Narrative:

Narrative from acn #797762: on jul/xa/08 the flight started in ZZZ with a destination of ZZZ. The purpose of the flight was to take a medical team to ZZZ and drop them off so they could harvest a heart and a liver. Our departure time out of ZZZ was XA30. It was a clear VFR day and the flight was normal until about 12000 ft when the primary yaw damper jerked the tail around a little as if it kicked off; so we switched to the secondary. I hand flew the aircraft up to about 14000 ft; at which time I turned on the autoplt and was flying in navigation mode. We leveled off at FL240 and I noticed that the aircraft did not want to hold a course and had a right rolling tendency; so my first officer suggested that I fly it in heading mode to see if it did any better. Flying in heading mode helped to level the wings and hold a course for a few mins. I noticed again that the aircraft was not holding a heading and was still trying to roll to the right. At this point we got a master caution with a low fuel light; so we went to the fuel panel to see what was going on. We noticed that we had an imbal in the right wing of about 400 pounds less than the left wing (left wing had 1100 pounds and right wing had 700 pounds); so we tried to xfer out of the left wing to even the load but the fuel did not seem to want to xfer. At the same time we noticed that we had burned almost 1000 pounds in 20 mins; and that we had burned all the fuel in the left tip; but still had 150 pounds in the right tip. We visually checked the tips to see if we were losing fuel at the caps; but could not see any leaks. The fuel in the right tip was causing the right rolling tendency and was becoming hard to control; so asked for priority handling and declared an emergency. The controller turned us towards ZZZ and gave us a descent. During the descent the aircraft was still taking a lot of left input to hold the wings level. We saw what we thought was ZZZ and lined up on final; but it turned out to be ZZZ; asked for landing clearance; and we landed without any further problems. When we shut the aircraft down we had zero fuel in the left tip; 800-850 pounds in the left wing; 600 pounds in the right wing and 150 pounds in the right tip. When we got out and did a walkaround; everything was normal except that the right engine had a strong smell of fuel as if it was running excessively rich. We first believed that the aircraft had a jet pump failure in the right tip which left fuel in the right tip tank causing the imbal and aircraft control problems. Our director of operations and director of maintenance flew over to help diagnose the problem and after refueling the aircraft we found that we actually had a flapper valve in the right tip tank that had failed. The problem was purely mechanical and there was really nothing that could have been done to prevent this from happening. All of the controllers did a great job in handling our situation. They gave us exactly what we needed with no questions asked and helped us to find a safe place to land.

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Original NASA ASRS Text

Title: LEAR 35 FLT CREW REPORTS YAW DAMPER AND FUEL BALANCE PROBLEMS AT FL240 AND DIVERT TO NEAREST SUITABLE ARPT.

Narrative: NARRATIVE FROM ACN #797762: ON JUL/XA/08 THE FLT STARTED IN ZZZ WITH A DEST OF ZZZ. THE PURPOSE OF THE FLT WAS TO TAKE A MEDICAL TEAM TO ZZZ AND DROP THEM OFF SO THEY COULD HARVEST A HEART AND A LIVER. OUR DEP TIME OUT OF ZZZ WAS XA30. IT WAS A CLR VFR DAY AND THE FLT WAS NORMAL UNTIL ABOUT 12000 FT WHEN THE PRIMARY YAW DAMPER JERKED THE TAIL AROUND A LITTLE AS IF IT KICKED OFF; SO WE SWITCHED TO THE SECONDARY. I HAND FLEW THE ACFT UP TO ABOUT 14000 FT; AT WHICH TIME I TURNED ON THE AUTOPLT AND WAS FLYING IN NAV MODE. WE LEVELED OFF AT FL240 AND I NOTICED THAT THE ACFT DID NOT WANT TO HOLD A COURSE AND HAD A R ROLLING TENDENCY; SO MY FO SUGGESTED THAT I FLY IT IN HDG MODE TO SEE IF IT DID ANY BETTER. FLYING IN HDG MODE HELPED TO LEVEL THE WINGS AND HOLD A COURSE FOR A FEW MINS. I NOTICED AGAIN THAT THE ACFT WAS NOT HOLDING A HDG AND WAS STILL TRYING TO ROLL TO THE R. AT THIS POINT WE GOT A MASTER CAUTION WITH A LOW FUEL LIGHT; SO WE WENT TO THE FUEL PANEL TO SEE WHAT WAS GOING ON. WE NOTICED THAT WE HAD AN IMBAL IN THE R WING OF ABOUT 400 LBS LESS THAN THE L WING (L WING HAD 1100 LBS AND R WING HAD 700 LBS); SO WE TRIED TO XFER OUT OF THE L WING TO EVEN THE LOAD BUT THE FUEL DID NOT SEEM TO WANT TO XFER. AT THE SAME TIME WE NOTICED THAT WE HAD BURNED ALMOST 1000 LBS IN 20 MINS; AND THAT WE HAD BURNED ALL THE FUEL IN THE L TIP; BUT STILL HAD 150 LBS IN THE R TIP. WE VISUALLY CHKED THE TIPS TO SEE IF WE WERE LOSING FUEL AT THE CAPS; BUT COULD NOT SEE ANY LEAKS. THE FUEL IN THE R TIP WAS CAUSING THE R ROLLING TENDENCY AND WAS BECOMING HARD TO CTL; SO ASKED FOR PRIORITY HANDLING AND DECLARED AN EMER. THE CTLR TURNED US TOWARDS ZZZ AND GAVE US A DSCNT. DURING THE DSCNT THE ACFT WAS STILL TAKING A LOT OF L INPUT TO HOLD THE WINGS LEVEL. WE SAW WHAT WE THOUGHT WAS ZZZ AND LINED UP ON FINAL; BUT IT TURNED OUT TO BE ZZZ; ASKED FOR LNDG CLRNC; AND WE LANDED WITHOUT ANY FURTHER PROBS. WHEN WE SHUT THE ACFT DOWN WE HAD ZERO FUEL IN THE L TIP; 800-850 LBS IN THE L WING; 600 LBS IN THE R WING AND 150 LBS IN THE R TIP. WHEN WE GOT OUT AND DID A WALKAROUND; EVERYTHING WAS NORMAL EXCEPT THAT THE R ENG HAD A STRONG SMELL OF FUEL AS IF IT WAS RUNNING EXCESSIVELY RICH. WE FIRST BELIEVED THAT THE ACFT HAD A JET PUMP FAILURE IN THE R TIP WHICH LEFT FUEL IN THE R TIP TANK CAUSING THE IMBAL AND ACFT CTL PROBS. OUR DIRECTOR OF OPS AND DIRECTOR OF MAINT FLEW OVER TO HELP DIAGNOSE THE PROB AND AFTER REFUELING THE ACFT WE FOUND THAT WE ACTUALLY HAD A FLAPPER VALVE IN THE R TIP TANK THAT HAD FAILED. THE PROB WAS PURELY MECHANICAL AND THERE WAS REALLY NOTHING THAT COULD HAVE BEEN DONE TO PREVENT THIS FROM HAPPENING. ALL OF THE CTLRS DID A GREAT JOB IN HANDLING OUR SITUATION. THEY GAVE US EXACTLY WHAT WE NEEDED WITH NO QUESTIONS ASKED AND HELPED US TO FIND A SAFE PLACE TO LAND.

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.