|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||airport : zzz.airport|
|Altitude||msl single value : 17000|
|Controlling Facilities||tower : zzz.tower|
|Operator||common carrier : air carrier|
|Make Model Name||SF 340B|
|Operating Under FAR Part||Part 121|
|Flight Phase||cruise : level|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
observation : company check pilot
oversight : pic
|Qualification||pilot : atp|
|Anomaly||aircraft equipment problem : critical|
|Independent Detector||other flight crewa|
|Resolutory Action||aircraft : equipment problem dissipated|
|Maintenance||contributing factor : weather|
performance deficiency : scheduled maintenance
|Problem Areas||Maintenance Human Performance|
|Primary Problem||Maintenance Human Performance|
When ATC gave us a descent from our cruise altitude of 17000 ft; I was unable to reduce power on the right engine from our cruise power setting of 75 percent. The power lever was frozen (I believe literally frozen) in position. As we descended to 11000 ft; using as much force as I dared for fear of snapping something and making matters worse; I was able to reduce power slightly. Over the next 10-15 minutes I was able to restore full power lever travel and engine control. We advised ATC and had arff waiting at the field. Landing was normal. Maintenance sent mechanics to repair the plane. We were told the next morning that a power lever cable was replaced and they felt confident that it was fixed. The next morning we deadheaded the plane to ZZZ1 and the exact problem reoccurred at 16000 ft and -16C. We descended to 8000 ft and again the problem cleared. I have heard that the plane was being worked on during heavy continuous rain in ZZZ1. It's not hard to figure out that moisture could get into the system. How about a hangar for ZZZ1?!callback conversation with reporter revealed the following information: reporter stated the problem with the engine throttle literally 'freezing-up' seemed to have appeared earlier; when the previous flight crew found their right engine throttle locked in position at cruise. This crew could not get the power lever 'unfrozen' and had to shut down the engine in-flight. Reporter stated there are three throttle cables for each engine. Maintenance changed one of the three throttle cables after the first incident. Reporter then flew the same aircraft on his first leg and encountered the same 'freezing-up' of the right engine power lever while at cruise and 75% power setting. After descending to 11000 ft; he was eventually able to restore full power lever travel and engine control. The next morning; reporter was told by maintenance that a second throttle cable was found frayed and replaced. Reporter stated he then departed on a deadhead route to a different station flying the same aircraft. However; en route; the exact same problem re-occurred at 16000 ft. They descended to 8000 ft and the problem cleared. Reporter noted that maintenance replaced the third throttle cable; but this time; maintenance also found moisture pooling in the wing to engine nacelle area where the throttle cables are routed from the throttle quadrant to the engine. Approximately three to four tablespoons of water were removed from this area.
Original NASA ASRS Text
Title: A SAAB 340B CHECK PILOT REPORTS HE IS UNABLE TO REDUCE POWER ON RIGHT ENG FROM CRUISE POWER SETTING OF 75% UNTIL DESCENT TO 11;000 FT. POWER LEVER WAS FROZEN IN POSITION. MOISTURE FREEZING AT ALTITUDE SUSPECTED.
Narrative: WHEN ATC GAVE US A DESCENT FROM OUR CRUISE ALTITUDE OF 17000 FT; I WAS UNABLE TO REDUCE POWER ON THE RIGHT ENGINE FROM OUR CRUISE POWER SETTING OF 75 PERCENT. THE POWER LEVER WAS FROZEN (I BELIEVE LITERALLY FROZEN) IN POSITION. AS WE DESCENDED TO 11000 FT; USING AS MUCH FORCE AS I DARED FOR FEAR OF SNAPPING SOMETHING AND MAKING MATTERS WORSE; I WAS ABLE TO REDUCE POWER SLIGHTLY. OVER THE NEXT 10-15 MINUTES I WAS ABLE TO RESTORE FULL POWER LEVER TRAVEL AND ENGINE CONTROL. WE ADVISED ATC AND HAD ARFF WAITING AT THE FIELD. LANDING WAS NORMAL. MAINT SENT MECHANICS TO REPAIR THE PLANE. WE WERE TOLD THE NEXT MORNING THAT A POWER LEVER CABLE WAS REPLACED AND THEY FELT CONFIDENT THAT IT WAS FIXED. THE NEXT MORNING WE DEADHEADED THE PLANE TO ZZZ1 AND THE EXACT PROBLEM REOCCURRED AT 16000 FT AND -16C. WE DESCENDED TO 8000 FT AND AGAIN THE PROBLEM CLEARED. I HAVE HEARD THAT THE PLANE WAS BEING WORKED ON DURING HEAVY CONTINUOUS RAIN IN ZZZ1. IT'S NOT HARD TO FIGURE OUT THAT MOISTURE COULD GET INTO THE SYSTEM. HOW ABOUT A HANGAR FOR ZZZ1?!CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE PROBLEM WITH THE ENGINE THROTTLE LITERALLY 'FREEZING-UP' SEEMED TO HAVE APPEARED EARLIER; WHEN THE PREVIOUS FLIGHT CREW FOUND THEIR RIGHT ENG THROTTLE LOCKED IN POSITION AT CRUISE. THIS CREW COULD NOT GET THE POWER LEVER 'UNFROZEN' AND HAD TO SHUT DOWN THE ENGINE IN-FLIGHT. REPORTER STATED THERE ARE THREE THROTTLE CABLES FOR EACH ENGINE. MAINT CHANGED ONE OF THE THREE THROTTLE CABLES AFTER THE FIRST INCIDENT. REPORTER THEN FLEW THE SAME ACFT ON HIS FIRST LEG AND ENCOUNTERED THE SAME 'FREEZING-UP' OF THE RIGHT ENGINE POWER LEVER WHILE AT CRUISE AND 75% POWER SETTING. AFTER DESCENDING TO 11000 FT; HE WAS EVENTUALLY ABLE TO RESTORE FULL POWER LEVER TRAVEL AND ENGINE CONTROL. THE NEXT MORNING; REPORTER WAS TOLD BY MAINT THAT A SECOND THROTTLE CABLE WAS FOUND FRAYED AND REPLACED. REPORTER STATED HE THEN DEPARTED ON A DEADHEAD ROUTE TO A DIFFERENT STATION FLYING THE SAME ACFT. HOWEVER; ENRTE; THE EXACT SAME PROBLEM RE-OCCURRED AT 16000 FT. THEY DESCENDED TO 8000 FT AND THE PROBLEM CLEARED. REPORTER NOTED THAT MAINT REPLACED THE THIRD THROTTLE CABLE; BUT THIS TIME; MAINT ALSO FOUND MOISTURE POOLING IN THE WING TO ENGINE NACELLE AREA WHERE THE THROTTLE CABLES ARE ROUTED FROM THE THROTTLE QUADRANT TO THE ENGINE. APPROX THREE TO FOUR TABLESPOONS OF WATER WERE REMOVED FROM THIS AREA.
Data retrieved from NASA's ASRS site as of May 2009 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.