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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Inadvertent pulling of AC bus circuit breaker caused gyro, autoplt, and autothrottles to be inoperative. Before flight crew discovered the circuit breaker, the aircraft heading deviated as well as altitude. Circuit breaker was reset and all system returned to normal.
| Attributes | |
| ACN | 333430 |
| Time | |
| Date | 199604 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : zdv |
| State Reference | CO |
| Altitude | msl bound lower : 32620 msl bound upper : 33000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv tower : iad |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 195 flight time total : 14000 flight time type : 500 |
| ASRS Report | 333430 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
On flight from cle to las while en route at FL330 between oneil and cheyenne, the first officer was flying. I (captain) got out of my seat to retrieve something from my suitcase. While picking my suitcase up from behind my seat, I either bumped or a strap caught on an AC bus circuit breaker and pulled it. Since I was not looking at the instrument panel, I did not see the flags. I noticed the flags on the first officer instrument panel about the same time the first officer did. Since his flight instruments were inoperative, I told him I would fly the aircraft and he should get out our abnormal checklist. We discovered a circuit breaker was out and reset the circuit breaker. I advised center we had a problem with our directional gyro and we might need some help till we get our directional gyros back. Our heading turned approximately 120 degrees till we got everything back in order. Our autoplt and autothrottles were inoperative also, and we lost about 380 ft, but recovered immediately. Once we reset the circuit breaker and all power was restored, all system were normal. The problem started by bumping the circuit breaker. I think in retrospect I should have been more careful in moving my suitcase. Also, as captain, I should have documented the incident in aircraft log. I didn't, as the problem was pilot induced, and once the power was restored, the aircraft operated normally.
Original NASA ASRS Text
Title: INADVERTENT PULLING OF AC BUS CIRCUIT BREAKER CAUSED GYRO, AUTOPLT, AND AUTOTHROTTLES TO BE INOP. BEFORE FLC DISCOVERED THE CIRCUIT BREAKER, THE ACFT HDG DEVIATED AS WELL AS ALT. CIRCUIT BREAKER WAS RESET AND ALL SYS RETURNED TO NORMAL.
Narrative: ON FLT FROM CLE TO LAS WHILE ENRTE AT FL330 BTWN ONEIL AND CHEYENNE, THE FO WAS FLYING. I (CAPT) GOT OUT OF MY SEAT TO RETRIEVE SOMETHING FROM MY SUITCASE. WHILE PICKING MY SUITCASE UP FROM BEHIND MY SEAT, I EITHER BUMPED OR A STRAP CAUGHT ON AN AC BUS CIRCUIT BREAKER AND PULLED IT. SINCE I WAS NOT LOOKING AT THE INST PANEL, I DID NOT SEE THE FLAGS. I NOTICED THE FLAGS ON THE FO INST PANEL ABOUT THE SAME TIME THE FO DID. SINCE HIS FLT INSTS WERE INOP, I TOLD HIM I WOULD FLY THE ACFT AND HE SHOULD GET OUT OUR ABNORMAL CHKLIST. WE DISCOVERED A CIRCUIT BREAKER WAS OUT AND RESET THE CIRCUIT BREAKER. I ADVISED CTR WE HAD A PROB WITH OUR DIRECTIONAL GYRO AND WE MIGHT NEED SOME HELP TILL WE GET OUR DIRECTIONAL GYROS BACK. OUR HDG TURNED APPROX 120 DEGS TILL WE GOT EVERYTHING BACK IN ORDER. OUR AUTOPLT AND AUTOTHROTTLES WERE INOP ALSO, AND WE LOST ABOUT 380 FT, BUT RECOVERED IMMEDIATELY. ONCE WE RESET THE CIRCUIT BREAKER AND ALL PWR WAS RESTORED, ALL SYS WERE NORMAL. THE PROB STARTED BY BUMPING THE CIRCUIT BREAKER. I THINK IN RETROSPECT I SHOULD HAVE BEEN MORE CAREFUL IN MOVING MY SUITCASE. ALSO, AS CAPT, I SHOULD HAVE DOCUMENTED THE INCIDENT IN ACFT LOG. I DIDN'T, AS THE PROB WAS PLT INDUCED, AND ONCE THE PWR WAS RESTORED, THE ACFT OPERATED NORMALLY.
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.