Narrative:

While cruising at FL390 we received an EICAS message 'right engine second cont' indicating the secondary channel of the eec had failed on the right engine. A short time later (10 mins or so?) we received a second EICAS message 'right engine pri cont' indicating the primary channel of the eec had also failed on the right engine. The autothrottles disconnected at that time. The right engine continued operating at about 72% N1; but was not responsive to throttle movement. We checked the QRH for procedures for these failures. We notified dispatch of the problem and that we were diverting to ZZZ. Since the right engine continued to operate at around 72% N1 in cruise; I thought I might have to shut the engine down in the descent in order to be able to slow for landing. I also thought I would have to shut it down if the RPM became unstable. Therefore we reviewed all single engine approach and go around procedures; briefed the flight attendants and passenger; declared an emergency and requested the airport emergency equipment. As we descended and slowed down; the right engine N1 RPM also gradually decreased; so that it was unnecessary to shut the engine down for the approach. The approach and landing were otherwise uneventful. I shut the right engine down after clearing the runway and taxied to the gate.

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Original NASA ASRS Text

Title: A B757-200 R ENG PRIMARY AND SECONDARY ENG ELECTRONIC CTL SYS FAIL LIGHTS ILLUMINATED IN FLT. FLT DIVERTED TO AN ENRTE ARPT.

Narrative: WHILE CRUISING AT FL390 WE RECEIVED AN EICAS MESSAGE 'R ENG SEC CONT' INDICATING THE SECONDARY CHANNEL OF THE EEC HAD FAILED ON THE R ENG. A SHORT TIME LATER (10 MINS OR SO?) WE RECEIVED A SECOND EICAS MESSAGE 'R ENG PRI CONT' INDICATING THE PRIMARY CHANNEL OF THE EEC HAD ALSO FAILED ON THE R ENG. THE AUTOTHROTTLES DISCONNECTED AT THAT TIME. THE R ENG CONTINUED OPERATING AT ABOUT 72% N1; BUT WAS NOT RESPONSIVE TO THROTTLE MOVEMENT. WE CHKED THE QRH FOR PROCS FOR THESE FAILURES. WE NOTIFIED DISPATCH OF THE PROB AND THAT WE WERE DIVERTING TO ZZZ. SINCE THE R ENG CONTINUED TO OPERATE AT AROUND 72% N1 IN CRUISE; I THOUGHT I MIGHT HAVE TO SHUT THE ENG DOWN IN THE DSCNT IN ORDER TO BE ABLE TO SLOW FOR LNDG. I ALSO THOUGHT I WOULD HAVE TO SHUT IT DOWN IF THE RPM BECAME UNSTABLE. THEREFORE WE REVIEWED ALL SINGLE ENG APCH AND GAR PROCS; BRIEFED THE FLT ATTENDANTS AND PAX; DECLARED AN EMER AND REQUESTED THE ARPT EMER EQUIP. AS WE DSNDED AND SLOWED DOWN; THE R ENG N1 RPM ALSO GRADUALLY DECREASED; SO THAT IT WAS UNNECESSARY TO SHUT THE ENG DOWN FOR THE APCH. THE APCH AND LNDG WERE OTHERWISE UNEVENTFUL. I SHUT THE R ENG DOWN AFTER CLRING THE RWY AND TAXIED TO THE GATE.

Data retrieved from NASA's ASRS site as of January 2009 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.