B747-C/F
Flight Crew Flight Engineer; Maintenance Powerplant; Maintenance Airframe
Communication Breakdown; Training / Qualification; Situational Awareness; Troubleshooting; Confusion; Human-Machine Interface
Aircraft Equipment Problem Critical
General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Procedure; Human Factors; Company Policy
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.
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.