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A B737-200 technician making a trailing edge flap inspection found a flap drive shaft not secured at the input to the angle drive gearbox.
| Attributes | |
| ACN | 618505 |
| Time | |
| Date | 200405 |
| Day | Fri |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : powerplant technician : airframe |
| Experience | maintenance technician : 17 |
| ASRS Report | 618505 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : far non adherence : published procedure |
| Independent Detector | other other : person 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : work cards performance deficiency : scheduled maintenance performance deficiency : non compliance with legal requirements performance deficiency : inspection performance deficiency : installation performance deficiency : logbook entry |
| Supplementary | |
| Problem Areas | Company Environmental Factor Maintenance Human Performance Aircraft |
| Primary Problem | Maintenance Human Performance |
Narrative:
During walkaround on aircraft. I checked the flap drive torque tube from the main flap drive motor to the angle drive gearbox (#5 track position) for looseness at the couplings and while doing so the torque tube became disconnected from the angle drive gearbox. Upon further inspection the only thing keeping the coupling in place was the grease! After I accessed the area (pulling shroud) I found 2 of the screws but no evidence of safety wire. This area is not normally accessed by line maintenance. I believe contract (out-sourced) maintenance may be to blame for this incident, as the aircraft had recently come out of c-chk in may 2004. Reviewing the maintenance program in place for the contract maintenance would be a good place to start. This discrepancy which I found I believe could have been disastrous. Callback conversation with reporter revealed the following information: the reporter stated the check of the flap drive torque tube is not part of the airworthiness directive on the outboard flap drive spindle inspection. The reporter said with the flaps down a visual and shake check of the torque tube train is easy to do, and in this event may have prevented serious problems. The reporter stated when shaking the input drive shaft to the right wing angle gearbox the shaft slipped right out and was only held in place by a coating of grease. The reporter said the lock plate has a total of three fasteners that were not in place, two were found laying in the flap well and one was missing. The reporter stated there was no evidence of safety wire being used on the fasteners or in the flap well. The reporter said this airplane was fresh out of a 'C' maintenance check that required access to the torque tubes, flap drive transmissions and angle gearboxes for lubrication and wear checks. The reporter stated these heavy checks are bid out to contract maintenance repair shops where this airplane was worked.
Original NASA ASRS Text
Title: A B737-200 TECHNICIAN MAKING A TRAILING EDGE FLAP INSPECTION FOUND A FLAP DRIVE SHAFT NOT SECURED AT THE INPUT TO THE ANGLE DRIVE GEARBOX.
Narrative: DURING WALKAROUND ON ACFT. I CHKED THE FLAP DRIVE TORQUE TUBE FROM THE MAIN FLAP DRIVE MOTOR TO THE ANGLE DRIVE GEARBOX (#5 TRACK POS) FOR LOOSENESS AT THE COUPLINGS AND WHILE DOING SO THE TORQUE TUBE BECAME DISCONNECTED FROM THE ANGLE DRIVE GEARBOX. UPON FURTHER INSPECTION THE ONLY THING KEEPING THE COUPLING IN PLACE WAS THE GREASE! AFTER I ACCESSED THE AREA (PULLING SHROUD) I FOUND 2 OF THE SCREWS BUT NO EVIDENCE OF SAFETY WIRE. THIS AREA IS NOT NORMALLY ACCESSED BY LINE MAINT. I BELIEVE CONTRACT (OUT-SOURCED) MAINT MAY BE TO BLAME FOR THIS INCIDENT, AS THE ACFT HAD RECENTLY COME OUT OF C-CHK IN MAY 2004. REVIEWING THE MAINT PROGRAM IN PLACE FOR THE CONTRACT MAINT WOULD BE A GOOD PLACE TO START. THIS DISCREPANCY WHICH I FOUND I BELIEVE COULD HAVE BEEN DISASTROUS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CHK OF THE FLAP DRIVE TORQUE TUBE IS NOT PART OF THE AIRWORTHINESS DIRECTIVE ON THE OUTBOARD FLAP DRIVE SPINDLE INSPECTION. THE RPTR SAID WITH THE FLAPS DOWN A VISUAL AND SHAKE CHK OF THE TORQUE TUBE TRAIN IS EASY TO DO, AND IN THIS EVENT MAY HAVE PREVENTED SERIOUS PROBS. THE RPTR STATED WHEN SHAKING THE INPUT DRIVE SHAFT TO THE RIGHT WING ANGLE GEARBOX THE SHAFT SLIPPED RIGHT OUT AND WAS ONLY HELD IN PLACE BY A COATING OF GREASE. THE RPTR SAID THE LOCK PLATE HAS A TOTAL OF THREE FASTENERS THAT WERE NOT IN PLACE, TWO WERE FOUND LAYING IN THE FLAP WELL AND ONE WAS MISSING. THE RPTR STATED THERE WAS NO EVIDENCE OF SAFETY WIRE BEING USED ON THE FASTENERS OR IN THE FLAP WELL. THE RPTR SAID THIS AIRPLANE WAS FRESH OUT OF A 'C' MAINT CHK THAT REQUIRED ACCESS TO THE TORQUE TUBES, FLAP DRIVE TRANSMISSIONS AND ANGLE GEARBOXES FOR LUBRICATION AND WEAR CHKS. THE RPTR STATED THESE HEAVY CHKS ARE BID OUT TO CONTRACT MAINT REPAIR SHOPS WHERE THIS AIRPLANE WAS WORKED.
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.