When you assume that you have the right parts and you assume they are going on the correct engine, what could go wrong? Verification of the paperwork associated with the job could have saved a lot of time, labor and embarrassment in this wrong engine, wrong parts incident.
I started my service on [a B737 aircraft]…#1 engine. Another AMT was to start the fuel nozzle replacement. After I completed my service, I noticed the #2 engine cowlings were opened up so I assumed that must be the engine getting the fuel nozzles…. When the nozzles arrived, one AMT took the left side of the engine and another took the right side and they began removing the fuel nozzles
to replace them. I was the third person so I was handing tools to them and getting whatever they needed….
After the Inspector had checked the engine for safety and security, I closed the #2 engine cowlings. It wasn’t until the next day that I was informed that the nozzles were the wrong part number and the work was supposed to have been done on the #1 engine. I had never looked at any of the paperwork to verify the part numbers or which engine we were supposed to work on.