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SA227 captain reported an inverter failure on final approach causing them to deviate from the localizer on the ILS.
| Attributes | |
| ACN | 1619157 |
| Time | |
| Date | 201902 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | SA-227 AC Metro III |
| Operating Under FAR Part | Part 135 |
| Flight Phase | Initial Approach |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Inverter |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types Inflight Event / Encounter Unstabilized Approach |
Narrative:
At the time of the event; the first officer (first officer) was the pilot flying; we were cleared for the ILS approach; were on localizer; and were descending to 2400. Right before the FAF (final approach fix); we both heard a 'pop.' the first officer's attitude indicator was flagged; as was the pilot's attitude indicator. At first; we thought circuit breakers had popped; so we looked and saw none popped. A second later; we saw left AC bus and right AC bus illuminated; so that meant inverter #1 had failed. The captain took control of the aircraft; and we switched to the #2 inverter. The attitude indicator indicated 'gyro computer' for 5-10 seconds before those flags went away; and unfortunately; I drifted off of localizer and got to 3/4 deflection. As I was correcting; tower called to inform us we were off course. I told them we had an inverter failure; switched to our 2nd inverter; and were correcting. They asked if we wanted vectors; and I said; 'I'm on localizer now; is that what you're showing?' she confirmed I was on localizer. We then landed.it was a system failure which caused me to drift off localizer. In the future; I will ask for vectors and go around. As for the plane; in my opinion; the root cause has not been identified; because this is the fourth inverter #1 failure in about a month.
Original NASA ASRS Text
Title: SA227 Captain reported an inverter failure on final approach causing them to deviate from the localizer on the ILS.
Narrative: At the time of the event; the FO (First Officer) was the pilot flying; we were cleared for the ILS approach; were on localizer; and were descending to 2400. Right before the FAF (Final Approach Fix); we both heard a 'pop.' The FO's attitude indicator was flagged; as was the pilot's attitude indicator. At first; we thought circuit breakers had popped; so we looked and saw none popped. A second later; we saw L AC BUS and R AC BUS illuminated; so that meant Inverter #1 had failed. The Captain took control of the aircraft; and we switched to the #2 Inverter. The attitude indicator indicated 'GYRO COMPUTER' for 5-10 seconds before those flags went away; and unfortunately; I drifted off of localizer and got to 3/4 deflection. As I was correcting; Tower called to inform us we were off course. I told them we had an inverter failure; switched to our 2nd inverter; and were correcting. They asked if we wanted vectors; and I said; 'I'm on localizer now; is that what you're showing?' She confirmed I was on localizer. We then landed.It was a system failure which caused me to drift off localizer. In the future; I will ask for vectors and go around. As for the plane; in my opinion; the root cause has not been identified; because this is the fourth Inverter #1 failure in about a month.
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.