Narrative:

[EICAS] status message - det turbulence ovht engine right about one hour into flight. Checked for message in QRH. Could not find. Relief pilot and first officer later checked and could not find either. Sent notification to dispatch. They requested we call [maintenance]. Upon [communication] patch with maintenance; it was determined that a cautionary landing was recommended. Maintenance stated there was no turbine overheat notification protection and therefore a landing [best] best course of action. Maintenance stated QRH required this for the indication. We stated we found no such status message in our QRH; but decided best course to follow maintenance and dispatch recommendation. Requested ATC course direct ZZZ and declared an emergency. Reviewed QRH procedures for an overweight landing and elected to do so. Landed on speed at 157 KTS/500 FPM descent rate at 552 K. Normal rollout. Remaining issue is why above status message not in QRH? Did find it in MEL under 77-3. If item can be flight crew placarded; why air interrupt the flight? [Recommend] update/correct QRH for above status message. Dispatch/maintenance recommendation inconsistent with MEL. However; we opted on the side of conservancy rather than continue. Indication malfunction.

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Original NASA ASRS Text

Title: Four pilots question why an air turnback was recommended by Maintenance when the same EICAS Status message for a Right Engine Turbine Overheat indication on their B777-200 aircraft could be placarded by the flight crew; in flight; under MEL 77-3. An emergency was also declared. No reference to status message in their QRH. Erratic Autothrottles on final also noted.

Narrative: [EICAS] Status message - DET TURB OVHT ENG R about one hour into flight. Checked for message in QRH. Could not find. Relief Pilot and First Officer later checked and could not find either. Sent notification to Dispatch. They requested we call [Maintenance]. Upon [communication] patch with Maintenance; it was determined that a cautionary landing was recommended. Maintenance stated there was no Turbine Overheat notification protection and therefore a landing [best] best course of action. Maintenance stated QRH required this for the indication. We stated we found no such status message in our QRH; but decided best course to follow Maintenance and Dispatch recommendation. Requested ATC course direct ZZZ and declared an emergency. Reviewed QRH procedures for an Overweight Landing and elected to do so. Landed on speed at 157 KTS/500 FPM descent rate at 552 K. Normal rollout. Remaining issue is why above status message not in QRH? Did find it in MEL under 77-3. If item can be flight crew placarded; why air interrupt the flight? [Recommend] update/correct QRH for above Status message. Dispatch/Maintenance recommendation inconsistent with MEL. However; we opted on the side of conservancy rather than continue. Indication malfunction.

Data retrieved from NASA's ASRS site as of July 2013 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.