B767-400 and 400 ER
Maintenance Powerplant; Maintenance Airframe; Maintenance Avionics
Maintenance Avionics 27; Maintenance Technician 27
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Flight Crew Diverted; General Flight Cancelled / Delayed
Human Factors; Procedure; Equipment / Tooling; Aircraft
During maintenance in March 2013 on # 2 Engine on a B767 aircraft in the area of the # 6 bearing scavenge area; a parts bag which was used to cover the scavenge opening to prevent FOD from entering the tube was inadvertently left in place after maintenance was completed. This caused the engine to lose oil during a flight in November 2013 which led to the flight diverting. The problem was that improper equipment was used during the maintenance in the # 6 bearing cavity area. This can be prevented in the future by manufacturing a cover with a highly visible marker/streamer to cover the scavenge tube port during maintenance.
Reporter stated the # 6 bearing is the aft bearing position on the CF-6 Engine. He (reporter) is part of an Engine Troubleshooting Crew that does Periodic Checks on the CF-6 Engine's aft bearing oil spray nozzles; the nozzles tend to coke up and prevents oil from being sprayed on the # 6 bearing. After removing the engine tailcone and inner oil bearing cavity cover; a square; beveled drain opening and lower connecting drain tube are exposed at the six o'clock position inside the cavity. The oil drains into the oil return line which is part of the scavenge oil return system. To prevent any possibility of FOD (bolts; washers; nuts) falling into the drain opening and drain tube; mechanics were installing a cloth parts bag into opening. Reporter stated the parts bag was temporarily installed after they had performed their initial air pressure flow check of the oil supply nozzle and drain return line; but not removed. During the flight; the CF-6 engine did not lose all the oil; but had low oil pressure. The engine was shutdown; the aircraft diverted with a full load of passengers; requiring another aircraft to be sent to fly passengers out and another engine ferried in. The parts bag is a coarse; porous weaved cloth and was initially thought to have eventually coked-up; causing the oil to accumulate inside the bearing cavity and finally blowing oil out through the breather tube at the aft end of the engine. But; he believes the parts bag eventually got twisted up enough inside the drain tube and plugged the tube. The same Troubleshooting Crew found the problem by boroscoping the drain tube. His Air Carrier has since designed a special plug; with long red streamers; that installs into and over the drain opening.
An Aircraft Maintenance Technician (AMT) reports that a B767 aircraft lost oil in # 2 Engine in flight; approximately eight months after a cloth parts bag had been installed; but not removed. The bag was used to cover the # 6 bearing cavity drain opening for the scavenge oil return line. Flight diverted.