Narrative:

While descending from FL430 to FL410, I retarded the power levers to reduce airspeed. At approximately FL425 the right engine reversed command of my input and headed towards an overspd trend. I shut off the engine using the power lever idle/cutoff detent and the problem was resolved. Told ZMA immediately after shutdown that we had to shut down the right engine and needed to descend to FL250 in order to maintain an altitude which provides safe single engine operation speed as well as an altitude which is warmer and capable of air start. At FL250 we encountered clouds and icing so we immediately got approval for FL210 which was VMC. We were able to start the right engine but showed another trend towards uncontrollable power lever inputs. By now we were 100 NM from our destination which was ZZZ. Decided we would fly single engine to ZZZ where I had our dispatcher set up customs. We were coming from ZZZ1, did all appropriate checklists, and rehearsed procedures for other emergency occurrences which could happen while flying single engine. I never actually declared an emergency but ZMA knew our situation after shutdown and let us continue descending. Landed uneventfully and found out that a fuel computer probe must have had moisture in it before we took off and froze at the high altitude which confused the fuel computer. Was cleaned out and has been flying fine since the incident.

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Original NASA ASRS Text

Title: LJ35 CREW HAD A RUNAWAY ENG THAT REQUIRED AN INFLT ENG SHUTDOWN IN CARIBBEAN EXTENDED OVERWATER OP.

Narrative: WHILE DSNDING FROM FL430 TO FL410, I RETARDED THE PWR LEVERS TO REDUCE AIRSPD. AT APPROX FL425 THE R ENG REVERSED COMMAND OF MY INPUT AND HEADED TOWARDS AN OVERSPD TREND. I SHUT OFF THE ENG USING THE PWR LEVER IDLE/CUTOFF DETENT AND THE PROB WAS RESOLVED. TOLD ZMA IMMEDIATELY AFTER SHUTDOWN THAT WE HAD TO SHUT DOWN THE R ENG AND NEEDED TO DSND TO FL250 IN ORDER TO MAINTAIN AN ALT WHICH PROVIDES SAFE SINGLE ENG OP SPD AS WELL AS AN ALT WHICH IS WARMER AND CAPABLE OF AIR START. AT FL250 WE ENCOUNTERED CLOUDS AND ICING SO WE IMMEDIATELY GOT APPROVAL FOR FL210 WHICH WAS VMC. WE WERE ABLE TO START THE R ENG BUT SHOWED ANOTHER TREND TOWARDS UNCTLABLE PWR LEVER INPUTS. BY NOW WE WERE 100 NM FROM OUR DEST WHICH WAS ZZZ. DECIDED WE WOULD FLY SINGLE ENG TO ZZZ WHERE I HAD OUR DISPATCHER SET UP CUSTOMS. WE WERE COMING FROM ZZZ1, DID ALL APPROPRIATE CHKLISTS, AND REHEARSED PROCS FOR OTHER EMER OCCURRENCES WHICH COULD HAPPEN WHILE FLYING SINGLE ENG. I NEVER ACTUALLY DECLARED AN EMER BUT ZMA KNEW OUR SIT AFTER SHUTDOWN AND LET US CONTINUE DSNDING. LANDED UNEVENTFULLY AND FOUND OUT THAT A FUEL COMPUTER PROBE MUST HAVE HAD MOISTURE IN IT BEFORE WE TOOK OFF AND FROZE AT THE HIGH ALT WHICH CONFUSED THE FUEL COMPUTER. WAS CLEANED OUT AND HAS BEEN FLYING FINE SINCE THE INCIDENT.

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.