A B767-300's EICAS alerted L ENG EEC C1 during climb followed later by alert L ENG CONTROL and the engine spooling down to minimum fuel flow. An emergency was declared and the aircraft returned to the departure airport.

Narrative

I was the Captain on the flight. During the preflight review of the maintenance history; we noticed this airplane had been refused the previous day because of an Electronic Engine Control (EEC) status message. It appeared Maintenance had replaced the left EEC and the airplane was returned to service. There was some discussion among the crew about the implications of a loss of the EEC and our ETOPS operation. Upon inspection of the Maintenance Release Document (MRD); there was an entry indicating a deferral of a status message that seemed to be appearing intermittently. We had no status messages at that time and assumed it had been repaired. There was some discussion about why there was a deferral and no message. Again; after review of the Release we noticed the left engine EEC had been replaced and everything appeared normal. We continued our preflight preparations. We pushed back and started both engines. Before taxi we noticed the status message 'L ENG EEC C1' had appeared. We contacted Maintenance and discussed the message and were convinced the message was erroneous and thus the reason for the deferral. We decided as a crew that the flight could continue safely. Taxi and takeoff were uneventful. As we continued our climb; I noticed a status message alert indication and noticed a 'L ENG CONTROL' message now included with the 'L ENG EEC C1' message. We contacted Dispatch and Maintenance. We began discussing the new message with the Maintenance Controller. As we leveled off at 33;000 FT; the left engine spooled down to minimum fuel flow. We quickly reviewed our situation; declared an emergency; and decided to return to the departure airport. We needed about 10 minutes to dump enough fuel to prevent an overweight landing. We used that time to run all the appropriate checklists and set up a single engine approach to the runway. I advised the Purser to prepare the cabin for evacuation. The plan was to touchdown as early as possible; use aerodynamic braking and reverse thrust to 80 KTS and apply brakes as required. We landed without incident. After we cleared the runway; the Airport Rescue and Fire Fighters inspected the landing gear and engines. We continued to the gate. After we completed the parking checklist; we noticed the 'L ENG SPEED CARD' status message now also displayed. This entire incident was an excellent exercise in crew communication and coordination. We had an FAA Inspector conducting an ETOPS line check. He joined in the discussions and we welcomed his input. He maintained a listening watch on all our cockpit and radio communications.