B737-300 crew diagnosed their own fuel quantity problem, and told the local mechanic what to defer.

Attributes
ACN	586184
Time
Date	200306
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : takeoff roll ground : maintenance
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 17500 flight time type : 14000
ASRS Report	586184
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : non compliance with mel non adherence : company policies non adherence : published procedure non adherence : far
Independent Detector	aircraft equipment other aircraft equipment : fuel quantity indicators, totalizer other flight crewa other flight crewb
Resolutory Action	other
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : non compliance with legal requirements performance deficiency : fault isolation
Supplementary
Problem Areas	Aircraft Maintenance Human Performance Flight Crew Human Performance Company
Primary Problem	Maintenance Human Performance

Narrative:

During preflight there was a 1300 pound difference in the fuel quantity between the fuel gauges and the CDU. (The CDU was reading lower than the gauges). We looked up the associated MEL and determined that the fuel summation unit needed to be deferred. We notified maintenance, and a mechanic came out and concurred that the fuel summation unit needed to be deferred. He communicated with out headquarter maintenance and MEL'ed the fuel summation unit. I checked the logbook, and we proceeded to our destination. When I checked the fuel at level off, I noticed we still had the same quantity of fuel (per the fuel gauges) as we had left with. Upon looking at the circuit breaker panel, I saw that the fuel quantity circuit breaker and one other fuel associated circuit breaker was pulled and collared. After talking with my first officer and a check airman, who was riding jumpseat, we determined that we could reset the circuit breaker, since it had not been tripped. Otherwise, we would have no way of knowing how much fuel we actually had. Upon arrival, we had maintenance come out and correct the problem by installing a new fuel summation unit. Upon talking with the mechanic, I found out that the mechanic, who deferred the fuel summation unit, was pull the circuit breakers, disconnect the fuel summation unit, and then reset the circuit breakers. Later, upon talking with my first officer, I found out that the mechanic, in our originating city had first disconnected the fuel summation unit and then pulled and collared the circuit breakers. I trust our mechanics to do their work correctly, and as a pilot, I do not always have the luxury or knowledge to check that they complete their work correctly. Sometimes I only have the signed off logbook to tell me that all maintenance has been performed correctly. However, in this case, I could have verified that he indeed had pulled and collared the circuit breakers, and if they were to be collared. Seeing the fuel quantity circuit breaker pulled and collared should have raised a red flag before departure.

Original NASA ASRS Text

Title: B737-300 CREW DIAGNOSED THEIR OWN FUEL QUANTITY PROB, AND TOLD THE LCL MECH WHAT TO DEFER.

Narrative: DURING PREFLT THERE WAS A 1300 LB DIFFERENCE IN THE FUEL QUANTITY BTWN THE FUEL GAUGES AND THE CDU. (THE CDU WAS READING LOWER THAN THE GAUGES). WE LOOKED UP THE ASSOCIATED MEL AND DETERMINED THAT THE FUEL SUMMATION UNIT NEEDED TO BE DEFERRED. WE NOTIFIED MAINT, AND A MECH CAME OUT AND CONCURRED THAT THE FUEL SUMMATION UNIT NEEDED TO BE DEFERRED. HE COMMUNICATED WITH OUT HEADQUARTER MAINT AND MEL'ED THE FUEL SUMMATION UNIT. I CHKED THE LOGBOOK, AND WE PROCEEDED TO OUR DEST. WHEN I CHKED THE FUEL AT LEVEL OFF, I NOTICED WE STILL HAD THE SAME QUANTITY OF FUEL (PER THE FUEL GAUGES) AS WE HAD LEFT WITH. UPON LOOKING AT THE CIRCUIT BREAKER PANEL, I SAW THAT THE FUEL QUANTITY CIRCUIT BREAKER AND ONE OTHER FUEL ASSOCIATED CIRCUIT BREAKER WAS PULLED AND COLLARED. AFTER TALKING WITH MY FO AND A CHK AIRMAN, WHO WAS RIDING JUMPSEAT, WE DETERMINED THAT WE COULD RESET THE CIRCUIT BREAKER, SINCE IT HAD NOT BEEN TRIPPED. OTHERWISE, WE WOULD HAVE NO WAY OF KNOWING HOW MUCH FUEL WE ACTUALLY HAD. UPON ARR, WE HAD MAINT COME OUT AND CORRECT THE PROB BY INSTALLING A NEW FUEL SUMMATION UNIT. UPON TALKING WITH THE MECH, I FOUND OUT THAT THE MECH, WHO DEFERRED THE FUEL SUMMATION UNIT, WAS PULL THE CIRCUIT BREAKERS, DISCONNECT THE FUEL SUMMATION UNIT, AND THEN RESET THE CIRCUIT BREAKERS. LATER, UPON TALKING WITH MY FO, I FOUND OUT THAT THE MECH, IN OUR ORIGINATING CITY HAD FIRST DISCONNECTED THE FUEL SUMMATION UNIT AND THEN PULLED AND COLLARED THE CIRCUIT BREAKERS. I TRUST OUR MECHS TO DO THEIR WORK CORRECTLY, AND AS A PLT, I DO NOT ALWAYS HAVE THE LUXURY OR KNOWLEDGE TO CHK THAT THEY COMPLETE THEIR WORK CORRECTLY. SOMETIMES I ONLY HAVE THE SIGNED OFF LOGBOOK TO TELL ME THAT ALL MAINT HAS BEEN PERFORMED CORRECTLY. HOWEVER, IN THIS CASE, I COULD HAVE VERIFIED THAT HE INDEED HAD PULLED AND COLLARED THE CIRCUIT BREAKERS, AND IF THEY WERE TO BE COLLARED. SEEING THE FUEL QUANTITY CIRCUIT BREAKER PULLED AND COLLARED SHOULD HAVE RAISED A RED FLAG BEFORE DEP.

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.