Flight Crew Air Transport Pilot (ATP)
Confusion; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency
Chart Or Publication; Procedure; MEL; Human Factors; Aircraft
[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.
Decision made to return to ZZZ; declared emergency; reviewed procedures for Overweight Landing and executed same. Landing; rollout and taxi in [was] uneventful. The status light and its relationship to the QRH are confusing as written.
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.