Narrative:

Prior to gate departure asked for coffee. Flight attendant responded: 'yes; when you give us galley power.' we were on external power at the time so we checked throttles back and reset the utility buses. No hydraulics on; no fuel pumps on; no heavy load. Somewhere here the galleys are load shed. Ten minutes later; now on APU power; no coffee? Flight attendant's response: 'no coffee because no galley power!' ok throttles back; utility buses reset; no hydraulic pumps on no fuel pumps on; flight attendant says great again; they'll brew some coffee. You have galley power now? Flight attendant; 'yes'. Later; pushback engine start; no coffee? Utility buses no lights show powered up; hey long taxi how about that coffee? No galley power; load shed again? Hold on; reset utility buses; ok; do you have galley power or don't you? Flight attendant yes making your coffee. Level off no coffee; head back to use the lavatory and get coffee. Was this load shed function of the galley power possibly our first clue? After normal departure; climb out; just level planned initial cruise altitude FL320. Before sending the relief pilot to the cabin for scheduled break; I left the flight deck for a lavatory stop and cup of coffee; both first officers at the controls. After exiting the lavatory I was notified by the relief pilot; return to flight deck immediately; there was a problem. I missed the first event; but witnessed first hand the second; third; and fourth event at cruise altitude. The three events I witnessed the flap indicator moved slowly to one and the other two events the flap indicator suddenly snapped to indicate flaps 1. Captain and first officer's pfd's displayed red dashed lines and squares around: airspeed; attitude; and altitude; unreliable. Flap indicator showed flap movement and continued to flaps one position with flap handle confirmed stowed. A servo sound and a heavy thumping vibration accompanied these cycling indications/events in the cockpit. Right autopilot and auto throttle was engaged aircraft maintained altitude with very slight tendency to pitch up during start of these events. However; the auto throttle commanded the throttles close at least twice. The first officer guarded the flight controls; to maintain level flight and speed control. After the second event; I briefed the first officer on our first usable divert option. Then established communications with dispatch desk. Through a three way communication consulted with maintenance. This was an 'unconventional event;' -not covered by the QRH. Maintenance control directed us to switch to our alternate air data computer. However; during the third event; results were the same with complete blanking of all the flat panel displays. During the third event there was an intermittent EICAS caution that transited the upper EICAS display; not visible long enough to identify a hard error. The flap indicator was indicating the flaps were extended to flaps 1. Our weather radar indications were spiking. The servo sounds and heavy thumping vibration felt in the flight deck floor boards and center pedestal were intriguing. At this point I let dispatch know we were going to divert. I declared a 'mayday; mayday; mayday' emergency with center. We were cleared to descend to FL100 and orbit over an initial NAVAID fix. During this period of time the servo sound and thumping vibration was very distracting. There were no more flight instrument display issues or servo sounds after this point (flaps extended to flaps 1); so stopped our descent at 14;500 and climbed back to FL180. Departed orbit and proceeded to departure airport with plan to land on runway 28. Maintenance control then asked about the noises; servo; and thump? The servo sounded like the trim running on a 727 and would stop followed by some kind of thump which we felt through our feet and the center throttle quadrant and pedestal? Relief pilot leaning forward helping out said he felt thump in pedestal. The servo sound he said actually came from overhead; an ecu? What's that? It's overhead part of the bus switching relays 'you may have something wrong with standby power or a TR control' ...really? Was our first clue in the breakdown of what ever was wrong -the shy load shed of galleys? The day after this event as we departed; I saw the aircraft's left engine cowls opened and mechanics taking pictures of what they described as burnt power leads out of the left idg.

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Original NASA ASRS Text

Title: A B767-300 experienced load shedding during preflight and inflight. Also inflight; intermittent flight instrument anomalies; brief EICAS messages and false flap extension indications occurred. An emergency was declared and the aircraft returned to the departure airport where a loose IDG lead was discovered.

Narrative: Prior to gate departure asked for coffee. Flight Attendant responded: 'Yes; when you give us galley power.' We were on external power at the time so we checked throttles back and reset the utility buses. No hydraulics on; no fuel pumps on; no heavy load. Somewhere here the galleys are load shed. Ten minutes later; now on APU power; No coffee? Flight Attendant's response: 'No coffee because no galley power!' OK throttles back; utility buses reset; no hydraulic pumps on no fuel pumps on; Flight Attendant says great again; they'll brew some coffee. You have galley power now? Flight Attendant; 'yes'. Later; pushback engine start; no coffee? Utility buses no lights show powered up; hey long taxi how about that coffee? No galley power; load shed again? Hold on; reset utility buses; OK; do you have galley power or don't you? Flight Attendant yes making your coffee. Level off no coffee; head back to use the lavatory and get coffee. Was this load shed function of the galley power possibly our first clue? After normal departure; climb out; just level planned initial cruise altitude FL320. Before sending the Relief Pilot to the cabin for scheduled break; I left the flight deck for a lavatory stop and cup of coffee; both First Officers at the controls. After exiting the lavatory I was notified by the Relief Pilot; return to flight deck immediately; there was a problem. I missed the first event; but witnessed first hand the second; third; and fourth event at cruise altitude. The three events I witnessed the flap indicator moved slowly to one and the other two events the flap indicator suddenly snapped to indicate flaps 1. Captain and First Officer's PFD's displayed red dashed lines and squares around: airspeed; attitude; and altitude; unreliable. Flap indicator showed flap movement and continued to flaps one position with flap handle confirmed stowed. A servo sound and a heavy thumping vibration accompanied these cycling indications/events in the cockpit. Right autopilot and auto throttle was engaged aircraft maintained altitude with very slight tendency to pitch up during start of these events. However; the auto throttle commanded the throttles close at least twice. The First Officer guarded the flight controls; to maintain level flight and speed control. After the second event; I briefed the First Officer on our first usable divert option. Then established communications with Dispatch desk. Through a three way communication consulted with Maintenance. This was an 'unconventional event;' -not covered by the QRH. Maintenance Control directed us to switch to our alternate Air Data Computer. However; during the third event; results were the same with complete blanking of all the flat panel displays. During the third event there was an intermittent EICAS caution that transited the upper EICAS display; not visible long enough to identify a hard error. The flap indicator was indicating the flaps were extended to flaps 1. Our weather radar indications were spiking. The servo sounds and heavy thumping vibration felt in the flight deck floor boards and center pedestal were intriguing. At this point I let Dispatch know we were going to divert. I declared a 'Mayday; mayday; mayday' emergency with Center. We were cleared to descend to FL100 and orbit over an initial NAVAID fix. During this period of time the servo sound and thumping vibration was very distracting. There were no more flight instrument display issues or servo sounds after this point (flaps extended to Flaps 1); so stopped our descent at 14;500 and climbed back to FL180. Departed orbit and proceeded to departure airport with plan to land on Runway 28. Maintenance Control then asked about the noises; servo; and thump? The servo sounded like the trim running on a 727 and would stop followed by some kind of thump which we felt through our feet and the center throttle quadrant and pedestal? Relief Pilot leaning forward helping out said he felt thump in pedestal. The servo sound he said actually came from overhead; an ECU? What's that? It's overhead part of the bus switching relays 'you may have something wrong with standby power or a TR control' ...Really? Was our first clue in the breakdown of what ever was wrong -the shy load shed of galleys? The day after this event as we departed; I saw the aircraft's left engine cowls opened and mechanics taking pictures of what they described as burnt power leads out of the left IDG.

Data retrieved from NASA's ASRS site as of April 2012 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.