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A technician reports that P&west 4056 engine fan case strut metal replacement cover plates have inadequate rivets to prevent loss of the cover plate.
| Attributes | |
| ACN | 493707 |
| Time | |
| Date | 200011 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B747-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance ground : parked |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| Experience | maintenance technician : 10 |
| ASRS Report | 493707 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | other personnel other |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | other other : person 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : engineering procedure contributing factor : manuals performance deficiency : installation performance deficiency : repair |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Environmental Factor Chart Or Publication Aircraft |
| Primary Problem | Maintenance Human Performance |
| Situations | |
| Publication | MAINT MANUAL CHAP 72 |
Narrative:
The #2 engine of aircraft xyz had fan case exit support struts with eroded carbon-fiber cover plates. The old carbon-fiber plates were removed and the new metal replacement plates were installed exactly per the maintenance manual. These plates have been found missing after flts several times before on other aircraft. The problem I see here is the type of rivet that is called for to hold these panels on. The rivets are a pull type with no locking center and are very weak since they are hollow aluminum. The airspeed at the fan case exit is very high and the rivets and rtv used to hold these panels on is not enough. If a panel were to come off in-flight it would probably cause no damage to the aircraft itself since the plates are after the fan blades. However, I worry that a plate falling from the sky could ultimately end up killing someone. I feel there is a need for either locking rivets or screws to be used as fasteners. I do not trust the repair for these reasons.
Original NASA ASRS Text
Title: A TECHNICIAN RPTS THAT P&W 4056 ENG FAN CASE STRUT METAL REPLACEMENT COVER PLATES HAVE INADEQUATE RIVETS TO PREVENT LOSS OF THE COVER PLATE.
Narrative: THE #2 ENG OF ACFT XYZ HAD FAN CASE EXIT SUPPORT STRUTS WITH ERODED CARBON-FIBER COVER PLATES. THE OLD CARBON-FIBER PLATES WERE REMOVED AND THE NEW METAL REPLACEMENT PLATES WERE INSTALLED EXACTLY PER THE MAINT MANUAL. THESE PLATES HAVE BEEN FOUND MISSING AFTER FLTS SEVERAL TIMES BEFORE ON OTHER ACFT. THE PROB I SEE HERE IS THE TYPE OF RIVET THAT IS CALLED FOR TO HOLD THESE PANELS ON. THE RIVETS ARE A PULL TYPE WITH NO LOCKING CTR AND ARE VERY WEAK SINCE THEY ARE HOLLOW ALUMINUM. THE AIRSPD AT THE FAN CASE EXIT IS VERY HIGH AND THE RIVETS AND RTV USED TO HOLD THESE PANELS ON IS NOT ENOUGH. IF A PANEL WERE TO COME OFF INFLT IT WOULD PROBABLY CAUSE NO DAMAGE TO THE ACFT ITSELF SINCE THE PLATES ARE AFTER THE FAN BLADES. HOWEVER, I WORRY THAT A PLATE FALLING FROM THE SKY COULD ULTIMATELY END UP KILLING SOMEONE. I FEEL THERE IS A NEED FOR EITHER LOCKING RIVETS OR SCREWS TO BE USED AS FASTENERS. I DO NOT TRUST THE REPAIR FOR THESE REASONS.
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.