Narrative:

In sum: both the captain and first officer of an air carrier B737-300 reported this incident. Each reporter told essentially the same story. The aircraft departed into a low overcast, turning to the east towards high ground. About 10 mins into the flight, the #1 fuel valve light started flickering, then came on steady. Then all primary flight instruments went blank on the glass cockpit. There were no warning lights on the overhead panel and the pressurization stayed normal. The captain started the APU while the first officer checked that all circuit breakers were in place. The captain put APU power onto the left generator bus and passed control to the first officer. The captain had been flying using the standby instruments. The captain asked for an 'immediate return to sea,' describing the situation as a 'complete electrical failure.' the captain's instruments were inoperative, while the first officer's instruments and the standby instruments were operating. The yaw damper, mach trim and speed trim were inoperative. The DME and transponder were inoperative for a time, then became operative when switched to the right side. The first officer tried to use the autoplt until the altitude started to drift. The approach was completed hand flying the aircraft. The landing was made to the longest runway, into the wind and was uneventful. After the crew left the cockpit, maintenance found that the #1 air- conditioning bus circuit breaker had 'popped.' callback conversation with reporter acn 327403 revealed the following information: the reporter has not yet gotten the final reply from his air carrier, but he has heard that maintenance found a circuit breaker that failed. It broke the circuit, but did not show 'popped' in the cockpit. The reporter has not seen this instrument failure before, 'only in the simulator.' maintenance changed the fuel valve, circuit breaker, and position transmitter to solve the fuel light problem. The reporter believes that these problems were entirely coincidental and not linked in any way. Callback conversation with reporter acn 326806 revealed the following information: this reporter has nothing more to offer than his captain. He, too, believes, that this was a one time aberration. He did not get out of his seat to check the circuit breaker panels, but he did loosen his seat belt so that he could touch every one to see that it was not 'popped.'

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Original NASA ASRS Text

Title: AN ACR MLG LOST ALL OF ITS PRIMARY FLT INSTS.

Narrative: IN SUM: BOTH THE CAPT AND FO OF AN ACR B737-300 RPTED THIS INCIDENT. EACH RPTR TOLD ESSENTIALLY THE SAME STORY. THE ACFT DEPARTED INTO A LOW OVCST, TURNING TO THE E TOWARDS HIGH GND. ABOUT 10 MINS INTO THE FLT, THE #1 FUEL VALVE LIGHT STARTED FLICKERING, THEN CAME ON STEADY. THEN ALL PRIMARY FLT INSTS WENT BLANK ON THE GLASS COCKPIT. THERE WERE NO WARNING LIGHTS ON THE OVERHEAD PANEL AND THE PRESSURIZATION STAYED NORMAL. THE CAPT STARTED THE APU WHILE THE FO CHKED THAT ALL CIRCUIT BREAKERS WERE IN PLACE. THE CAPT PUT APU PWR ONTO THE L GENERATOR BUS AND PASSED CTL TO THE FO. THE CAPT HAD BEEN FLYING USING THE STANDBY INSTS. THE CAPT ASKED FOR AN 'IMMEDIATE RETURN TO SEA,' DESCRIBING THE SIT AS A 'COMPLETE ELECTRICAL FAILURE.' THE CAPT'S INSTS WERE INOP, WHILE THE FO'S INSTS AND THE STANDBY INSTS WERE OPERATING. THE YAW DAMPER, MACH TRIM AND SPD TRIM WERE INOP. THE DME AND XPONDER WERE INOP FOR A TIME, THEN BECAME OPERATIVE WHEN SWITCHED TO THE R SIDE. THE FO TRIED TO USE THE AUTOPLT UNTIL THE ALT STARTED TO DRIFT. THE APCH WAS COMPLETED HAND FLYING THE ACFT. THE LNDG WAS MADE TO THE LONGEST RWY, INTO THE WIND AND WAS UNEVENTFUL. AFTER THE CREW LEFT THE COCKPIT, MAINT FOUND THAT THE #1 AIR- CONDITIONING BUS CIRCUIT BREAKER HAD 'POPPED.' CALLBACK CONVERSATION WITH RPTR ACN 327403 REVEALED THE FOLLOWING INFO: THE RPTR HAS NOT YET GOTTEN THE FINAL REPLY FROM HIS ACR, BUT HE HAS HEARD THAT MAINT FOUND A CIRCUIT BREAKER THAT FAILED. IT BROKE THE CIRCUIT, BUT DID NOT SHOW 'POPPED' IN THE COCKPIT. THE RPTR HAS NOT SEEN THIS INST FAILURE BEFORE, 'ONLY IN THE SIMULATOR.' MAINT CHANGED THE FUEL VALVE, CIRCUIT BREAKER, AND POS XMITTER TO SOLVE THE FUEL LIGHT PROB. THE RPTR BELIEVES THAT THESE PROBS WERE ENTIRELY COINCIDENTAL AND NOT LINKED IN ANY WAY. CALLBACK CONVERSATION WITH RPTR ACN 326806 REVEALED THE FOLLOWING INFO: THIS RPTR HAS NOTHING MORE TO OFFER THAN HIS CAPT. HE, TOO, BELIEVES, THAT THIS WAS A ONE TIME ABERRATION. HE DID NOT GET OUT OF HIS SEAT TO CHK THE CIRCUIT BREAKER PANELS, BUT HE DID LOOSEN HIS SEAT BELT SO THAT HE COULD TOUCH EVERY ONE TO SEE THAT IT WAS NOT 'POPPED.'

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.