Pilot reports a B737-800 had two previous write ups of fuel transferring past the crossfeed valve in...

Attributes
ACN	806875
Time
Date	200810
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Light	Night
Aircraft 1
Controlling Facilities	tower : zzz.tower
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	806875
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : published procedure non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	performance deficiency : repair performance deficiency : testing performance deficiency : non compliance with legal requirements performance deficiency : logbook entry
Supplementary
Problem Areas	Maintenance Human Performance Aircraft Company
Primary Problem	Maintenance Human Performance

Narrative:

Aircraft had 2 previous write-ups of fuel xferring past the xfeed valve in-flight leading to an imbalanced condition between main (wing) tanks. Closest maintenance deferred items code used to describe problem was for slow or sticking xfeed valve although all write-ups of problem were very specific that it was a xflow problem with the valve indicating closed; not a valve speed problem. I repeated the write-up as the problem still existed and requested maintenance meet the aircraft on arrival so as to explain the problem in exacting detail face-to-face. Maintenance met the aircraft and related that he had already been in contact with maintenance control and that they recognized the true culprit was the xfeed valve. In that 'they' did not have a valve to change out; 'they' were going to change the 2 tank boost pumps on the heavy side so as to balance the pressures between the tanks; thus mitigating the xfer until the xfeed valve could be changed at some time in the uncertain future. The aircraft had a known history with several attempts to fix it using the same procedure checking for blow-by on the ground. Yet the problem repeated in the air; in actual use conditions. Checking the aircraft maintenance history this morning; I noticed a continuation of the ground check for blow-by that didn't work before and now an apparent deferral of the item number aircraft maintenance history record of a double pump change. So there it is folks. No part available. Problem known to a certainty. Maintenance procedure implemented to the wrong part of the system so as to answer the squawk and keep the aircraft moving until it became convenient to actually fix it. Callback conversation with reporter revealed the following information: reporter stated even with matched fuel consumption; one wing tank was showing noticeable fuel imbalances; even though the crossfeed valve on the B737-800 was indicating closed.

Original NASA ASRS Text

Title: PILOT REPORTS A B737-800 HAD TWO PREVIOUS WRITE UPS OF FUEL TRANSFERRING PAST THE CROSSFEED VALVE INFLIGHT LEADING TO AN IMBALANCED CONDITION BETWEEN MAIN (WING) TANKS.

Narrative: ACFT HAD 2 PREVIOUS WRITE-UPS OF FUEL XFERRING PAST THE XFEED VALVE INFLT LEADING TO AN IMBALANCED CONDITION BTWN MAIN (WING) TANKS. CLOSEST MAINT DEFERRED ITEMS CODE USED TO DESCRIBE PROB WAS FOR SLOW OR STICKING XFEED VALVE ALTHOUGH ALL WRITE-UPS OF PROB WERE VERY SPECIFIC THAT IT WAS A XFLOW PROB WITH THE VALVE INDICATING CLOSED; NOT A VALVE SPD PROB. I REPEATED THE WRITE-UP AS THE PROB STILL EXISTED AND REQUESTED MAINT MEET THE ACFT ON ARR SO AS TO EXPLAIN THE PROB IN EXACTING DETAIL FACE-TO-FACE. MAINT MET THE ACFT AND RELATED THAT HE HAD ALREADY BEEN IN CONTACT WITH MAINT CTL AND THAT THEY RECOGNIZED THE TRUE CULPRIT WAS THE XFEED VALVE. IN THAT 'THEY' DID NOT HAVE A VALVE TO CHANGE OUT; 'THEY' WERE GOING TO CHANGE THE 2 TANK BOOST PUMPS ON THE HVY SIDE SO AS TO BALANCE THE PRESSURES BTWN THE TANKS; THUS MITIGATING THE XFER UNTIL THE XFEED VALVE COULD BE CHANGED AT SOME TIME IN THE UNCERTAIN FUTURE. THE ACFT HAD A KNOWN HISTORY WITH SEVERAL ATTEMPTS TO FIX IT USING THE SAME PROC CHKING FOR BLOW-BY ON THE GND. YET THE PROB REPEATED IN THE AIR; IN ACTUAL USE CONDITIONS. CHKING THE ACFT MAINT HISTORY THIS MORNING; I NOTICED A CONTINUATION OF THE GND CHK FOR BLOW-BY THAT DIDN'T WORK BEFORE AND NOW AN APPARENT DEFERRAL OF THE ITEM NUMBER ACFT MAINT HISTORY RECORD OF A DOUBLE PUMP CHANGE. SO THERE IT IS FOLKS. NO PART AVAILABLE. PROB KNOWN TO A CERTAINTY. MAINT PROC IMPLEMENTED TO THE WRONG PART OF THE SYS SO AS TO ANSWER THE SQUAWK AND KEEP THE ACFT MOVING UNTIL IT BECAME CONVENIENT TO ACTUALLY FIX IT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED EVEN WITH MATCHED FUEL CONSUMPTION; ONE WING TANK WAS SHOWING NOTICEABLE FUEL IMBALANCES; EVEN THOUGH THE CROSSFEED VALVE ON THE B737-800 WAS INDICATING CLOSED.

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.

Pilot reports a B737-800 had two previous write ups of fuel transferring past the crossfeed valve inflight leading to an imbalanced condition between main (wing) tanks.