B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Aircraft Equipment Problem Dissipated; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
During the takeoff roll; above 100 KTS; the L Eng PRV EICAS message illuminated with a left engine BLEED light and an associated L Eng PRV status message. Followed QRH procedure and turned off the left engine bleed air switch. Called Dispatch; talked to Maintenance Control and decided to continue to destination. Two hours into the flight while at FL340 the R Eng HPSOV EICAS message illuminated with an associated R Eng HPSOV status message. Right pneumatic duct pressure remained normal at 39 PSI. The QRH procedure directed to turn the right engine bleed air switch off. I elected to leave the right engine bleed air switch on to prevent an unwanted depressurization and I declared an emergency and began to descend and divert to a nearby airport while we started the APU as a backup pneumatic source below 17;000 FT. Called Dispatch and Maintenance Control again and Maintenance advised that; with normal duct pressure; the now intermittent R Eng HPSOV message was probably an indication problem. He also advised taking the aircraft back to our departure airport due to superior maintenance capability. With Dispatch concurrence; I decided to return. Following descent below 17;000 FT MSL we followed the QRH procedure and turned the right engine bleed switch off. We landed uneventfully and below max landing weight upon arrival.
A B767-300ER ultimately returned to their departure airport after experiencing EICAS pneumatic system bleed anomalies on both engines.