B777 Undifferentiated or Other Model
Flight Crew Last 90 Days 200; Flight Crew Total 24000; Flight Crew Type 5000
Aircraft Equipment Problem Less Severe
Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action; General Maintenance Action; General Declared Emergency
Aircraft
After takeoff and upon acceleration and clean-up at 800 FT; I noted that I had no down trim on the electric yoke trim. Queried First Officer and he too had no forward trim. Only aft trim was available. I elected to maintain present speed and retain the flaps at flaps 1; 220 KTS to avoid major configuration changes which might jeopardize pitch control. ATC quickly allowed us to maintain a lower altitude and assigned a west heading so that we might assess the situation. A review of all switches and circuit breakers gave no clues. There were no cockpit (EICAS or Status) messages or indications. CRM was working well with good input from both First Officers. Our concern was that with only aft electric trim and no down trim we could enter an unsustainable flight condition; so we elected to operate without the autopilot; continuing to hand-fly; to preclude it trimming itself beyond its capability. While working the problem our SAT phone did not work. It kept dropping off while trying to contact Dispatch; going into a low priority Que state. Also; the FMC kept timing out. We elected to dump fuel to landing weight and return to [our departure airport]. We slowly configured to landing; with slow speed changes. The ALT trim worked well. We asked for equipment to standby; and give a quick look to the aircraft when we exited the runway; prior to proceeding to the gate. VHF communication with Tower and Approach was excellent and their response was fast and most helpful. We were granted a long (20 NM) approach and slow approach speed to accommodate a gentle reconfiguration. All went well on approach and landing. During descent; the electric trim seemed to momentarily have some effect; thought the trim indicator did not follow trim input and electric nose down trim resulted in a barely discernible nose down pitch. After an uneventful landing; electric trim appeared to operate normally; with indicator following inputs in both directions. In our post flight review; there were no substantive changes we would have made to our event. Hand-flying was made easier by good crew communication and helpful input. Both First Officers were exemplary in their comportment: Helpful; full of good input; and steadily working the problem to its conclusion.
As Relief Pilot I monitored fuel dumping operations and made annoucements to the passengers and talked to flight attendant crew. Crew coordination was very good and we started the APU just in case of any electrical problems. I did landing data with no speedbrakes since Dispatch could not give us any data via ACARS. The landing was uneventful and fire trucks looked us over with no problems in the flight controls or brakes. We taxied to the gate and had no problems.
After takeoff both B777 yoke controlled nose down trim inputs failed; although the ALT Trim continued to function; so an emergency was declared and the flight returned to the departure airport.