Narrative:

At about xa:30 am [early] morning during the installation of the thermocouple harnesses for the left engine of an emb-145 aircraft; my coworkers; aircraft maintenance technicians (amts) Y and Z; and I; technician X; decided to ask an inspector to look inside the engine before we started the closing procedures even though this was not required by the task we were accomplishing. At the time; I was on top of the engine pylon and verified that all the bolts on the top thermocouples and harness supports had been tightened. The inspector looked inside and noted that the harness cannon plugs had not been secured; but verified that all the leads had been correctly installed. At this time the only remaining work to be done was to connect the cannon plugs; seal them with heat shrink and connect three harness supports just aft of the cannon plugs. We decided that I would close the upper; outer bypass panels while technicians Y and Z readied the upper cowling. After that we would finish the job from the bottom. After the upper cowling was in place; I connected the outboard cannon plug from the bottom and asked coworker Y to shrink the heat shrink covering with a heat gun. Technician Y shrunk the heat shrink and I installed the inboard [cannon] plug. At this point we were interrupted by a lead mechanic who informed us of the need to move our plane so the other planes in the hangar could go out. I asked technician Y to verify that the inboard plug was tight since it was difficult to install and he checked it. While other mechanics were moving our airplane; technician Y mentioned that he was unable to verify that the [inboard] plug was tight because he couldn't get access to the plug. I made a mental note to check the plug again after the aircraft was back in the hangar. After the aircraft returned to the hangar I double checked that the inboard cannon plug was tight. I was satisfied with it and slid the heat shrink over the plug. Technician Y applied heat to it and I moved to the outboard side to take a last visual look that everything was in place. My visual scan was not in depth; mostly because I felt confident that inspector X had already looked at all the bolts and nuts. I verified that both cannon plugs were installed and sealed properly and looked for tools that might have been left behind. I did not notice at that time that the [harness] supports 6-10 inches aft of the cannon plugs were not secured. Technician Z followed close behind me to close up the outer bypass panels. We finished closing the engine and reinstalled the cowling. The rest of my shift was occupied with finishing paperwork; cleaning my workspace; helping to relocate the airplane to the gate; and returning tools to the parts department. I had only a few minutes to relax before leaving work. I returned home and immediately went to sleep. Later in the day I awoke with a sudden realization that I never secured the three harness supports (two inboard and one outboard) closest to the cannon plugs. The supports that were not connected had to remain disconnected so the cannon plugs could be maneuvered into position. After the inspector had look in the engine; technician Y suggested that I close the top outer bypass panels and then we could install the top cowling before hooking up the cannon plugs. At the time I had a desire to finish the installation of the harnesses before starting to close the panels; but I decided to go ahead with the suggestion because I needed one of my coworkers to operate the forklift to raise the upper cowling. I might have exercised more assertiveness since I was the mechanic taking responsibility for this task. The maintenance manual (M/M) reference for this task says to install and torque all the bolts for the harness supports and then to install the cannon plugs. This only possible if the cannon plugs are maneuvered into the space close to their installed position before installing the supports; but it would be difficult with a new piece of heat shrink over the harness. Moving the plane caused an interruption in the work flow and left my mind focused on making sure the left cannon plug was tight. My visual inspection later was incomplete because I felt confident that the inspector had already looked at all the bolts; even though I had noted earlier that these bolts were not installed because I had needed to slide the heat shrink tubing over the support to get everything in place. [Recommend] we should have waited till everything was secured before asking for an inspector to look at our work. This means I ought to have insisted that we finish all tasks related to securing the harnesses before starting to close any panels. I should have communicated clearly to my coworkers when our work was interrupted so that all of us would have known what was left to be completed and who would accomplish the remaining tasks when the airplane returned to the hangar. A change in the rolls royce [maintenance] manual (M/M) having the mechanic install the cannon plugs and heat shrink them before securing the last three supports would be helpful; but I don't think it would have prevented this incident. Graveyard shift. Memory-remembered later that bolts were not tightened.

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Original NASA ASRS Text

Title: Three Aircraft Maintenance Technicians (AMTs) report about their involvement installing thermocouple harnesses on Number 1 Engine after being informed that three harness supports were found not secured on an EMB-145 aircraft.

