A B737-300 was dispatched with the wrong captain's instrument comparator annunciator installed.

Attributes
ACN	394908
Time
Date	199802
Day	Thu
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	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
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	394908
Person 2
Affiliation	company : air carrier
Function	other personnel other other personnel other
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

While performing a maintenance check on a B737-300 on feb/xx/98, one of the discrepancies I found was that the captain's and first officer's instrument comparator annunciators had the heading lights inoperative. After getting the part number off the old part, I checked the computer for availability and saw we had one, went to the stock room and inadvertently picked up the wrong part. I relied on memory of its location and label on the shelf and did not realize that it was an annunciator for a B737-200. I failed to rechk the part number and installed the part on the captain's side. I tested the annunciator and it tested good. I then placed the first officer's comparator on MEL and downgraded the aircraft to CAT I status via an MEL. The next night when I reported for duty, the stock clerk informed me that the part on was not the same as the part off. I immediately contacted maintenance control to get the mistake corrected. The station had already replaced the first officer's side and we had to MEL the captain's side and the aircraft remained on CAT I status. The aircraft was to have the incorrect annunciator replaced as soon as possible. In retrospect, the problem could have been avoided had I taken the time to verify the part number and not relied on my memory of stock room location.

Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED WITH THE WRONG CAPT'S INST COMPARATOR ANNUNCIATOR INSTALLED.

Narrative: WHILE PERFORMING A MAINT CHK ON A B737-300 ON FEB/XX/98, ONE OF THE DISCREPANCIES I FOUND WAS THAT THE CAPT'S AND FO'S INST COMPARATOR ANNUNCIATORS HAD THE HDG LIGHTS INOP. AFTER GETTING THE PART NUMBER OFF THE OLD PART, I CHKED THE COMPUTER FOR AVAILABILITY AND SAW WE HAD ONE, WENT TO THE STOCK ROOM AND INADVERTENTLY PICKED UP THE WRONG PART. I RELIED ON MEMORY OF ITS LOCATION AND LABEL ON THE SHELF AND DID NOT REALIZE THAT IT WAS AN ANNUNCIATOR FOR A B737-200. I FAILED TO RECHK THE PART NUMBER AND INSTALLED THE PART ON THE CAPT'S SIDE. I TESTED THE ANNUNCIATOR AND IT TESTED GOOD. I THEN PLACED THE FO'S COMPARATOR ON MEL AND DOWNGRADED THE ACFT TO CAT I STATUS VIA AN MEL. THE NEXT NIGHT WHEN I RPTED FOR DUTY, THE STOCK CLERK INFORMED ME THAT THE PART ON WAS NOT THE SAME AS THE PART OFF. I IMMEDIATELY CONTACTED MAINT CTL TO GET THE MISTAKE CORRECTED. THE STATION HAD ALREADY REPLACED THE FO'S SIDE AND WE HAD TO MEL THE CAPT'S SIDE AND THE ACFT REMAINED ON CAT I STATUS. THE ACFT WAS TO HAVE THE INCORRECT ANNUNCIATOR REPLACED ASAP. IN RETROSPECT, THE PROB COULD HAVE BEEN AVOIDED HAD I TAKEN THE TIME TO VERIFY THE PART NUMBER AND NOT RELIED ON MY MEMORY OF STOCK ROOM LOCATION.

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.