Narrative:

Part number of cooling fan to be replaced was determined by individual from another station -- location other than amt accomplishing task. Avionics display fan MEL was assigned to work package for ZZZ station and cooling fan; as listed on MEL report; was sent to station for purpose of clearing MEL. Amt's installed cooling fan and during installation process noticed part numbers of new fan (EFIS display cooling fan versus avionics supply fan) did not match. Operations check after installation checked good and amt's assumed all was good and signed for work and cleared MEL with maintenance control. I reviewed the job cards assigned by the planning package for aircraft and after ensuring documentation was complete; I signed the airworthiness release and returned the logbook to the aircraft and closed it up. I then attempted to make entries in maintenance data computer; after the fact; for removal of defective cooling fan and installation of new cooling fan but was unable due to maintenance data computer identing that parts were not interchangeable and rejected my attempted entries. Cooling fan was effective for aircraft but not interchangeable for the installation location. I advised amt's of discrepancy and P1 looked up cooling fan in ipc and verified it was; in fact; incorrect where it was installed. When P1 asked what should be done; I advised him the old defective cooling fan needed to be reinstalled since the airplane could not fly with an incorrectly installed part and that we would need to contact maintenance control and re-defer the system under the original MEL entry date. PA and P2 immediately returned to the aircraft and reinstalled the defective fan. I concurred with the suggestion of P2 that he should correct the logbook and MEL documentation by simply lining through the logbook documentation written for removing and replacing the avionics supply fan. P2 then called maintenance control and advised them what had happened and the MEL was re-entered under the original date. We then updated the MEL information in maintenance data computer with the correct part number for an avionics supply fan and submitted a material request for the part. Maintenance data computer would not allow the new part number to be interchanged with the old part number and after the paperwork had been completed and the airworthiness release signed; it was determined that an incorrect part had been installed and the situation needed to be corrected before the airplane could fly. Correcting the error in documentation became our downfall in correcting a situation that could have been worse had we not discovered the discrepant part. Defective part was reinstalled in its original position and the system re-deferred through maintenance control. Documentation for the right&right was inadvertently entered in error; incorrectly. The airworthiness release had been signed prior to knowledge of the mistake and no further action was taken regarding that. The cause of the event can be attributed to many different factors including human factors such as lack of attention to minute; albeit important; details; fatigue; stress; lack of experience; insufficient staffing; task overload; and time constraints. Inaccurate information on the part number ordered for the MEL and the fact that both parts; even though not interchangeable; matched in appearance; installation method; electrical connector and operability in swapped position. These similarities allowed the situation to get to the point of where the documentation was entered and signed off in the logbook and the MEL cleared. After that; is when the problem begins; in correcting such a paperwork discrepancy nightmare where at that time of the morning with departure time near; one just wants the problem to go away. Always doublechk the accuracy of another individual's work; ie; before attempting installation of a part; verify the part number matches the ipc reference for the position and part number of the item being replaced and check the physical part number of the part being replaced. Had that happened prior to the start of the job; the documentation would not have been an issue; since an incorrect part would not have been installed; necessitating removal and reinstallation of the defective part. Regarding documentation; slow down and think carefully about what you are doing and don't feel rushed just because a departure time may possibly be delayed. If an unusual event such as this occurs; scrutinize procedures closely and should there be any doubt; contact a station supervisor and seek direction and verification from them. Supplemental information from acn 792528: the aircraft had an MEL for avionics fan inoperative. The whole issue should have been avoided if we would have followed procedures for that MEL and re-collared that circuit breaker. Callback conversation with reporter revealed the following information: reporter stated the left avionics fan was the one needing to be replaced. This is one of two fans that provide cooling air to the lower avionics racks.

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Original NASA ASRS Text

Title: TWO MECHANICS (ONE A LEAD); REPORT ON THE EFFORTS TO INSTALL A NEW LEFT AVIONICS COOLING FAN ON A CRJ-200 (CL-600-2B19); THAT TURNED OUT TO BE AN INCORRECT PART; REQUIRING INOP FAN TO BE REINSTALLED.

