Narrative:

On may/xa/98 and may/xb/98 I had to verify that air carrier aircraft xyz and zxy had a modified thrust management computer installed. I had to check the data plates on the units and install new computers if the part numbers on them weren't correct. I believed the aircraft were in compliance with my inspection and signed the logbooks to reflect this and that no computer replacement was required. During a company sponsored follow-up inspection, it was determined that both of these thrust management computers were unmodified and needed to be replaced according to their part numbers. These unmodified part numbers were yyzzxx-G2. The modified part numbers are yyzzxx-G3 and yyzzyx-G2, which are very similar to the old number. I must have been confused on the nights in question and misinterped the bad number for a good one. I had performed this inspection many times prior to these incidents without complication. I believe these incidents occurred because I was comfortable with the procedure and perhaps a little complacent. Furthermore, I work shift XA00-XI00 and have trouble staying focused all the time.

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Original NASA ASRS Text

Title: 2 B757-200 ACFT WERE DISPATCHED WITH UNMODIFIED THRUST MGMNT COMPUTERS CAUSED BY INSPECTION OVERSIGHT.

Narrative: ON MAY/XA/98 AND MAY/XB/98 I HAD TO VERIFY THAT ACR ACFT XYZ AND ZXY HAD A MODIFIED THRUST MGMNT COMPUTER INSTALLED. I HAD TO CHK THE DATA PLATES ON THE UNITS AND INSTALL NEW COMPUTERS IF THE PART NUMBERS ON THEM WEREN'T CORRECT. I BELIEVED THE ACFT WERE IN COMPLIANCE WITH MY INSPECTION AND SIGNED THE LOGBOOKS TO REFLECT THIS AND THAT NO COMPUTER REPLACEMENT WAS REQUIRED. DURING A COMPANY SPONSORED FOLLOW-UP INSPECTION, IT WAS DETERMINED THAT BOTH OF THESE THRUST MGMNT COMPUTERS WERE UNMODIFIED AND NEEDED TO BE REPLACED ACCORDING TO THEIR PART NUMBERS. THESE UNMODIFIED PART NUMBERS WERE YYZZXX-G2. THE MODIFIED PART NUMBERS ARE YYZZXX-G3 AND YYZZYX-G2, WHICH ARE VERY SIMILAR TO THE OLD NUMBER. I MUST HAVE BEEN CONFUSED ON THE NIGHTS IN QUESTION AND MISINTERPED THE BAD NUMBER FOR A GOOD ONE. I HAD PERFORMED THIS INSPECTION MANY TIMES PRIOR TO THESE INCIDENTS WITHOUT COMPLICATION. I BELIEVE THESE INCIDENTS OCCURRED BECAUSE I WAS COMFORTABLE WITH THE PROC AND PERHAPS A LITTLE COMPLACENT. FURTHERMORE, I WORK SHIFT XA00-XI00 AND HAVE TROUBLE STAYING FOCUSED ALL THE TIME.

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.