Narrative:

Flight was cruising in smooth air at FL430. Approximately 4 mins before event, flight started experiencing moderate to severe chop. Flcs asked and obtained ride reports in the vicinity. Aircraft directly ahead 15 mi was reporting it. Flight crew asked for FL450, received it after some delay -- possibly 3 mins. Just prior to the start of the chop a wind readout was requested for and received from an aircraft 60 NM north of our position winds 250 degrees at 52 KTS, ahead by 10 mi 290 degrees at 42 KTS, and our winds were 330 degrees at 15 KTS. Climb to FL450 was commenced, on autoplt, power increased to climb EPR and 1000 FPM rate was established. At FL442 chop ceased and climb continued. Upon reaching FL449 rate of climb was increasing. Leveloff was attempted with autoplt with no success. At FL454, autoplt was selected off and leveloff was attempted. Any attempt to level aircraft or at least return to FL450 was initially unsuccessful. Power by now was back to soft stops and trim was attempted. As nose down trim was selected, it appeared that electric trim was either jammed or responding erratically. Manual trim was selected but autoplt trim continued to now pitch aircraft into 1500 FPM descent. We immediately requested and received a block altitude of F450-FL430. Crew began emergency procedure checklist for erratic or failed electric trim. Aircraft was continuing an uncontrolled descent of between 1000-2500 FPM. Control surfaces seemed extremely heavy with an accompanied slight vibration in control yoke. Airspeed excursion of 50 KTS were occurring and power levers were used twice to attempt to level aircraft. While passing through FL390 crew requested and received a northbound turn to rap, suggesting to the controller that they were heading to rap in the event the trim problem could not be fixed. All along during these climbs and dscnts crew was trying to evaluate the possibilities of either electric trim or autoplt servos not disconnecting. At FL370, control of aircraft was regained, although manual trim was the only one being used, autoplt was off. Crew continued to FL330 and determined that problem had gone away. Following electric trim inoperative checklist crew continued flight to vny with no further incident. FL310 was used for remainder of trip. Contributing factors: crew surprised by unexpected turbulence. Most flight experience was in G3 with different autoplt and trim system. Human factors considerations: in the previous 48 hours crew had had periods of interrupted rest. Perceptions: I felt that the initial problem was a trim problem, the decision to attempt to hand fly the aircraft may have resulted in overctling. Not until later that evening after the flight was concluded had I thought of the possibility of entering an extremely downward pushing mountain wave. Although with this thought in mind, none of the other aircraft in our vicinity were reporting it. The aircraft was finally brought under control by a continued and vigilant crew effort. The flight attendant was kept informed to the best of our ability. After the incident was over I went into the cabin and explained the situation to the passenger. Callback conversation with reporter revealed the following information: reporter indicated that maintenance did a thorough check of the aircraft upon arrival and no discrepancies were found with the trim or autoplt system. Aircraft has been flown more than 20 hours since with no incidents or malfunctions. This aircraft has the winglet modification. He is not sure if this is a factor. Pilot said that the turbulence encountered could have been associated with their location on the north side of a jetstream. It was indicated that the altitude was well within the operating envelope of the aircraft. Reporter indicated that he now feels that he was probably over controling the aircraft once he reverted to manual control and that the vibration he felt was probably caused by approaching the high speed mach limit.

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Original NASA ASRS Text

Title: G2 PLT CLBS TO FL450 TO AVOID TURB BUT IS UNABLE TO LEVEL AT ALT USING AUTOPLT. UNABLE TO MAINTAIN ALT, A BLOCK ALT WAS RECEIVED FROM ARTCC. USING MANUAL FLT AND TRIM PROCS, RECOVERY WAS MADE AND FLT COMPLETED AT FL310.