Narrative: PART NUMBER OF COOLING FAN TO BE REPLACED WAS DETERMINED BY INDIVIDUAL FROM ANOTHER STATION -- LOCATION OTHER THAN AMT ACCOMPLISHING TASK. AVIONICS DISPLAY FAN MEL WAS ASSIGNED TO WORK PACKAGE FOR ZZZ STATION AND COOLING FAN; AS LISTED ON MEL RPT; WAS SENT TO STATION FOR PURPOSE OF CLRING MEL. AMT'S INSTALLED COOLING FAN AND DURING INSTALLATION PROCESS NOTICED PART NUMBERS OF NEW FAN (EFIS DISPLAY COOLING FAN VERSUS AVIONICS SUPPLY FAN) DID NOT MATCH. OPS CHK AFTER INSTALLATION CHKED GOOD AND AMT'S ASSUMED ALL WAS GOOD AND SIGNED FOR WORK AND CLRED MEL WITH MAINT CTL. I REVIEWED THE JOB CARDS ASSIGNED BY THE PLANNING PACKAGE FOR ACFT AND AFTER ENSURING DOCUMENTATION WAS COMPLETE; I SIGNED THE AIRWORTHINESS RELEASE AND RETURNED THE LOGBOOK TO THE ACFT AND CLOSED IT UP. I THEN ATTEMPTED TO MAKE ENTRIES IN MAINT DATA COMPUTER; AFTER THE FACT; FOR REMOVAL OF DEFECTIVE COOLING FAN AND INSTALLATION OF NEW COOLING FAN BUT WAS UNABLE DUE TO MAINT DATA COMPUTER IDENTING THAT PARTS WERE NOT INTERCHANGEABLE AND REJECTED MY ATTEMPTED ENTRIES. COOLING FAN WAS EFFECTIVE FOR ACFT BUT NOT INTERCHANGEABLE FOR THE INSTALLATION LOCATION. I ADVISED AMT'S OF DISCREPANCY AND P1 LOOKED UP COOLING FAN IN IPC AND VERIFIED IT WAS; IN FACT; INCORRECT WHERE IT WAS INSTALLED. WHEN P1 ASKED WHAT SHOULD BE DONE; I ADVISED HIM THE OLD DEFECTIVE COOLING FAN NEEDED TO BE REINSTALLED SINCE THE AIRPLANE COULD NOT FLY WITH AN INCORRECTLY INSTALLED PART AND THAT WE WOULD NEED TO CONTACT MAINT CTL AND RE-DEFER THE SYS UNDER THE ORIGINAL MEL ENTRY DATE. PA AND P2 IMMEDIATELY RETURNED TO THE ACFT AND REINSTALLED THE DEFECTIVE FAN. I CONCURRED WITH THE SUGGESTION OF P2 THAT HE SHOULD CORRECT THE LOGBOOK AND MEL DOCUMENTATION BY SIMPLY LINING THROUGH THE LOGBOOK DOCUMENTATION WRITTEN FOR REMOVING AND REPLACING THE AVIONICS SUPPLY FAN. P2 THEN CALLED MAINT CTL AND ADVISED THEM WHAT HAD HAPPENED AND THE MEL WAS RE-ENTERED UNDER THE ORIGINAL DATE. WE THEN UPDATED THE MEL INFO IN MAINT DATA COMPUTER WITH THE CORRECT PART NUMBER FOR AN AVIONICS SUPPLY FAN AND SUBMITTED A MATERIAL REQUEST FOR THE PART. MAINT DATA COMPUTER WOULD NOT ALLOW THE NEW PART NUMBER TO BE INTERCHANGED WITH THE OLD PART NUMBER AND AFTER THE PAPERWORK HAD BEEN COMPLETED AND THE AIRWORTHINESS RELEASE SIGNED; IT WAS DETERMINED THAT AN INCORRECT PART HAD BEEN INSTALLED AND THE SIT NEEDED TO BE CORRECTED BEFORE THE AIRPLANE COULD FLY. CORRECTING THE ERROR IN