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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Air carrier large transport lost half of its electric power at high altitude cruise and diverted to an en route maintenance base.
| Attributes | |
| ACN | 270929 |
| Time | |
| Date | 199405 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : den |
| State Reference | CO |
| Altitude | msl bound lower : 37000 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv artcc : zma |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| 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 : commercial pilot : instrument |
| Experience | flight time last 90 days : 200 flight time total : 8000 flight time type : 3500 |
| ASRS Report | 270929 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
In cruise when right AC bus light illuminated along with right bus isolation light illuminated. Multiple EICAS warnings associated with unpwred right bus. Lower EICAS screen and first officer's FMC screen went blank. Attempted resetting generator switch and generator field with no results. Started APU: however, its generator would not pick up the right AC bus load. Essentially, we were down to 1 generator. Our procedures don't allow us to reset the bus isolation switch for a single bus failure. Since the AC bus was unpwred, the battery charger was inoperative: therefore, the right IRS was discharging the battery. Left unattended we would have lost the battery and greatly complicated our problems. We turned off right IRS and rerted to msp for repairs. Recommendation: suggest a little more latitude for crews to attempt other avenues of approach. We could have switched generator switch off, reset bus isolation switch. Then, the left bus or APU generator could have picked up the load. Add to checklist to turn off right IRS (if not needed) during a right AC bus failure.
Original NASA ASRS Text
Title: ACR LGT LOST HALF OF ITS ELECTRIC PWR AT HIGH ALT CRUISE AND DIVERTED TO AN ENRTE MAINT BASE.
Narrative: IN CRUISE WHEN R AC BUS LIGHT ILLUMINATED ALONG WITH R BUS ISOLATION LIGHT ILLUMINATED. MULTIPLE EICAS WARNINGS ASSOCIATED WITH UNPWRED R BUS. LOWER EICAS SCREEN AND FO'S FMC SCREEN WENT BLANK. ATTEMPTED RESETTING GENERATOR SWITCH AND GENERATOR FIELD WITH NO RESULTS. STARTED APU: HOWEVER, ITS GENERATOR WOULD NOT PICK UP THE R AC BUS LOAD. ESSENTIALLY, WE WERE DOWN TO 1 GENERATOR. OUR PROCS DON'T ALLOW US TO RESET THE BUS ISOLATION SWITCH FOR A SINGLE BUS FAILURE. SINCE THE AC BUS WAS UNPWRED, THE BATTERY CHARGER WAS INOP: THEREFORE, THE R IRS WAS DISCHARGING THE BATTERY. LEFT UNATTENDED WE WOULD HAVE LOST THE BATTERY AND GREATLY COMPLICATED OUR PROBS. WE TURNED OFF R IRS AND RERTED TO MSP FOR REPAIRS. RECOMMENDATION: SUGGEST A LITTLE MORE LATITUDE FOR CREWS TO ATTEMPT OTHER AVENUES OF APCH. WE COULD HAVE SWITCHED GENERATOR SWITCH OFF, RESET BUS ISOLATION SWITCH. THEN, THE L BUS OR APU GENERATOR COULD HAVE PICKED UP THE LOAD. ADD TO CHKLIST TO TURN OFF R IRS (IF NOT NEEDED) DURING A R AC BUS FAILURE.
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.