 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
An air carrier B737 flight crew experiences an electrical fault on bus #1. They were able to restore power to bus #2 and used the auxiliary power unit as a backup source.
| Attributes | |
| ACN | 382767 |
| Time | |
| Date | 199710 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : orf |
| State Reference | VA |
| Altitude | msl bound lower : 35000 msl bound upper : 35000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc tower : mht |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 150 flight time total : 6800 flight time type : 1400 |
| ASRS Report | 382767 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance none taken : anomaly accepted other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
On a flight (B737-400) from isp to pbi, climbing through 34000 ft for 35000 ft, loss of both generator busses occurred. The captain became the PF and we referred to the aircraft checklist. The generator bus #2 was restored by deselecting generator bus #1. All electrical was restored, except what was on generator bus #1. After starting the APU, it was selected for generator bus #1. Loss of both generator busses occurred again. Deselecting the APU, generator bus #2 came back on line. After calling dispatch and discussing our options, we continued to proceed to pbi. The #2 generator was powering all electrical (except generator bus #1), without excess load or temperature. There was no need to divert since all standby power and battery indications were normal, plus the APU could supply the #2 generator bus (if necessary). The only change to our flight was the routing. Instead of flying overwater from diw to pbi, we rerouted along the coast. WX was VFR along the route to our destination. Forecast showers at our destination had moved to the south. The flight was completed without further incident. We surmised that xfer relays from generator bus #1 to xfer bus #1 were defective. Aircraft capabilities allowed generator bus #2 automatic connection to xfer bus #1, which it did within generator load limits. No navigation or other system degradation occurred in this confign. Only redundant items on the generator bus #1 were inoperative.
Original NASA ASRS Text
Title: AN ACR B737 FLC EXPERIENCES AN ELECTRICAL FAULT ON BUS #1. THEY WERE ABLE TO RESTORE PWR TO BUS #2 AND USED THE AUX PWR UNIT AS A BACKUP SOURCE.
Narrative: ON A FLT (B737-400) FROM ISP TO PBI, CLBING THROUGH 34000 FT FOR 35000 FT, LOSS OF BOTH GENERATOR BUSSES OCCURRED. THE CAPT BECAME THE PF AND WE REFERRED TO THE ACFT CHKLIST. THE GENERATOR BUS #2 WAS RESTORED BY DESELECTING GENERATOR BUS #1. ALL ELECTRICAL WAS RESTORED, EXCEPT WHAT WAS ON GENERATOR BUS #1. AFTER STARTING THE APU, IT WAS SELECTED FOR GENERATOR BUS #1. LOSS OF BOTH GENERATOR BUSSES OCCURRED AGAIN. DESELECTING THE APU, GENERATOR BUS #2 CAME BACK ON LINE. AFTER CALLING DISPATCH AND DISCUSSING OUR OPTIONS, WE CONTINUED TO PROCEED TO PBI. THE #2 GENERATOR WAS POWERING ALL ELECTRICAL (EXCEPT GENERATOR BUS #1), WITHOUT EXCESS LOAD OR TEMP. THERE WAS NO NEED TO DIVERT SINCE ALL STANDBY PWR AND BATTERY INDICATIONS WERE NORMAL, PLUS THE APU COULD SUPPLY THE #2 GENERATOR BUS (IF NECESSARY). THE ONLY CHANGE TO OUR FLT WAS THE ROUTING. INSTEAD OF FLYING OVERWATER FROM DIW TO PBI, WE REROUTED ALONG THE COAST. WX WAS VFR ALONG THE RTE TO OUR DEST. FORECAST SHOWERS AT OUR DEST HAD MOVED TO THE S. THE FLT WAS COMPLETED WITHOUT FURTHER INCIDENT. WE SURMISED THAT XFER RELAYS FROM GENERATOR BUS #1 TO XFER BUS #1 WERE DEFECTIVE. ACFT CAPABILITIES ALLOWED GENERATOR BUS #2 AUTO CONNECTION TO XFER BUS #1, WHICH IT DID WITHIN GENERATOR LOAD LIMITS. NO NAV OR OTHER SYS DEGRADATION OCCURRED IN THIS CONFIGN. ONLY REDUNDANT ITEMS ON THE GENERATOR BUS #1 WERE INOP.
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.