Narrative:

As we prepared the performance computations for the flight; we were a relatively light B777B for our short domestic flight. The first officer set the zero wind assumed temperature of 54 degrees in the thrust limit page. The thrust reference mode annunciation of the top EICAS indicated climb correctly. After engine start the thrust reference mode changed from climb to climb 2 on its own. The assumed temperature remained at 54 degrees C. The performance was climb thrust limited; note the C after the EPR. The zero wind line of the ACARS runway data indicated: 0 1.31C 84 415.9 130/54 OAT at ZZZ was 44 degrees F (6 degrees C) tog was 405 and ZFW was 369. This was relayed to the fleet after the event for information. Also this was the same type event; by another reporter on another P model B777.callback conversation with reporter revealed the following information: the reporter stated that his company does not use reduced climb in any operation for this aircraft. They have recently changed the acceptable reduced takeoff temperature settings to allow the use of assumed temperatures up to 65 degrees. Incidents of this type appear random and isolated and he noted that in this case the shift occurred at the power shift from the APU to engine generators. There is no checklist item following engine start that would lead to rechecking the settings that are previously checked and briefed.

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Original NASA ASRS Text

Title: A B777 CREW NOTES AN UNCOMMANDED CHANGE OF THE THRUST SETTING TO REDUCED CLB PWR AFTER ENGINES WERE STARTED AND ELECTRICAL PWR SHIFTED TO ENG GENERATORS.

Narrative: AS WE PREPARED THE PERFORMANCE COMPUTATIONS FOR THE FLT; WE WERE A RELATIVELY LIGHT B777B FOR OUR SHORT DOMESTIC FLT. THE FO SET THE ZERO WIND ASSUMED TEMP OF 54 DEGS IN THE THRUST LIMIT PAGE. THE THRUST REFERENCE MODE ANNUNCIATION OF THE TOP EICAS INDICATED CLB CORRECTLY. AFTER ENGINE START THE THRUST REFERENCE MODE CHANGED FROM CLB TO CLB 2 ON ITS OWN. THE ASSUMED TEMP REMAINED AT 54 DEGS C. THE PERFORMANCE WAS CLB THRUST LIMITED; NOTE THE C AFTER THE EPR. THE ZERO WIND LINE OF THE ACARS RWY DATA INDICATED: 0 1.31C 84 415.9 130/54 OAT AT ZZZ WAS 44 DEGS F (6 DEGS C) TOG WAS 405 AND ZFW WAS 369. THIS WAS RELAYED TO THE FLEET AFTER THE EVENT FOR INFORMATION. ALSO THIS WAS THE SAME TYPE EVENT; BY ANOTHER RPTR ON ANOTHER P MODEL B777.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT HIS COMPANY DOES NOT USE REDUCED CLB IN ANY OPERATION FOR THIS ACFT. THEY HAVE RECENTLY CHANGED THE ACCEPTABLE REDUCED TKOF TEMPERATURE SETTINGS TO ALLOW THE USE OF ASSUMED TEMPERATURES UP TO 65 DEGS. INCIDENTS OF THIS TYPE APPEAR RANDOM AND ISOLATED AND HE NOTED THAT IN THIS CASE THE SHIFT OCCURRED AT THE POWER SHIFT FROM THE APU TO ENG GENERATORS. THERE IS NO CHECKLIST ITEM FOLLOWING ENGINE START THAT WOULD LEAD TO RECHECKING THE SETTINGS THAT ARE PREVIOUSLY CHECKED AND BRIEFED.

Data retrieved from NASA's ASRS site as of May 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.