Inspector reported that a rudder PCU they had worked on previously was found installed with a missing bushing.
Narrative
Day 0; I was approached by my base manager about a maintenance discrepancy I was involved in two years prior. I was the Required Inspection Item (RII) inspector for an upper Rudder Power Control Unit (PCU) change that was written up for failing the Actuator Integrity Test during a check. Recently A/C experienced Rudder Trim issues that was later discovered to be caused by an upper Rudder PCU attach Fitting fracture. When the PCU Toggle Bolt was removed from the upper Rudder Fitting; it was noted that a Bushing was missing from the attaching hardware. After reviewing the maintenance history of the Rudder; the last time there was documented evidence that the PCU was worked on was the upper Rudder PCU change two years prior. I remember being involved in the replacement of the upper Rudder PCU as the RII inspector and following strict guidelines while performing my RII duties. The mechanic replacing the PCU and I followed the exact Aircraft Maintenance Manual (AMM) instructions and also had a copy of the Aircraft Illustrated Parts Catalogue (AIPC) of the PCU and its attaching hardware present as a reference to assist us in completing the task accordingly. To the best of my recollection from the time of the PCU replacement and now; I believe all installation procedures were followed along with all the necessary effective hardware. Unfortunately due to the time that has passed from the time of the replacement; it's not clear weather or not myself and the mechanic involved were the last ones to work on the PCU.Suggestions:I remember having to change the number and size of the Washers for the Castellated Nut to torque and align property with the Bolt hole. There was repeated actions of removing and installing the Nut and Washers. At the time; I was new in my role as a qualified RII. Since then; I've had time to learn and grow to be more proficient in my role. To take my time and inspect carefully the work being performed.
Second reporter narrative
It was brought to my attention by mechanics on the floor that an aircraft with significant damage to the rudder/Power Control Unit (PCU) attachment points was brought in to be worked on. Several mechanics throughout the night also informed me that it was discovered that the PCU in question; which may have caused the damage; was missing a bushing; and that I had; in fact; installed the PCU at an earlier date; 2 years prior. Although I remember explicitly installing the PCU in question due to a routine PCU operational check failure; I do not recall any issues or hang ups in the removal and install. Due to the nature of the job and the critical location and function of the area being worked on; I have always made it a point to be especially attentive and careful reading the manuals and job cards as well as staying in constant contact and communication with the inspector performing the RII procedures. To my knowledge; the job was completed to the letter and all operations checks were performed and passed successfully.Suggestions:Because it was never officially made clear to me whether or not the damage was due to my alleged negligence; I can only suggest that communication of concerns with any mechanic on any job be brought directly to the attention of the mechanic(s) in question in a clear; concise; and prompt fashion. Doing this can reduce or prevent any false information or presumptions being made. All things considered; I am genuinely glad and reassured to know that; regardless of the alleged cause; the damage to the aircraft was discovered and repaired appropriately and efficiently; insuring the safety of the aircraft as well as the crew and passengers.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.