Narrative: At about XA:30 AM [early] morning during the installation of the thermocouple harnesses for the left engine of an EMB-145 aircraft; my coworkers; Aircraft Maintenance Technicians (AMTs) Y and Z; and I; Technician X; decided to ask an Inspector to look inside the engine before we started the closing procedures even though this was not required by the task we were accomplishing. At the time; I was on top of the engine pylon and verified that all the bolts on the top thermocouples and harness supports had been tightened. The Inspector looked inside and noted that the harness Cannon plugs had not been secured; but verified that all the leads had been correctly installed. At this time the only remaining work to be done was to connect the Cannon plugs; seal them with heat shrink and connect three harness supports just aft of the Cannon plugs. We decided that I would close the upper; outer bypass panels while Technicians Y and Z readied the upper cowling. After that we would finish the job from the bottom. After the upper cowling was in place; I connected the outboard Cannon plug from the bottom and asked coworker Y to shrink the heat shrink covering with a heat gun. Technician Y shrunk the heat shrink and I installed the inboard [Cannon] plug. At this point we were interrupted by a Lead Mechanic who informed us of the need to move our plane so the other planes in the hangar could go out. I asked Technician Y to verify that the inboard plug was tight since it was difficult to install and he checked it. While other mechanics were moving our airplane; Technician Y mentioned that he was unable to verify that the [inboard] plug was tight because he couldn't get access to the plug. I made a mental note to check the plug again after the aircraft was back in the hangar. After the aircraft returned to the hangar I double checked that the inboard Cannon plug was tight. I was satisfied with it and slid the heat shrink over the plug. Technician Y applied heat to it and I moved to the outboard side to take a last visual look that everything was in place. My visual scan was not in depth; mostly because I felt confident that Inspector X had already looked at all the bolts and nuts. I verified that both Cannon plugs were installed and sealed properly and looked for tools that might have been left behind. I did not notice at that time that the [harness] supports 6-10 inches aft of the Cannon plugs were not secured. Technician Z followed close behind me to close up the outer bypass panels. We finished closing the engine and reinstalled the cowling. The rest of my shift was occupied with finishing paperwork; cleaning my workspace; helping to relocate the airplane to the gate; and returning tools to the Parts Department. I had only a few minutes to relax before leaving work. I returned home and immediately went to sleep. Later in the day I awoke with a sudden realization that I never secured the three harness supports (two inboard and one outboard) closest to the Cannon plugs. The supports that were not connected had to remain disconnected so the Cannon plugs could be maneuvered into position. After the Inspector had look in the engine; Technician Y suggested that I close the top outer bypass panels and then we could install the top cowling before hooking up the Cannon plugs. At the time I had a desire to finish the installation of the harnesses before starting to close the panels; but I decided to go ahead with the suggestion because I needed one of my coworkers to operate the forklift to raise the upper cowling. I might have exercised more assertiveness since I was the Mechanic taking responsibility for this Task. The Maintenance Manual (M/M) reference for this task says to install and torque all the bolts for the harness supports and then to install the Cannon plugs. This only possible if the Cannon plugs are maneuvered into the space close to their installed position before installing the supports; but it would be difficult with a new piece of heat shrink over the harness. Moving the plane caused an interruption in the work flow and left my mind focused on making sure the Left Cannon plug was tight. My visual inspection later was incomplete because I felt confident that the Inspector had already looked at all the bolts; even though I had noted earlier that these bolts were not installed because I had needed to slide the heat shrink tubing over the support to get everything in place. [Recommend] we should have waited till everything was secured before asking for an Inspector to look at our work. This means I ought to have insisted that we finish all tasks related to securing the harnesses before starting to close any panels. I should have communicated clearly to my coworkers when our work was interrupted so that all of us would have known what was left to be completed and who would accomplish the remaining tasks when the airplane returned to the hangar. A change in the Rolls Royce [Maintenance] Manual (M/M) having the Mechanic install the Cannon plugs and heat shrink them before securing the last three supports would be helpful; but I don't think it would have prevented this incident. Graveyard shift. Memory-remembered later that bolts were not tightened.

Data retrieved from NASA's ASRS site 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.