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A line aircraft maintenance technician (amt) suggests a revision that would add another block decision step to boeing's fault isolation manual (fim) for B767 aircraft. The revision would reduce the required additional tests for rudder ratio changer module faults that commonly appear after initial aircraft power-up.
| Attributes | |
| ACN | 1051822 |
| Time | |
| Date | 201211 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Light | Dusk |
| Aircraft 1 | |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Component | |
| Aircraft Component | EICAS/EAD/ECAM |
| Person 1 | |
| Function | Technician |
| Qualification | Maintenance Airframe Maintenance Powerplant |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
While performing other tasks; I noticed the 'module fault' fault ball tripped on a rudder ratio changer module (rrcm). Following the fault isolation manual (fim); a step seems to be missing/not making sense; or possibly could use an additional decision block. Block-3 asks if fault ball is currently set after system test (in this case; 'no'). Block-4 asks if fault ball was set prior to test; (in this case; 'yes') and if 'yes'; the fim doesn't afford the ability to determine the system 'ok' via the previously performed test; but instead requires; regardless of subsequent decision; block-56 (in this case; 'no'); further tests/troubleshooting even with no faults current on the [rrcm module] box. This [rrcm] fault ball being set is fairly common on initial power-up of the B-767 fleet; (along with the 'stabilizer trim' EICAS message as well). Perhaps add a block to the fault isolation tree to determine if the fault/fault ball has recurred in the last xx days/flights before mandating additional checks/tests? Or a block; checking if the aircraft was just 'powered up'; and if so; the system is 'ok'.
Original NASA ASRS Text
Title: A Line Aircraft Maintenance Technician (AMT) suggests a revision that would add another Block Decision Step to Boeing's Fault Isolation Manual (FIM) for B767 aircraft. The revision would reduce the required additional tests for Rudder Ratio Changer Module faults that commonly appear after initial aircraft power-up.
Narrative: While performing other tasks; I noticed the 'Module Fault' fault ball tripped on a Rudder Ratio Changer Module (RRCM). Following the Fault Isolation Manual (FIM); a Step seems to be missing/not making sense; or possibly could use an additional decision block. Block-3 asks if fault ball is currently set after System Test (in this case; 'No'). Block-4 asks if fault ball was set prior to test; (in this case; 'Yes') and if 'Yes'; the FIM doesn't afford the ability to determine the system 'OK' via the previously performed test; but instead requires; regardless of subsequent decision; Block-56 (in this case; 'No'); further tests/troubleshooting even with no faults current on the [RRCM Module] box. This [RRCM] fault ball being set is fairly common on initial power-up of the B-767 fleet; (along with the 'STAB TRIM' EICAS message as well). Perhaps add a block to the Fault Isolation Tree to determine if the fault/fault ball has recurred in the last XX days/flights before mandating additional Checks/Tests? or a block; checking if the aircraft was just 'powered up'; and if so; the system is 'OK'.
Data retrieved from NASA's ASRS site as of July 2013 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.