<< >> NASA ASRS Report 474277, May 2000

A B777-200 parked in a hangar incurred a large fuel spill when replacing a left main tank forward boost pump caused by the pump cavity check valve failure.

Attributes
ACN	474277
Time
Date	200005
Day	Sat
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B777-200
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : airframe technician : powerplant
Experience	maintenance technician : 10
ASRS Report	474277
Person 2
Affiliation	company : air carrier
Function	maintenance : lead technician
Qualification	technician : powerplant technician : airframe
Experience	maintenance lead technician : 8 maintenance technician : 7
ASRS Report	473778
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other other : person 1
Consequence	other other
Factors
Maintenance	performance deficiency : installation performance deficiency : repair performance deficiency : scheduled maintenance
Supplementary
Problem Areas	Maintenance Human Performance Aircraft Chart Or Publication
Primary Problem	Aircraft

Narrative:

Assigned change order authority/authorized -- followed steps 1,2, 3, and 4. After removing valve, fuel spill occurred. Fuel was xferred from l-hand tank to r-hand tank until l-hand tank read zero, then removal process continued. End result was a fuel spill. No aircraft damage occurred. No fuel entered drain system. Fuel was cleaned up without incident. I believe the cause was unwanted fuel xfer back to l-hand tank or bad fuel gauge reading.

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Original NASA ASRS Text

Title: A B777-200 PARKED IN A HANGAR INCURRED A LARGE FUEL SPILL WHEN REPLACING A L MAIN TANK FORWARD BOOST PUMP CAUSED BY THE PUMP CAVITY CHK VALVE FAILURE.

Narrative: ASSIGNED CHANGE ORDER AUTH -- FOLLOWED STEPS 1,2, 3, AND 4. AFTER REMOVING VALVE, FUEL SPILL OCCURRED. FUEL WAS XFERRED FROM L-HAND TANK TO R-HAND TANK UNTIL L-HAND TANK READ ZERO, THEN REMOVAL PROCESS CONTINUED. END RESULT WAS A FUEL SPILL. NO ACFT DAMAGE OCCURRED. NO FUEL ENTERED DRAIN SYS. FUEL WAS CLEANED UP WITHOUT INCIDENT. I BELIEVE THE CAUSE WAS UNWANTED FUEL XFER BACK TO L-HAND TANK OR BAD FUEL GAUGE READING.

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.