A B737-400 had the right center tank pump replaced improperly resulting in a fuel leak.

Attributes
ACN	413064
Time
Date	199809
Day	Wed
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	other
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	413064
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : less severe non adherence : published procedure non adherence : far
Independent Detector	other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Aircraft xyz came in for a 'C' check with the right center tank boost pump on MEL as dysfunctional. A new pump was issued along with a seal kit. After removing defective pump and placing it alongside its replacement, it was noted that the delivery port stem of the pump provided 2 grooves for o-ring accommodation, whereas the return port 1. The maintenance manual only instructs to replace o-rings before installation. Since the o-ring kit provided 1 replacement seal of matching diameter and cross section to those seals on the defective pump, the assumption was that the seals on the removed pump were correctly placed and therefore to install the seals on the replacement pump in a way identical to the way found. After lubing the seals and installing the pump, it was functionally checked by listening to the pump motor run when the boost pump switch was placed to the 'on' position momentarily at the flight station. As there was only 210 pounds of fuel in the center tank, no leak check was established at this time and no notation made in the logbook to this effect, only its operation. At the gate, fuel was put into the center tank and the pump was found to be leaking by maintenance personnel during walkaround. The pump was removed and with the new o-ring seal provided, the seal position was changed on the delivery port from one groove position to the other. The pump was installed and functioned without leakage after which the aircraft departed ZZZ.

Original NASA ASRS Text

Title: A B737-400 HAD THE R CTR TANK PUMP REPLACED IMPROPERLY RESULTING IN A FUEL LEAK.

Narrative: ACFT XYZ CAME IN FOR A 'C' CHK WITH THE R CTR TANK BOOST PUMP ON MEL AS DYSFUNCTIONAL. A NEW PUMP WAS ISSUED ALONG WITH A SEAL KIT. AFTER REMOVING DEFECTIVE PUMP AND PLACING IT ALONGSIDE ITS REPLACEMENT, IT WAS NOTED THAT THE DELIVERY PORT STEM OF THE PUMP PROVIDED 2 GROOVES FOR O-RING ACCOMMODATION, WHEREAS THE RETURN PORT 1. THE MAINT MANUAL ONLY INSTRUCTS TO REPLACE O-RINGS BEFORE INSTALLATION. SINCE THE O-RING KIT PROVIDED 1 REPLACEMENT SEAL OF MATCHING DIAMETER AND CROSS SECTION TO THOSE SEALS ON THE DEFECTIVE PUMP, THE ASSUMPTION WAS THAT THE SEALS ON THE REMOVED PUMP WERE CORRECTLY PLACED AND THEREFORE TO INSTALL THE SEALS ON THE REPLACEMENT PUMP IN A WAY IDENTICAL TO THE WAY FOUND. AFTER LUBING THE SEALS AND INSTALLING THE PUMP, IT WAS FUNCTIONALLY CHKED BY LISTENING TO THE PUMP MOTOR RUN WHEN THE BOOST PUMP SWITCH WAS PLACED TO THE 'ON' POS MOMENTARILY AT THE FLT STATION. AS THERE WAS ONLY 210 LBS OF FUEL IN THE CTR TANK, NO LEAK CHK WAS ESTABLISHED AT THIS TIME AND NO NOTATION MADE IN THE LOGBOOK TO THIS EFFECT, ONLY ITS OP. AT THE GATE, FUEL WAS PUT INTO THE CTR TANK AND THE PUMP WAS FOUND TO BE LEAKING BY MAINT PERSONNEL DURING WALKAROUND. THE PUMP WAS REMOVED AND WITH THE NEW O-RING SEAL PROVIDED, THE SEAL POS WAS CHANGED ON THE DELIVERY PORT FROM ONE GROOVE POS TO THE OTHER. THE PUMP WAS INSTALLED AND FUNCTIONED WITHOUT LEAKAGE AFTER WHICH THE ACFT DEPARTED ZZZ.

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.