Narrative:

After takeoff we encountered turbulence which was of sufficient force and duration as to cause the #3 hydraulic elevator off light to illuminate momentarily. This happened as we were approaching 8000 ft. Thunderstorms, virga and windshear were present in the den area at the time. A momentary 300 ft overshoot resulted. We corrected the overshoot and returned to 8000 ft. Supplemental information from acn 246845: our initial level off of 8000 ft was deviated from by about 250-280 ft (8250-8280) for a period of no more than 3-5 seconds, during which time the flight engineer was telling the captain and myself that the 'hydraulic system 3 elevator off' light on his panel was illuminated. There are many contributing factors to this one brief event. The crew: we were nearing the end of a long 3-DAY trip sequence and at this point had been on continuous duty about 9 1/2 hours with about 5 hours of flight time at this point, with 3 time zone changes. We had been deviating constantly around severe thunderstorms for the entire 3 days and when we arrived in the den terminal area on the leg before this one, there were many severe thunderstorms, virga, wet and dry micro/downbursts and all the 'classic' windshear/turbulence phenomena all over the terminal area. We had some heavy turbulence coupled with an actual windshear event on our approach to denver. The aircraft, a widebody transport, normally used for international operations but restr from them for MEL reasons (2 generator operation, 1 main wheel brake deactivated, etc) and a small list of minor and legal malfunctions. With a main wheel brake inoperative we were required by the MEL to not retract the gear until 30 seconds after liftoff, which adds to the workload and distraction on initial climb out. This aircraft with a light load and a short domestic leg also has very good climb performance, which probably helped us greatly during the previous windshear encounter. This excellent climb performance coupled with the quick leveloff necessary on departure, and the resulting high rate demand on the hydraulic system, less than 1 'G' level off, may have caused this system to falsely sense a decrease in the fluid level/leak in the elevator system 3 lines and cause the elevator shutoff valve to close and the light to come on. It was just during this 3-5 second period of aggressive forward 'push' on the yoke that this occurred. This is a prime example of a complex mix of factors that leads to abnormal performance. Human factors: 1) growing crew fatigue. 2) the 'dulling effect' that occurs after taxiing in line for takeoff (a relatively simple process, followed by a complex one) for just under 1 full hour. 3) the 'after the big event effect' of relaxation or overconfidence that occurs after an adrenaline producing occurrence such as actual strong windshear in a heavy jet. 4) the complication from MEL items effecting normal procedures. 5) the possible incorrect function of a system component designed into that system for another purpose but that may have erroneously actuated and reduced elevator effectiveness at a critical time. 6) the severe WX in one of the worse areas in the nation for it which is aggravated by high altitude, mountain waves and turbulence, in very busy airspace.

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Original NASA ASRS Text

Title: FLC OF WDB ACR ACFT OVERSHOT CLB ALT DUE TO FLC DISTR ACFT EQUIP PROB TASK.

