Maintenance Planner and Crew Chief reported the wrong engine was replaced during a scheduled maintenance resulting in overflying an engine that required replacement due to time cycle restricted components having reached their service limit. The aircraft was removed from service to correct the discrepancies.
Synopsis
Maintenance Planner and Crew Chief reported the wrong engine was replaced during a scheduled maintenance resulting in overflying an engine that required replacement due to time cycle restricted components having reached their service limit. The aircraft was removed from service to correct the discrepancies.
Narrative
Aircraft X was scheduled for a Right Engine Change in our Company Maintenance Base in ZZZ. The purpose of this Engine Change was to comply with the following tasks - Objective 1 - R&R STAGE 1 TURBINE DISK; LIFE LIMIT; Objective 3 - R&R STAGE 1 AFT COOLING PLATE; LIFE LIMIT; and Objective 2 - R&R STAGE 2 TURBINE DISK; LIFE LIMIT. Per Company's direction; these tasks must be low in cycle count to be changed. Objective 1 and Objective 2 were at 7 cycles at the start of the flying; Objective 3 was at 4 cycles at the start of the flying day. Maintenance for this Engine Change was scheduled over the course of three days (also referred to as a CML (Continuous Maintenance Line) or Weekend Down). The plane was scheduled to be inducted into Maintenance at XA:45 on the first day; and be released at XB:00 on the third day. This was extended 1 day longer due to needed Maintenance Actions within the Maintenance Hanger. The plane was noted to be completed on Date. Maintenance Personnel sent the corresponding work order to their inspector on duty; the Inspector cleared the completed work order and scanned it into the database for planning review and closure of said work order. I closed the work order and carried on with the duties assigned to me by my manager. The aircraft was released back into operation by Maintenance Control and was dispatched for 6 flights within Company's market. The aircraft would then park in a Company Contract Maintenance base in ZZZ1 for the night with Objective 3; 2 cycles over its limit. The following day; Maintenance Control noticed that Objective 3 was showing -2 on the maintenance due report and questioned Maintenance Planning. Person A sent a copy of the page showing the negative with a message. The Maintenance Planner on Duty then replied 10 minutes later. Person B then sent an email to the Company Power Plant Team as well as the Records Department questioning this negative cycle count. Come to find out; ZZZ Maintenance changed the wrong Engine on the aircraft; and the Engine that flew the 6 cycles was indeed overflown by 2 cycles. This was discovered on Date 1. The plane was grounded and corrective action was taken by ZZZ1 Maintenance. Several things can be corrected here; first and foremost; if the correct engine was changed; we would have closed the work order and expected Aircraft Records to update the tasks that were showing due. This is because instead of scheduling the industrial tasks; we at Company scheduled a pre-made Engine Change Job Card. This does not take compliance for the tasks; but for an Engine Change itself. In this situation; a good change could be for Maintenance Personnel to write a Work Card requesting Maintenance Planning to take compliance for the tasks showing due or the tasks showing due be added to the work order with the Engine Change Job Card. But in this situation; the wrong engine was changed; therefore we would have still been overflown because we would have been taking compliance for the wrong engine. It is normal to let the task fly until Aircraft Records updates the information because we see that the engine change was signed off. This is for NLG; MLG; and Engine Changes. This is a very lax system; and the one fact no one saw coming hit it resulted in an overfly. No one would have imagined that ZZZ Maintenance would change the wrong engine; everyone assumes that the procedure down line would fall into place and everything would be taken care of accordingly. Also; [the computer system] updates Hours and Cycles on our Maintenance Due Reports and [spreadsheet] once a day; that is in the early morning before flying has occurred. Therefore all day those tasks were doing positive until the update the following morning where it showed negative. The engine is well overflown at the point; but the [spreadsheet] is still showing 4; and any Maintenance Due Report at this time would also show 4 in the cycle count section.
Second reporter narrative
On Date; Aircraft X came in for a RH Engine Change. While positioning equipment that night I misread the position on the job card as LEFT. There was a heavy weekend coming up and I was hoping to turn the engine quickly to free up resources for the weekend. In my attempt to get a jump start on the change I did not verify S/N of the Engine to be removed and put the S/N off the job card on the Supplement. The result is that the LEFT Engine was changed instead of the RIGHT. This was my second engine change unassisted as a Crew Chief and I was focused on the actual change procedure. I also was under the impression that a recently repaired LH Engine was the one to be used; although I am not sure where that assumption came from. I should've slowed down and verified the S/N on the data tag against the job card and not just use the S/N on the Job Card. Moving forward; I should also limit the number of days in a row I am working to prevent burnout or fatigue.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.