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A flightdeck mechanic responsible for coordinating operational checks during their maintenance checks; reports about damage to a B777-200 from the RAT motor blades during a center hydraulic system servicing procedure.
| Attributes | |
| ACN | 880029 |
| Time | |
| Date | 201003 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B777-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Component | |
| Aircraft Component | Hydraulic Auxiliary System Ram Air Turbine (RAT) |
| Person 1 | |
| Function | Technician |
| Qualification | Maintenance Airframe Maintenance Powerplant |
| Person 2 | |
| Function | Technician |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy |
Narrative:
I am the flightdeck mechanic and as so my observations are from the flightdeck only. After performing the RAT system motoring test; the center reservoir was depleted due to using the hydraulic mule to back drive the RAT. We were attempting to service the center reservoir back up by closing the return on the mule and operating a flight control; but the only flight control available at this stage of the visit was the left elevator. It was going to take hours to fill the reservoir via the mule through the single elevator; so we decided to drop the RAT again and back drive it which would fill the reservoir in a timely manner. We have performed this process many times and it works quite well. I obtained clearance and deployed the RAT. The ground crew already had center hydraulic on; via the hydraulic mule. As they began back driving the RAT; I heard the RAT blades make an unusual sound and the RAT motoring was immediately terminated. I ask the ground crew what happened and they informed me that the RAT was not locked down and as they began to back drive it; the rat drove forward enough for the blades to contact the fillet panel which caused damage to the panel and the RAT blades. All hydraulic power was immediately shut down to assess the damage.
Original NASA ASRS Text
Title: A Flightdeck Mechanic responsible for coordinating Operational Checks during their Maintenance Checks; reports about damage to a B777-200 from the RAT Motor blades during a Center hydraulic system servicing procedure.
Narrative: I am the Flightdeck Mechanic and as so my observations are from the flightdeck only. After performing the RAT system motoring test; the Center reservoir was depleted due to using the Hydraulic Mule to back drive the RAT. We were attempting to service the Center reservoir back up by closing the return on the Mule and operating a Flight Control; but the only Flight Control available at this stage of the visit was the left Elevator. It was going to take hours to fill the reservoir via the Mule through the single Elevator; so we decided to drop the RAT again and back drive it which would fill the reservoir in a timely manner. We have performed this process many times and it works quite well. I obtained clearance and deployed the RAT. The Ground Crew already had Center hydraulic on; via the hydraulic Mule. As they began back driving the RAT; I heard the RAT blades make an unusual sound and the RAT motoring was immediately terminated. I ask the Ground Crew what happened and they informed me that the RAT was not locked down and as they began to back drive it; the Rat drove forward enough for the blades to contact the fillet panel which caused damage to the panel and the RAT blades. All hydraulic power was immediately shut down to assess the damage.
Data retrieved from NASA's ASRS site as of April 2012 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.