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B757 captain reported an issue with the autopilot in a coupled approach. A missed approach was necessary followed by a hand flown successful approach and landing.
| Attributes | |
| ACN | 1457444 |
| Time | |
| Date | 201706 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Final Approach |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autopilot |
| Person 1 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Our departure was delayed due to maintenance checks of autopilot/autoland system. Maintenance advised us that system checked out okay after resetting the main aircraft buses and that previous failure was due to possible sticky relay(s). On approach at glideslope capture and triple channel isolation; the autopilot failed; autothrottle failed; auto brakes kicked off. Captain side displays stopped working; multiple messages on upper EICAS (these items eventually resolved when electrical system reverted to normal configuration). We discontinued the approach. Reset the flight directors. Status messages remaining after system was reset were: main bat chrgr; eqpt smoke test; stby inverter. We were vectored around for a second approach. This approach was hand flown using flight director with no issues.
Original NASA ASRS Text
Title: B757 Captain reported an issue with the autopilot in a coupled approach. A missed approach was necessary followed by a hand flown successful approach and landing.
Narrative: Our departure was delayed due to maintenance checks of autopilot/autoland system. Maintenance advised us that system checked out okay after resetting the main aircraft buses and that previous failure was due to possible sticky relay(s). On approach at glideslope capture and triple channel isolation; the autopilot failed; autothrottle failed; auto brakes kicked off. Captain side displays stopped working; multiple messages on upper EICAS (these items eventually resolved when electrical system reverted to normal configuration). We discontinued the approach. Reset the flight directors. Status messages remaining after system was reset were: MAIN BAT CHRGR; EQPT SMOKE TEST; STBY INVERTER. We were vectored around for a second approach. This approach was hand flown using flight director with no issues.
Data retrieved from NASA's ASRS site 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.