Narrative:

I was given the assignment of replacing the integrated drive generator (idg) air/oil heat exchanger/cooler valve on a B-777 aircraft. This was a borrowed part and needed to be returned. When I received the job I noticed three things right away: 1) it did not say what engine had the borrowed part. 2) the part numbers did not match on the borrowed part and the part I was going to install. 3) it was supposed to take one hour to be accomplished. We were shorthanded that night. I went to see my supervisor and he did search on [maintenance] history and found out the borrowed part was on the # 1 engine. After doing more search on my own; I found out that air carrier X had borrowed the cooler valve but not the heat exchanger and air carrier X did not have the cooler valve in stock; but instead air carrier X had the whole unit in stock; heat exchanger and cooler valve and this is the reason I had two different part numbers. So what I needed to do was to remove the unit and take it apart once it was off the engine and route it to stores for the proper return and shipping procedures and install the new unit.I started feeling pressure because I had a lot work ahead of me. I was working by myself; it was very late and I did not even have the engine open because of the above issues. I printed the maintenance manual for removal and installation; removed the unit and I was in the process of installing the new unit when quality control showed up to my engine. They asked for the maintenance manual and I provided them with it. They came back a second time and he alerted me that I had forgotten to deactivate the thrust reverser valve and that everything in the cockpit was good (tagged and breakers pulled). I came back to the hangar and pulled the maintenance manual to deactivate the reverser. Once I had the reverser deactivated I completed my job. Today; a month later; I sat down with my supervisor and I was told that not doing the [reverser deactivation] step became a rule violation finding. I understand it was my fault; but there were plenty of contributing factors that made me lose my focus that night.

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Original NASA ASRS Text

Title: A Mechanic reports a schedule replacement of a borrowed cooler valve on the #1 engine of a B777 aircraft resulted in replacing the entire Integrated Drive Generator (IDG) Air/Oil Heat Exchanger and Cooler Valve; during which a safety step was missed. Lack of manpower; additional maintenance history search requirements; and having to return to the hangar for Maintenance Manual information were contributing factors.

Narrative: I was given the assignment of replacing the Integrated Drive Generator (IDG) Air/Oil Heat Exchanger/Cooler Valve on a B-777 aircraft. This was a borrowed part and needed to be returned. When I received the job I noticed three things right away: 1) It did not say what engine had the borrowed part. 2) The Part Numbers did not match on the borrowed part and the part I was going to install. 3) It was supposed to take one hour to be accomplished. We were shorthanded that night. I went to see my Supervisor and he did search on [Maintenance] history and found out the borrowed part was on the # 1 engine. After doing more search on my own; I found out that Air Carrier X had borrowed the cooler valve but not the heat exchanger and Air Carrier X did not have the cooler valve in stock; but instead Air Carrier X had the whole unit in stock; heat exchanger and cooler valve and this is the reason I had two different Part Numbers. So what I needed to do was to remove the unit and take it apart once it was off the engine and route it to Stores for the proper return and shipping procedures and install the new unit.I started feeling pressure because I had a lot work ahead of me. I was working by myself; it was very late and I did not even have the engine open because of the above issues. I printed the Maintenance Manual for Removal and Installation; removed the unit and I was in the process of installing the new unit when Quality Control showed up to my engine. They asked for the Maintenance Manual and I provided them with it. They came back a second time and he alerted me that I had forgotten to deactivate the Thrust Reverser Valve and that everything in the cockpit was good (tagged and breakers pulled). I came back to the hangar and pulled the Maintenance Manual to deactivate the reverser. Once I had the reverser deactivated I completed my job. Today; a month later; I sat down with my Supervisor and I was told that not doing the [reverser deactivation] step became a rule violation finding. I understand it was my fault; but there were plenty of contributing factors that made me lose my focus that night.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.