DOCUMENTATION BECAME OUR DOWNFALL IN CORRECTING A SIT THAT COULD HAVE BEEN WORSE HAD WE NOT DISCOVERED THE DISCREPANT PART. DEFECTIVE PART WAS REINSTALLED IN ITS ORIGINAL POS AND THE SYS RE-DEFERRED THROUGH MAINT CTL. DOCUMENTATION FOR THE R&R WAS INADVERTENTLY ENTERED IN ERROR; INCORRECTLY. THE AIRWORTHINESS RELEASE HAD BEEN SIGNED PRIOR TO KNOWLEDGE OF THE MISTAKE AND NO FURTHER ACTION WAS TAKEN REGARDING THAT. THE CAUSE OF THE EVENT CAN BE ATTRIBUTED TO MANY DIFFERENT FACTORS INCLUDING HUMAN FACTORS SUCH AS LACK OF ATTN TO MINUTE; ALBEIT IMPORTANT; DETAILS; FATIGUE; STRESS; LACK OF EXPERIENCE; INSUFFICIENT STAFFING; TASK OVERLOAD; AND TIME CONSTRAINTS. INACCURATE INFO ON THE PART NUMBER ORDERED FOR THE MEL AND THE FACT THAT BOTH PARTS; EVEN THOUGH NOT INTERCHANGEABLE; MATCHED IN APPEARANCE; INSTALLATION METHOD; ELECTRICAL CONNECTOR AND OPERABILITY IN SWAPPED POS. THESE SIMILARITIES ALLOWED THE SIT TO GET TO THE POINT OF WHERE THE DOCUMENTATION WAS ENTERED AND SIGNED OFF IN THE LOGBOOK AND THE MEL CLRED. AFTER THAT; IS WHEN THE PROB BEGINS; IN CORRECTING SUCH A PAPERWORK DISCREPANCY NIGHTMARE WHERE AT THAT TIME OF THE MORNING WITH DEP TIME NEAR; ONE JUST WANTS THE PROB TO GO AWAY. ALWAYS DOUBLECHK THE ACCURACY OF ANOTHER INDIVIDUAL'S WORK; IE; BEFORE ATTEMPTING INSTALLATION OF A PART; VERIFY THE PART NUMBER MATCHES THE IPC REF FOR THE POS AND PART NUMBER OF THE ITEM BEING REPLACED AND CHK THE PHYSICAL PART NUMBER OF THE PART BEING REPLACED. HAD THAT HAPPENED PRIOR TO THE START OF THE JOB; THE DOCUMENTATION WOULD NOT HAVE BEEN AN ISSUE; SINCE AN INCORRECT PART WOULD NOT HAVE BEEN INSTALLED; NECESSITATING REMOVAL AND REINSTALLATION OF THE DEFECTIVE PART. REGARDING DOCUMENTATION; SLOW DOWN AND THINK CAREFULLY ABOUT WHAT YOU ARE DOING AND DON'T FEEL RUSHED JUST BECAUSE A DEP TIME MAY POSSIBLY BE DELAYED. IF AN UNUSUAL EVENT SUCH AS THIS OCCURS; SCRUTINIZE PROCS CLOSELY AND SHOULD THERE BE ANY DOUBT; CONTACT A STATION SUPVR AND SEEK DIRECTION AND VERIFICATION FROM THEM. SUPPLEMENTAL INFO FROM ACN 792528: THE ACFT HAD AN MEL FOR AVIONICS FAN INOP. THE WHOLE ISSUE SHOULD HAVE BEEN AVOIDED IF WE WOULD HAVE FOLLOWED PROCS FOR THAT MEL AND RE-COLLARED THAT CIRCUIT BREAKER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE LEFT AVIONICS FAN WAS THE ONE NEEDING TO BE REPLACED. THIS IS ONE OF TWO FANS THAT PROVIDE COOLING AIR TO THE LOWER AVIONICS RACKS.

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.