Narrative:

We departed hkg on time and flew a normal departure and climb out to FL370. The autoplt and autothrottles were engaged around FL230 and operated normally. Prior to reaching rvsm airspace, the pms was turned off -- we flew in altitude hold and mach hold until the incident occurred. We were light -- 525000 pounds -- with 206 passenger and 13 crew on board. We cruised at FL370 for approximately 20 mins in smooth air. The flight plan called for FL410 over taiwan and because of slight turbulence at FL370, we climbed to FL410. We were 1100 ft above optimum and 3000+ ft below maximum altitude. After cruising at FL410 for a short time, the autothrottles clicked off on their own. I tried to reengage mach hold but could not select it. I then asked the so to check for circuit breakers. He found 2 for the autothrottle system (ats). I instructed him to pull and reset both circuit breakers. After they were reset, I was able to reselect mach hold, which I did and turned on the autothrottle switch on the mode control panel. The throttles seemed to operate normally for a few moments, but then commanded a retard toward idle. I clicked off the ats and advanced the thrust levers. Only engines #2 and #3 advanced, while engines #1 and #4 continued to unspool to idle. I then went to maximum continuous thrust on engines #2 and #3. The so had already turned on continuous ignition and I turned on the seat belt sign at this point. In order to maintain mach, we requested from naha control an immediate descent to FL370 which we received. I dumped the nose as the first officer and so performed the procedure for 'engines not responding to thrust lever movement.' both engines recovered prior to reaching FL370. There were some altitude oscillations as I leveled at FL370 due to the high rate of descent I earlier had. Later, I talked to the purser and made a PA to reassure the passenger. There were no compressor stalls or engine exceedences during the incident. Note: it should be noted that prior to the flight, there was an MEL sticker in the front of the logbook and at the autothrottle switch. There was no MEL listed on the release and no lids entry in the logbook. The sticker in the front of the logbook stated: 'autothrottle use in approach mode only' but there was no MEL noted on the sticker. We asked hkg maintenance about this and they came back - took the stickers off and said there was no problem -- they said that an earlier problem with throttles had been signed off on sep/thu/04, which we noted in previous log pages. Also note that there had been a previous incident of the #1 engine not responding to thrust lever movement after a descent.

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Original NASA ASRS Text

Title: IMMEDIATE DSCNT FROM FL410 TO FL370 REQUESTED BY THE PIC OF A B747-200 WHEN #1 AND #4 ENGS GO TO FLT IDLE AFTER AN INITIAL MOVEMENT OF ALL THROTTLES TOWARDS A RETARD POS WHILE ON AUTOTHROTTLE. FLT WAS ON FREQ WITH RORG CTL.

Narrative: WE DEPARTED HKG ON TIME AND FLEW A NORMAL DEP AND CLBOUT TO FL370. THE AUTOPLT AND AUTOTHROTTLES WERE ENGAGED AROUND FL230 AND OPERATED NORMALLY. PRIOR TO REACHING RVSM AIRSPACE, THE PMS WAS TURNED OFF -- WE FLEW IN ALT HOLD AND MACH HOLD UNTIL THE INCIDENT OCCURRED. WE WERE LIGHT -- 525000 LBS -- WITH 206 PAX AND 13 CREW ON BOARD. WE CRUISED AT FL370 FOR APPROX 20 MINS IN SMOOTH AIR. THE FLT PLAN CALLED FOR FL410 OVER TAIWAN AND BECAUSE OF SLIGHT TURB AT FL370, WE CLBED TO FL410. WE WERE 1100 FT ABOVE OPTIMUM AND 3000+ FT BELOW MAX ALT. AFTER CRUISING AT FL410 FOR A SHORT TIME, THE AUTOTHROTTLES CLICKED OFF ON THEIR OWN. I TRIED TO REENGAGE MACH HOLD BUT COULD NOT SELECT IT. I THEN ASKED THE SO TO CHK FOR CIRCUIT BREAKERS. HE FOUND 2 FOR THE AUTOTHROTTLE SYS (ATS). I INSTRUCTED HIM TO PULL AND RESET BOTH CIRCUIT BREAKERS. AFTER THEY WERE RESET, I WAS ABLE TO RESELECT MACH HOLD, WHICH I DID AND TURNED ON THE AUTOTHROTTLE SWITCH ON THE MODE CTL PANEL. THE THROTTLES SEEMED TO OPERATE NORMALLY FOR A FEW MOMENTS, BUT THEN COMMANDED A RETARD TOWARD IDLE. I CLICKED OFF THE ATS AND ADVANCED THE THRUST LEVERS. ONLY ENGS #2 AND #3 ADVANCED, WHILE ENGS #1 AND #4 CONTINUED TO UNSPOOL TO IDLE. I THEN WENT TO MAX CONTINUOUS THRUST ON ENGS #2 AND #3. THE SO HAD ALREADY TURNED ON CONTINUOUS IGNITION AND I TURNED ON THE SEAT BELT SIGN AT THIS POINT. IN ORDER TO MAINTAIN MACH, WE REQUESTED FROM NAHA CTL AN IMMEDIATE DSCNT TO FL370 WHICH WE RECEIVED. I DUMPED THE NOSE AS THE FO AND SO PERFORMED THE PROC FOR 'ENGS NOT RESPONDING TO THRUST LEVER MOVEMENT.' BOTH ENGS RECOVERED PRIOR TO REACHING FL370. THERE WERE SOME ALT OSCILLATIONS AS I LEVELED AT FL370 DUE TO THE HIGH RATE OF DSCNT I EARLIER HAD. LATER, I TALKED TO THE PURSER AND MADE A PA TO REASSURE THE PAX. THERE WERE NO COMPRESSOR STALLS OR ENG EXCEEDENCES DURING THE INCIDENT. NOTE: IT SHOULD BE NOTED THAT PRIOR TO THE FLT, THERE WAS AN MEL STICKER IN THE FRONT OF THE LOGBOOK AND AT THE AUTOTHROTTLE SWITCH. THERE WAS NO MEL LISTED ON THE RELEASE AND NO LIDS ENTRY IN THE LOGBOOK. THE STICKER IN THE FRONT OF THE LOGBOOK STATED: 'AUTOTHROTTLE USE IN APCH MODE ONLY' BUT THERE WAS NO MEL NOTED ON THE STICKER. WE ASKED HKG MAINT ABOUT THIS AND THEY CAME BACK - TOOK THE STICKERS OFF AND SAID THERE WAS NO PROB -- THEY SAID THAT AN EARLIER PROB WITH THROTTLES HAD BEEN SIGNED OFF ON SEP/THU/04, WHICH WE NOTED IN PREVIOUS LOG PAGES. ALSO NOTE THAT THERE HAD BEEN A PREVIOUS INCIDENT OF THE #1 ENG NOT RESPONDING TO THRUST LEVER MOVEMENT AFTER A DSCNT.

Data retrieved from NASA's ASRS site as of July 2007 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.