Narrative:

Operating flight upon pushback; #3 engine egt digital and pointer systems malfunctioned on start. We made a logbook entry and returned to the blocks. Maintenance told us they were ordering two egt harnesses. Upon arrival to the airplane on the next day; we were advised that the airplane was repaired. I was reassigned to a different captain and first officer to operate this flight. We pushed and started the process of starting all 4 engines for taxi. Upon starting #3 engine; I noted the egt digital and pointer systems were still erratically sticking during the start. Since we couldn't verify the condition of #3 engine; we elected to shut down the engine for taxi back to the spot. When we got to the parking spot; maintenance came aboard; decided to swap the egt harnesses from #4 to #3 engine for troubleshooting; and elected to run the engine. Their engine run produce negative results; as the engine produced the same erratic egt during their run. After the ground run by maintenance; I went downstairs to try to learn from them what their thoughts were; and witnessed an egt harness laying on the ground. It had a thick coating of red rtv/silicone on it near the connector. I asked one of the mechanics; if that was the 'bad harness.' he stated 'no; that's the harness off the spare engine from another airport. We had to repair it because it was cracked. We only got one harness'. Shortly afterward; we were informed via the satphone that we were released back to the hotel for rest; as the airplane was aog. I was told after rest that the mechanics had bore-scoped the engine; and found fan blades worn out of limits. After seeing the same results two nights in a row; I knew there was going to be a problem. Maintenance in the field made the facts very clear. I believe this event could have been catastrophic. Based on the weather conditions at the scheduled takeoff; the takeoff N1 was 116.9%. We were at maximum gross weight for takeoff. Maintenance never runs the engines at that power setting; due to restrictions based on static airflow. Had the engine failed at or above V1; the results could have been very bad. I don't know if there was pressure from maintenance supervision or not; but there was certainly a breakdown between maintenance control and the line maintenance. The fact that two leads were ordered; only one arrived; and it was already cracked when it got there contributed to this incident. Additionally; the unauthorized field repair of the single egt lead from the other station was a factor. Maintenance has to be held to a higher standard. If serviceable parts aren't available; unserviceable parts should never be installed on an airplane. I don't think this incident was a result of bad communication. I think this act was intentional. Additionally; as I understand the situation; the mechanic that was supposed too fly with us was made to make the sign off. I don't believe he would have normally signed off a discrepancy he supervised; but knew was bad. He didn't directly make the installation; but supervised it; so he was made to sign it off. The persons directly involved should be held accountable for the potential loss of the airplane.

Google
 

Original NASA ASRS Text

Title: A B747F Flight Engineer reported that on two consecutive nights the same aircraft's #3 Engine EGT gauge indicated an abnormal start even with a replaced EGT harness; so the flight was canceled and he was later told the fan blades were worn out of limits.

Narrative: Operating flight upon pushback; #3 engine EGT digital and pointer systems malfunctioned on start. We made a logbook entry and returned to the blocks. Maintenance told us they were ordering two EGT harnesses. Upon arrival to the airplane on the next day; we were advised that the airplane was repaired. I was reassigned to a different Captain and First Officer to operate this flight. We pushed and started the process of starting all 4 engines for taxi. Upon starting #3 engine; I noted the EGT digital and pointer systems were still erratically sticking during the start. Since we couldn't verify the condition of #3 engine; we elected to shut down the engine for taxi back to the spot. When we got to the parking spot; Maintenance came aboard; decided to swap the EGT harnesses from #4 to #3 engine for troubleshooting; and elected to run the engine. Their engine run produce negative results; as the engine produced the same erratic EGT during their run. After the ground run by Maintenance; I went downstairs to try to learn from them what their thoughts were; and witnessed an EGT harness laying on the ground. It had a thick coating of red RTV/silicone on it near the connector. I asked one of the Mechanics; if that was the 'bad harness.' He stated 'no; that's the harness off the spare engine from another airport. We had to repair it because it was cracked. We only got one harness'. Shortly afterward; we were informed via the SATPHONE that we were released back to the hotel for rest; as the airplane was AOG. I was told after rest that the mechanics had bore-scoped the engine; and found fan blades worn out of limits. After seeing the same results two nights in a row; I knew there was going to be a problem. Maintenance in the field made the facts very clear. I believe this event could have been catastrophic. Based on the weather conditions at the scheduled takeoff; the takeoff N1 was 116.9%. We were at maximum gross weight for takeoff. Maintenance never runs the engines at that power setting; due to restrictions based on static airflow. Had the engine failed at or above V1; the results could have been very bad. I don't know if there was pressure from maintenance supervision or not; but there was certainly a breakdown between Maintenance Control and the Line Maintenance. The fact that two leads were ordered; only one arrived; and it was already cracked when it got there contributed to this incident. Additionally; the unauthorized field repair of the single EGT lead from the other station was a factor. Maintenance has to be held to a higher standard. If serviceable parts aren't available; unserviceable parts should never be installed on an airplane. I don't think this incident was a result of bad communication. I think this act was intentional. Additionally; as I understand the situation; the mechanic that was supposed too fly with us was made to make the sign off. I don't believe he would have normally signed off a discrepancy he supervised; but knew was bad. He didn't directly make the installation; but supervised it; so he was made to sign it off. The persons directly involved should be held accountable for the potential loss of the airplane.

Data retrieved from NASA's ASRS site as of July 2013 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.