Narrative: AFTER TKOF WE ENCOUNTERED TURB WHICH WAS OF SUFFICIENT FORCE AND DURATION AS TO CAUSE THE #3 HYD ELEVATOR OFF LIGHT TO ILLUMINATE MOMENTARILY. THIS HAPPENED AS WE WERE APCHING 8000 FT. TSTMS, VIRGA AND WINDSHEAR WERE PRESENT IN THE DEN AREA AT THE TIME. A MOMENTARY 300 FT OVERSHOOT RESULTED. WE CORRECTED THE OVERSHOOT AND RETURNED TO 8000 FT. SUPPLEMENTAL INFO FROM ACN 246845: OUR INITIAL LEVEL OFF OF 8000 FT WAS DEVIATED FROM BY ABOUT 250-280 FT (8250-8280) FOR A PERIOD OF NO MORE THAN 3-5 SECONDS, DURING WHICH TIME THE FE WAS TELLING THE CAPT AND MYSELF THAT THE 'HYD SYS 3 ELEVATOR OFF' LIGHT ON HIS PANEL WAS ILLUMINATED. THERE ARE MANY CONTRIBUTING FACTORS TO THIS ONE BRIEF EVENT. THE CREW: WE WERE NEARING THE END OF A LONG 3-DAY TRIP SEQUENCE AND AT THIS POINT HAD BEEN ON CONTINUOUS DUTY ABOUT 9 1/2 HRS WITH ABOUT 5 HRS OF FLT TIME AT THIS POINT, WITH 3 TIME ZONE CHANGES. WE HAD BEEN DEVIATING CONSTANTLY AROUND SEVERE TSTMS FOR THE ENTIRE 3 DAYS AND WHEN WE ARRIVED IN THE DEN TERMINAL AREA ON THE LEG BEFORE THIS ONE, THERE WERE MANY SEVERE TSTMS, VIRGA, WET AND DRY MICRO/DOWNBURSTS AND ALL THE 'CLASSIC' WINDSHEAR/TURB PHENOMENA ALL OVER THE TERMINAL AREA. WE HAD SOME HVY TURB COUPLED WITH AN ACTUAL WINDSHEAR EVENT ON OUR APCH TO DENVER. THE ACFT, A WDB, NORMALLY USED FOR INTL OPS BUT RESTR FROM THEM FOR MEL REASONS (2 GENERATOR OP, 1 MAIN WHEEL BRAKE DEACTIVATED, ETC) AND A SMALL LIST OF MINOR AND LEGAL MALFUNCTIONS. WITH A MAIN WHEEL BRAKE INOP WE WERE REQUIRED BY THE MEL TO NOT RETRACT THE GEAR UNTIL 30 SECONDS AFTER LIFTOFF, WHICH ADDS TO THE WORKLOAD AND DISTR ON INITIAL CLBOUT. THIS ACFT WITH A LIGHT LOAD AND A SHORT DOMESTIC LEG ALSO HAS VERY GOOD CLB PERFORMANCE, WHICH PROBABLY HELPED US GREATLY DURING THE PREVIOUS WINDSHEAR ENCOUNTER. THIS EXCELLENT CLB PERFORMANCE COUPLED WITH THE QUICK LEVELOFF NECESSARY ON DEP, AND THE RESULTING HIGH RATE DEMAND ON THE HYD SYS, LESS THAN 1 'G' LEVEL OFF, MAY HAVE CAUSED THIS SYS TO FALSELY SENSE A DECREASE IN THE FLUID LEVEL/LEAK IN THE ELEVATOR SYS 3 LINES AND CAUSE THE ELEVATOR SHUTOFF VALVE TO CLOSE AND THE LIGHT TO COME ON. IT WAS JUST DURING THIS 3-5 SECOND PERIOD OF AGGRESSIVE FORWARD 'PUSH' ON THE YOKE THAT THIS OCCURRED. THIS IS A PRIME EXAMPLE OF A COMPLEX MIX OF FACTORS THAT LEADS TO ABNORMAL PERFORMANCE. HUMAN FACTORS: 1) GROWING CREW FATIGUE. 2) THE 'DULLING EFFECT' THAT OCCURS AFTER TAXIING IN LINE FOR TKOF (A RELATIVELY SIMPLE PROCESS, FOLLOWED BY A COMPLEX ONE) FOR JUST UNDER 1 FULL HR. 3) THE 'AFTER THE BIG EVENT EFFECT' OF RELAXATION OR OVERCONFIDENCE THAT OCCURS AFTER AN ADRENALINE PRODUCING OCCURRENCE SUCH AS ACTUAL STRONG WINDSHEAR IN A HVY JET. 4) THE COMPLICATION FROM MEL ITEMS EFFECTING NORMAL PROCS. 5) THE POSSIBLE INCORRECT FUNCTION OF A SYS COMPONENT DESIGNED INTO THAT SYS FOR ANOTHER PURPOSE BUT THAT MAY HAVE ERRONEOUSLY ACTUATED AND REDUCED ELEVATOR EFFECTIVENESS AT A CRITICAL TIME. 6) THE SEVERE WX IN ONE OF THE WORSE AREAS IN THE NATION FOR IT WHICH IS AGGRAVATED BY HIGH ALT, MOUNTAIN WAVES AND TURB, IN VERY BUSY AIRSPACE.

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.