Narrative:

Maintenance was performed and during the time after the lead check was performed the low pressure turbine disc was placed on a pie cart for waiting for the other 3 stages to build up the low pressure turbine module. During this time, many shifts went by and when the air seal was installed, no one saw that the blade retainer was now missing. No paperwork was issued for a second build, and therefore my signature was on the job card, and the lead mechanic also verified and signed. Callback conversation with reporter revealed the following information: the reporter stated the defective low pressure turbine disc with the missing blade retainer was installed on the low pressure turbine module and in turn added to a complete engine. The reporter said the engine completed all run tests and inspections and was installed on an airplane in #2 engine position. The reporter said the engine operated for 3000 hours when it developed a vibration and a borescope inspection revealed low pressure turbine disc and stator damage. The reporter stated when the engine was torn down it was discovered the turbine disc migrated aft and started rubbing on the stator vanes due to the blade retainer missing. The reporter stated after he built up the disc and the lead technician made the final inspection it was routed for dynamic balancing. The reporter said at that time there was no job card for the dynamic balancing segment of the operation. The reporter stated the balancing requires shuffling some blades around on the disc to achieve balance and this is where the retainer was lost. The reporter said the company investigation has corrected this situation and closed this paperwork gap.

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Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED AND OPERATED FOR 3000 HRS IN NON COMPLIANCE WITH #2 ENG LOW PRESSURE TURBINE DISC BLADE RETAINER NOT INSTALLED.

Narrative: MAINT WAS PERFORMED AND DURING THE TIME AFTER THE LEAD CHK WAS PERFORMED THE LOW PRESSURE TURBINE DISC WAS PLACED ON A PIE CART FOR WAITING FOR THE OTHER 3 STAGES TO BUILD UP THE LOW PRESSURE TURBINE MODULE. DURING THIS TIME, MANY SHIFTS WENT BY AND WHEN THE AIR SEAL WAS INSTALLED, NO ONE SAW THAT THE BLADE RETAINER WAS NOW MISSING. NO PAPERWORK WAS ISSUED FOR A SECOND BUILD, AND THEREFORE MY SIGNATURE WAS ON THE JOB CARD, AND THE LEAD MECH ALSO VERIFIED AND SIGNED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE DEFECTIVE LOW PRESSURE TURBINE DISC WITH THE MISSING BLADE RETAINER WAS INSTALLED ON THE LOW PRESSURE TURBINE MODULE AND IN TURN ADDED TO A COMPLETE ENG. THE RPTR SAID THE ENG COMPLETED ALL RUN TESTS AND INSPECTIONS AND WAS INSTALLED ON AN AIRPLANE IN #2 ENG POS. THE RPTR SAID THE ENG OPERATED FOR 3000 HRS WHEN IT DEVELOPED A VIBRATION AND A BORESCOPE INSPECTION REVEALED LOW PRESSURE TURBINE DISC AND STATOR DAMAGE. THE RPTR STATED WHEN THE ENG WAS TORN DOWN IT WAS DISCOVERED THE TURBINE DISC MIGRATED AFT AND STARTED RUBBING ON THE STATOR VANES DUE TO THE BLADE RETAINER MISSING. THE RPTR STATED AFTER HE BUILT UP THE DISC AND THE LEAD TECHNICIAN MADE THE FINAL INSPECTION IT WAS ROUTED FOR DYNAMIC BALANCING. THE RPTR SAID AT THAT TIME THERE WAS NO JOB CARD FOR THE DYNAMIC BALANCING SEGMENT OF THE OP. THE RPTR STATED THE BALANCING REQUIRES SHUFFLING SOME BLADES AROUND ON THE DISC TO ACHIEVE BAL AND THIS IS WHERE THE RETAINER WAS LOST. THE RPTR SAID THE COMPANY INVESTIGATION HAS CORRECTED THIS SIT AND CLOSED THIS PAPERWORK GAP.

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.