Narrative:

#1 fan change on air carrier X due to a bent fan blade. Aircraft in ZZZ hangar. ZZZ line working lightning strike damage. When we arrived the nose cowl was removed. Engine had been previously borescoped by ZZZ inspector with no trouble found. The borescope as requested by maintenance control due to PIREP that engine rolled back when aircraft struck by lightning. I personally observed the engine fan change as did ZZZ inspector who performed the rii duties. During the installation of the inlet group I assisted with installation of the lower bolts. To make access to tightening the bolts easier I installed the PT2 sense lines to the inlet group finger tight. After the inlet group the #1 bearing was installed and the remainder of the operation was accomplished. I overlooked wrenching the PT2 lines tight. Another amt safetied the PT2 lines. Engine preflight was accomplished, all parameters normal. On 1ST flight pilot reported climbing through 19000 ft that with N1, N2, and egt matched the engine EPR's were split. The opted to return to ZZZ.

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Original NASA ASRS Text

Title: AN MD88 RETURNED TO THE FIELD DUE TO ENG PRESSURE RATIO INDICATIONS SPLIT. FOUND #1 ENG PRESSURE 2 LINE 'B' NUT LOOSE.

Narrative: #1 FAN CHANGE ON ACR X DUE TO A BENT FAN BLADE. ACFT IN ZZZ HANGAR. ZZZ LINE WORKING LIGHTNING STRIKE DAMAGE. WHEN WE ARRIVED THE NOSE COWL WAS REMOVED. ENG HAD BEEN PREVIOUSLY BORESCOPED BY ZZZ INSPECTOR WITH NO TROUBLE FOUND. THE BORESCOPE AS REQUESTED BY MAINT CTL DUE TO PIREP THAT ENG ROLLED BACK WHEN ACFT STRUCK BY LIGHTNING. I PERSONALLY OBSERVED THE ENG FAN CHANGE AS DID ZZZ INSPECTOR WHO PERFORMED THE RII DUTIES. DURING THE INSTALLATION OF THE INLET GROUP I ASSISTED WITH INSTALLATION OF THE LOWER BOLTS. TO MAKE ACCESS TO TIGHTENING THE BOLTS EASIER I INSTALLED THE PT2 SENSE LINES TO THE INLET GROUP FINGER TIGHT. AFTER THE INLET GROUP THE #1 BEARING WAS INSTALLED AND THE REMAINDER OF THE OP WAS ACCOMPLISHED. I OVERLOOKED WRENCHING THE PT2 LINES TIGHT. ANOTHER AMT SAFETIED THE PT2 LINES. ENG PREFLT WAS ACCOMPLISHED, ALL PARAMETERS NORMAL. ON 1ST FLT PLT RPTED CLBING THROUGH 19000 FT THAT WITH N1, N2, AND EGT MATCHED THE ENG EPR'S WERE SPLIT. THE OPTED TO RETURN TO 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.