Narrative: FLT WAS CRUISING IN SMOOTH AIR AT FL430. APPROX 4 MINS BEFORE EVENT, FLT STARTED EXPERIENCING MODERATE TO SEVERE CHOP. FLCS ASKED AND OBTAINED RIDE RPTS IN THE VICINITY. ACFT DIRECTLY AHEAD 15 MI WAS RPTING IT. FLC ASKED FOR FL450, RECEIVED IT AFTER SOME DELAY -- POSSIBLY 3 MINS. JUST PRIOR TO THE START OF THE CHOP A WIND READOUT WAS REQUESTED FOR AND RECEIVED FROM AN ACFT 60 NM N OF OUR POS WINDS 250 DEGS AT 52 KTS, AHEAD BY 10 MI 290 DEGS AT 42 KTS, AND OUR WINDS WERE 330 DEGS AT 15 KTS. CLB TO FL450 WAS COMMENCED, ON AUTOPLT, PWR INCREASED TO CLB EPR AND 1000 FPM RATE WAS ESTABLISHED. AT FL442 CHOP CEASED AND CLB CONTINUED. UPON REACHING FL449 RATE OF CLB WAS INCREASING. LEVELOFF WAS ATTEMPTED WITH AUTOPLT WITH NO SUCCESS. AT FL454, AUTOPLT WAS SELECTED OFF AND LEVELOFF WAS ATTEMPTED. ANY ATTEMPT TO LEVEL ACFT OR AT LEAST RETURN TO FL450 WAS INITIALLY UNSUCCESSFUL. PWR BY NOW WAS BACK TO SOFT STOPS AND TRIM WAS ATTEMPTED. AS NOSE DOWN TRIM WAS SELECTED, IT APPEARED THAT ELECTRIC TRIM WAS EITHER JAMMED OR RESPONDING ERRATICALLY. MANUAL TRIM WAS SELECTED BUT AUTOPLT TRIM CONTINUED TO NOW PITCH ACFT INTO 1500 FPM DSCNT. WE IMMEDIATELY REQUESTED AND RECEIVED A BLOCK ALT OF F450-FL430. CREW BEGAN EMER PROC CHKLIST FOR ERRATIC OR FAILED ELECTRIC TRIM. ACFT WAS CONTINUING AN UNCTLED DSCNT OF BTWN 1000-2500 FPM. CTL SURFACES SEEMED EXTREMELY HVY WITH AN ACCOMPANIED SLIGHT VIBRATION IN CTL YOKE. AIRSPD EXCURSION OF 50 KTS WERE OCCURRING AND PWR LEVERS WERE USED TWICE TO ATTEMPT TO LEVEL ACFT. WHILE PASSING THROUGH FL390 CREW REQUESTED AND RECEIVED A NBOUND TURN TO RAP, SUGGESTING TO THE CTLR THAT THEY WERE HDG TO RAP IN THE EVENT THE TRIM PROB COULD NOT BE FIXED. ALL ALONG DURING THESE CLBS AND DSCNTS CREW WAS TRYING TO EVALUATE THE POSSIBILITIES OF EITHER ELECTRIC TRIM OR AUTOPLT SERVOS NOT DISCONNECTING. AT FL370, CTL OF ACFT WAS REGAINED, ALTHOUGH MANUAL TRIM WAS THE ONLY ONE BEING USED, AUTOPLT WAS OFF. CREW CONTINUED TO FL330 AND DETERMINED THAT PROB HAD GONE AWAY. FOLLOWING ELECTRIC TRIM INOP CHKLIST CREW CONTINUED FLT TO VNY WITH NO FURTHER INCIDENT. FL310 WAS USED FOR REMAINDER OF TRIP. CONTRIBUTING FACTORS: CREW SURPRISED BY UNEXPECTED TURB. MOST FLT EXPERIENCE WAS IN G3 WITH DIFFERENT AUTOPLT AND TRIM SYS. HUMAN FACTORS CONSIDERATIONS: IN THE PREVIOUS 48 HRS CREW HAD HAD PERIODS OF INTERRUPTED REST. PERCEPTIONS: I FELT THAT THE INITIAL PROB WAS A TRIM PROB, THE DECISION TO ATTEMPT TO HAND FLY THE ACFT MAY HAVE RESULTED IN OVERCTLING. NOT UNTIL LATER THAT EVENING AFTER THE FLT WAS CONCLUDED HAD I THOUGHT OF THE POSSIBILITY OF ENTERING AN EXTREMELY DOWNWARD PUSHING MOUNTAIN WAVE. ALTHOUGH WITH THIS THOUGHT IN MIND, NONE OF THE OTHER ACFT IN OUR VICINITY WERE RPTING IT. THE ACFT WAS FINALLY BROUGHT UNDER CTL BY A CONTINUED AND VIGILANT CREW EFFORT. THE FLT ATTENDANT WAS KEPT INFORMED TO THE BEST OF OUR ABILITY. AFTER THE INCIDENT WAS OVER I WENT INTO THE CABIN AND EXPLAINED THE SIT TO THE PAX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT MAINT DID A THOROUGH CHK OF THE ACFT UPON ARR AND NO DISCREPANCIES WERE FOUND WITH THE TRIM OR AUTOPLT SYS. ACFT HAS BEEN FLOWN MORE THAN 20 HRS SINCE WITH NO INCIDENTS OR MALFUNCTIONS. THIS ACFT HAS THE WINGLET MODIFICATION. HE IS NOT SURE IF THIS IS A FACTOR. PLT SAID THAT THE TURB ENCOUNTERED COULD HAVE BEEN ASSOCIATED WITH THEIR LOCATION ON THE N SIDE OF A JETSTREAM. IT WAS INDICATED THAT THE ALT WAS WELL WITHIN THE OPERATING ENVELOPE OF THE ACFT. RPTR INDICATED THAT HE NOW FEELS THAT HE WAS PROBABLY OVER CTLING THE ACFT ONCE HE REVERTED TO MANUAL CTL AND THAT THE VIBRATION HE FELT WAS PROBABLY CAUSED BY APCHING THE HIGH SPD MACH LIMIT.

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.